Appliances are built to perform. They work hard, year after year, usually without too many problems. They're easy to take for granted. The result is that when an appliance breaks down, you may be completely at a loss -- you don't know how it works, you have no idea why it stopped working, and you certainly don't know how to fix it.
What can you do? You can pay a professional to fix it, or you can fix it yourself and save money. This article will provide you with all the information you need to know to pull your major appliances apart and then put them back together in working order. But before you attack the refrigerator with a screwdriver, let's get some background information on major appliances.
Most appliances operate on your home's electrical system: They use AC current from the circuit wiring in your home. Small appliances work on 110-120-volt circuits, and the plugs on their cords have two blades. Large or major appliances, such as air conditioners, dryers, and ranges, usually require 220-240-volt wiring and cannot be operated on 110-120-volt circuits. Large appliances are wired with a grounding wire; their plugs have two blades and a prong. This type of appliance must be plugged into a grounded outlet -- one with openings to accept both blades and grounding prong -- or grounded with a special adapter plug. All appliances are labeled -- either on a metal plate or on the appliance casing -- with their power requirements in watts and volts, and sometimes in amps.
Small appliances are usually fairly simple machines. They may consist of a simple heating element, a fan, a set of blades, or rotating beaters attached to a drive shaft; or they may have two or three simple mechanical linkages. Repairs to these appliances are usually correspondingly simple. Large appliances are more complex -- one major appliance, such as a washing machine, may have a motor, a timer, and a pump, as well as various valves, switches, and solenoids. With this type of appliance, problems can occur in either the control devices or the mechanical/power components. Failure of a control device may affect one operation or the entire appliance; failure of a mechanical/power device usually affects only the functions that depend on that device. When a major appliance breaks down, knowing how to diagnose the problem is as important as knowing how to fix it.
Because major appliances are so complex, it usually isn't obvious where a malfunction is. (Many newer appliances include electronic diagnostics that can be interpreted from the owner's manual.) The first step is to decide whether the problem is in a control device or a mechanical device. In a dryer, for example, the control devices govern the heat, and the mechanical components turn the drum. Which system is affected? If the drum turns, but the dryer doesn't heat, the problem is in the control system. If the dryer heats, but the drum doesn't turn, the problem is mechanical. This kind of analysis can be used to pinpoint the type of failure -- control system or mechanical system -- in all large appliances.
To find out exactly what the problem is, you must check each part of the affected system to find the malfunctioning part. This isn't as difficult as it sounds, because appliance components work together in a logical sequence. Starting with the simplest possibilities, you can test the components one by one to isolate the cause of the failure.
Repairing Major Appliances
There are three very important rules you must follow when you attempt to make any type of appliance repair. Don't ever try to save time or money by ignoring these rules. You won't save anything at all, and you could end up hurting yourself or ruining the appliance.
- Always make sure the electric power and/or the gas supply to the appliance is disconnected before you test the appliance to diagnose the problem or make any repairs. If you turn the power on to check your work after making a repair, do not touch the appliance; just turn the power on and observe. If adjustments are needed, turn the power off before you make them.
- If the parts of an appliance are held together with screws, bolts, plugs, and other take-apart fasteners, you can probably make any necessary repairs. If the parts are held together with rivets or welds, don't try to repair the appliance yourself. Call a professional service person.
- In most cases, broken or malfunctioning appliance parts can be replaced more quickly and inexpensively than they can be repaired by you or a professional. Replace any broken or malfunctioning parts with new parts made especially for that appliance. If you cannot find an exact replacement for the broken part, it's okay to substitute a similar part as long as it fits into the old space. In this case, refer to the manufacturer's instructions for installation.
Appliance parts are available from appliance service centers, appliance-repair dealers, and appliance-parts stores. You don't always have to go to a specific brand-name appliance parts center to obtain the parts and service you need for brand-name appliances, so you do have some shopping/service choices. If you can't locate a parts service center in your area, order the part you need directly from the manufacturer. The name and address of the appliance manufacturer are usually printed on the appliance. Be sure to give the manufacturer all the model and parts data possible for the appliance. If available, search on the Internet for replacement parts.Before you make any appliance repair, make sure the appliance is receiving power. Lack of power is the most common cause of appliance failure. Before you start the testing and diagnosis process, take these preliminary steps:
- Check to make sure that the appliance is properly and firmly plugged in and that the cord, the plug, and the outlet are working properly. To determine whether an outlet is working, test it with a voltage tester.
- Check to make sure the fuses and/or circuit breakers that control the circuit have not blown or tripped. There may be more than one electrical entrance panel for your home, especially for 220-240-volt appliances such as ranges and air conditioners. Check for blown fuses or tripped circuit breakers at both the main panel and the separate panel.
- Check to make sure fuses and/or breakers in the appliance itself are not blown or tripped. Push the reset buttons to restore power to appliances such as washers, dryers, and ranges. Some ranges have separate plug-type fuses for oven operation; make sure these fuses have not blown.
- If the appliance uses gas or water, check to make sure it is receiving an adequate supply.
- Check the owner's manual for the appliance. Many manufacturers include helpful problem/solution troubleshooting charts. If you don't have a manual for an appliance, you can probably get one -- even for an old or obsolete appliance -- from the manufacturer's customer service department.
All right, now that we have the preliminaries out of the way, it's time to dive right in. Move on to the next section to learn how to disassemble a major appliance and the details on grounding systems.
How to Disassemble Major Appliances
Before you can repair a major appliance, you'll have to disassemble all or part of it. All major appliances are different, but the disassembly procedure is about the same: Remove the parts in reverse of the way the manufacturer put them together. Check your owner's manual for assembly diagrams and instructions. Remember that you'll have to put the appliance back together again, so lay the parts out in the order in which you remove them, with fasteners in hand. If you aren't sure you'll be able to put the appliance back together, take notes and make drawings as you work. Label all terminals and wires if you must disconnect more than one wire at a time.
To disassemble a major appliance, start with the obvious knobs and fasteners. Many knobs and dials are push-fit. Simply pull them off their control shafts. Knobs may also be held in place by setscrews, springs or spring clips, or pins; or they may be screwed on. All of these types of fasteners are easy to release. Housing panels are usually held by screws or bolts. They may also be held in place by tabs. Sometimes, parts are force-fitted and may be hard to remove. Never force parts apart; look for hidden fasteners. For instance, there may be no obvious fasteners holding the top of a washer in place. However, you can locate the clips that hold the top of the washer down by sticking the blade of a putty knife into the seam where the top panel meets the side panel. Run the knife along the seam until you hit an obstruction; this is a spring clip. To release the clip, push the blade of the knife directly into the clip, at a right angle to the seam, while pushing up on the top panel. Repeat this procedure to locate and remove any other spring clips holding the top panel in place. Then lift the panel off.
Fasteners may also be hidden under a nameplate or company logo, behind a scarcely visible plastic plug, under a cork pad on the bottom of the appliance, or under an attachment plate. Carefully pry up the part that is hiding the fastener. When you reassemble the appliance, snap the concealing part back over the fastener, or, if necessary, glue it into place. If you can't find hidden fasteners on force-fitted parts, warm the parts gently with a heating pad; the heat may make disassembly easier. Inside the appliance, watch for clips holding parts to the housing panel.
Before reassembling a major appliance, carefully vacuum inside the appliance to remove all dust and lint. Check for other problems and make any necessary repairs or adjustments. If the appliance has a motor, lubricate the motor. Check carbon brushes in universal motors for wear and replace them if necessary. Lubricate moving parts sparingly and make sure electrical contacts are clean.
Reassemble the appliance in reverse of the way you took it apart. Never force parts together or overtighten fasteners. Make sure moving parts, such as armatures or gears, don't bind. After reassembly, connect the power and turn it on. If it makes noise, smells, or overheats, turn it off and disconnect the power. Then go back over your repair.
Many homes today are equipped with electrical outlets that have a three-wire system. The third wire is a grounding device and operates the same way as the grounding wire on stationary appliances. Large appliances, whose plugs have two blades and a prong, should be plugged into a grounded outlet or grounded with a special adapter plug. Caution: Never remove the prong from a three-wire plug to make it fit an ungrounded outlet; always use an adapter plug.
Proper grounding is vital for metal-framed appliances. If the insulation on the power cord of a metal-framed appliance (such as a washer or dryer) is broken or worn away at the point where the cord enters the frame, contact between the current conductor and the metal frame could charge the whole appliance with electricity. When this happens, dampness can cause a shock hazard even if the appliance is properly grounded. If you accidently touch a charged metal frame in a damp location or while touching a water faucet or radiator, the current would surge through you and could kill you.
There are three things you can do to eliminate this hazard. First, make sure your major appliances are properly grounded. Second, make sure that all appliance cords are in good repair, and that they are not chafing against burrs or rough spots where they enter the appliance frame. Third, add a ground-fault circuit interrupter (GFI or GFCI) to the circuit. GFIs are monitoring devices that instantly shut off a circuit when a current leak occurs. They are required by the National Electrical Code on all new 15-amp and 20-amp outdoor outlets and for wiring in bathrooms, where dampness is a common problem. GFIs are available to plug into existing outlets as adapters, to replace outlets, and to replace circuit breakers in the electrical entrance panel. A professional electrician should install the circuit-breaker type; you can install the other types yourself. Ground-fault circuit interrupters are available at electrical supply and home center stores.
In double-insulated appliances and power tools, the electrical components are isolated from any parts of the appliance that could carry electrical current. However, these appliances are not completely shock-safe. You should use caution with any electrical device. For example, never operate an electric drill while standing on a wet surface--and never drill into a wall where power lines may be present. Double-insulated appliances and tools should almost always be repaired by a professional, because the double insulation depends on a plastic housing and a plastic buffer between parts that carry electricity. If these plastic parts are not properly positioned, the appliance or tool could produce a harmful electrical shock. Appliances and tools that are double insulated are usually labeled as such.
As you've seen, proper safety around electricity is essential. In the next section, we will discuss how to repair power cords and plugs.
Repairing Power Cords and Plugs
Major appliances have many components in common, making repairs easier. For example, once you've learned to repair a power cord on a refrigerator, you can apply the same skills to repairing a washing machine's power cord.
The following sections explain common devices that are used on major appliances and offers tips on how to repair them.
Power Cords and Plugs
Many appliance "breakdowns" are really due to worn, frayed power cords or plugs that no longer make proper electrical contact. To ensure safe operation, you should check all appliance cords for problems periodically and replace frayed or broken cords immediately. When you suspect a cord is faulty, remove it from the appliance and test it with a continuity tester. Clip the tester to one blade of the plug and touch the probe to one of the two wires -- or, if it's a plug-in cord, insert the probe into one of the two holes -- at the appliance end of the cord. If the tester lights or buzzes, move it to the other wire or hole and test again. Repeat this procedure to test the other blade of the plug. If the tester lights or buzzes at every test point, the cord is not faulty; if it fails to light or buzz at any point, the cord or the plug is faulty. You can pinpoint the defect by cutting off the plug and testing the cut end of the cord; if the tester lights or buzzes at all test points now, the plug is the defective part. The damaged component -- cord, plug, or both -- should be replaced.
Often, the hardest part of replacing an appliance cord is determining how the appliance comes apart so that you can remove the old cord and attach a new one. Sometimes all you have to do is remove the cover from a connection box. In other cases, as with a small hair dryer, the unit itself must be partially disassembled before you can reach the terminals. In nearly all cases, the cord is held in place by a clamp or by a fitted strain-relief device. To remove the cord, unscrew the terminal screws or pull the pressure connectors apart, loosen the clamp or remove the strain-relief device, and pull the cord out. Installation of the new cord is simply a reverse procedure. Be sure to save the strain-relief device and replace it on the new cord. If you damage the strain-relief device when you remove it, replace it with a new one of the same type.
In some equipment, the conductor ends are looped around terminal screws, making new connections easy. Carefully strip off the outer insulation (not the insulation on the inner wires) for about 2 inches at the end of the cord. Then, using a wire stripper, remove about 1/2 inch of insulation from the end of each conductor wire. Twist the exposed filaments of each wire clockwise into a solid prong. Loosen the terminal screws and loop each bare wire end clockwise around a screw. Tighten the screws firmly. Connect the wires at the appliance end of the new cord the same way the old wires were connected.
If only the plug on a major appliance is faulty, you can attach a new plug to the old cord. Male plugs, with two blades or with two blades and a grounding prong, plug into an outlet. Female plugs, often used at the appliance end of the cord, have terminal holes instead of blades. Male plugs can usually be taken apart so you can access the terminal screws. Female plugs may be held together by rivets or by screws. Screw-held plugs can be taken apart, but rivet-held plugs cannot be repaired.
When a plug malfunctions, open the plug, if possible, and check to make sure the conductor wires are properly attached to the plug's screw terminals. If the wires are loose, tighten the terminal screw. This may solve the problem; otherwise, the plug should be replaced. To attach a new male plug:
Step 1: Insert the cord end through the plug opening and pull it through for about five or six inches.
Step 2: Carefully strip off the outer insulation for about 2 inches. Then, using a wire stripper, remove about 1/2 inch of insulation from the end of each conductor wire.
Step 3: Twist the exposed filaments of each wire clockwise into a solid prong. After twisting the conductor ends, tie a tight knot with the inner wires of the cord. Then pull the plug down over the knot, leaving the exposed ends of the conductor wires sticking out. Loosen the terminal screws in the plug.
Step 4: On a two-wire plug, loop each wire around one prong and toward a screw terminal. Loop the bare wire end clockwise around the screw terminal and tighten the screw. If the screws are different colors, connect the white wire to the white screw and the black wire to the yellow screw. On a three-wire plug, use the same technique to connect each of the three wires to a terminal screw. Connect the green grounding wire to the green screw terminal.
Step 5: When the conductor wires are firmly secured to the terminal screws, slide the cardboard insulator over the blades of the plug. If the plug has a clamp-type sleeve, clamp it firmly around the cord.
In the next section, we will delve deeper into your appliances, and learn how to repair gaskets, wiring, switches, and thermostats.
Repairing Gaskets, Wiring, Switches, and Thermostats
We will continue our tour through the inner-workings of your major appliances with an examination of three of the most common components. Let's get started with an item you'll find in most machines that use water -- gaskets.
Gaskets do two things: They prevent leaks of water and air, and they increase the efficiency of the appliance. When a gasket fails, it should be replaced as soon as possible. To determine whether a gasket is faulty, inspect it for cracks and tears. It should feel spongy. If the gasket has hardened, it should be replaced. Be sure to replace a faulty gasket with a new one made specifically for the appliance. Do not use a universal, fit-all gasket.
There are two common types of gaskets -- flush-mounted and channel-mounted. A flush-mounted gasket is secured to the door by a series of screws or clips, or held in place by a retaining strip or a panel. A channel-mounted gasket is held in a retaining groove. A splining or gasket tool makes installation easier. Use gasket cement to install either type of gasket if specified by the manufacturer. To replace a gasket:
Step 1: Remove the old gasket. If it's channel-mounted, pull it carefully out of the channel. If it's flush-mounted, remove the fasteners, retaining strip, or panel to release the gasket.
Step 2: Clean the gasket area thoroughly with warm water and liquid detergent, or with mineral spirits, if necessary. Dry the door.
Step 3: Install the new gasket, smoothing it evenly into place and easing it around corners. Use gasket cement if specified by the manufacturer. If you're installing a channel-mounted gasket, press it into place with a splining tool. Make sure the gasket is properly and smoothly positioned, with no part sticking up or curled under.
Step 4: Replace the fasteners or the retaining strip or the panel and its fasteners. Remove any excess gasket cement with mineral spirits, but be very careful not to damage the appliance's finish.
Many appliance repair tasks involve wiring or connecting wires to install a new electrical component. The electrical wires in appliances may be connected in one of several ways, including the basic screw-terminal connection, the push-in terminal, and sometimes the sleeve-type lug terminal. Wires may also be joined with the solderless connectors called wirenuts. Components that have many wires -- washer timers, for instance, which control several operating cycles -- are often connected in a wiring harness: a group of wires enclosed in a plastic sleeve. Each type of wire connection, for each individual wire and each wire of a harness, must be properly made when you install a new component. Before you disconnect any wiring in an appliance, make sure you know how it's attached. When you install the new component, attach its wires the same way.
Switches operate by making contact with the conductor of an electrical circuit. When an appliance is plugged in, it's connected to a circuit in your home. Power runs through the wires of the circuit to the appliance. When the appliance's on/off switch is turned on, the conductors of the appliance cord are moved into contact with the circuit conductors, and electricity flows through the switch to operate the appliance. The current flows in a loop through the appliance, making a complete circuit back through the switch to the line wires. Other basic appliance components are variations of switches. Rheostats, thermostats, solenoids, and timers, for example, are all switches or secondary switches. These components operate inside appliances to turn on motors, open and close valves, control heating elements, and turn on different parts of the appliance during different cycles, such as the rinse and spin cycles of a washer. There are several common types of switches -- push buttons, toggles, rockers, slides, throw switches, and so on.
All switches consist of electrical contacts in a mechanical housing. Switch failure can be caused by problems with either the contacts or the housing. When a switch malfunctions, turn it to the ON position and watch to see if the contacts are moved into position so that they touch. If the contacts are not operating properly, the switch housing is faulty, and the switch should be replaced. If the switch's mechanical operation is all right, its contacts may be dirty or misaligned. If the switch has terminal screws, they may be loose. If the contacts are dirty or corroded, rub them gently with a fine emery board and then with a soft cloth. If they're misaligned, bend them gently back into place. Tighten any loose terminal screws. If the contacts or screws are badly corroded, the switch should be replaced. To determine whether a switch is working properly:
Step 1: Disassemble the appliance to test the switch with a continuity tester or a VOM set to the RX1 scale. For a full explanation of continuity testers and VOMs, click here.
Step 2: With the appliance unplugged, hook the clip of the continuity tester to one lead of the switch and touch the probe to the other; or touch one probe of the VOM to each terminal.
Step 3: Turn on the switch. If the switch is functioning, the continuity tester will light or buzz, and it will stop glowing or buzzing when the switch is turned off; or the VOM will read zero. If the tester doesn't light or buzz, or the VOM reads higher than zero, the switch is faulty and should be replaced. (Note that some switches should have a higher reading than zero, as detailed for each appliance.)
Step 4: Replace a defective switch with a new one of the same type, and connect it in exactly the same way the old switch was connected.
A thermostat is a switch that controls temperature in a heating element or a cooling device. Thermostats used in appliances may use a bimetal strip, bimetal thermodiscs, or a gas-filled bellows chamber to control the electrical contact. Faulty bimetal-strip and thermodisc thermostats should be replaced. Gas-filled thermostats can sometimes be professionally repaired. If repair is possible, it is much less expensive than replacement. To determine whether a thermostat is functioning:
Step 1: Disassemble the appliance to access the thermostat, and test it with a continuity tester or a VOM set to the RX1 scale.
Step 2: With the appliance unplugged, hook the clip of the continuity tester to one lead of the thermostat and touch the probe to the other; or touch one probe of the VOM to each terminal. The continuity tester should light or buzz; or the VOM should read zero.
Step 3: Turn down the temperature control dial; you'll see the contact points open at the thermostat. The tester should stop glowing or buzzing when the contacts open.
Step 4: If the thermostat is faulty, replace it with a new one. Follow the manufacturer's instructions.
As we mentioned in the introduction, most major appliances have two types of parts -- mechanical and control. Up to now we have covered only mechanical parts. In the next section, we will start to learn how to repair control devices.
Repairing Heating Elements and Timers
Many appliances perform several functions -- for example, the various cycles of a washer or dishwasher. These appliances operate automatically; once the on/off switch is turned on, switch components inside the appliance take over to control heat, water or fuel flow, motor speed, and other variables. The most important of these devices -- used to operate switches, levers, and valves automatically -- are solenoids (a current-carrying coil), relays, and sensor/responder pairs.
Heating elements work very simply. Unlike conductors, they are made of metal with high electrical resistance. When current flows through the element, this high resistance prevents it from flowing easily. Current must work to get through the element, and this work is converted into heat. When the current is turned off, the element cools. There are three types of heating elements: wire, ribbon, and rigid. To determine whether a heating element is functioning:
Step 1: Disassemble the appliance to access the element and test it with a continuity tester or a VOM set to the RX1 scale.
Step 2: With the appliance unplugged, hook the clip of the continuity tester to one terminal of the heating element and touch the probe to the other terminal; or touch one probe of the VOM to each terminal. If the element is functioning, the tester will light or buzz; or the VOM will read from 15 to 30 ohms. If the tester doesn't light or buzz, or the VOM reads higher than 30 ohms, the element is faulty. Replace it.
Note: If you use a continuity tester, look closely at the tester, especially if it is the light-up type. Some heating elements have an extremely high resistance factor, and the light may produce only a dim glow or a faint buzz. This reaction does not mean that the element is faulty, but rather that it converts current to heat efficiently.
The operation of a major appliance that has several cycles (for example, a washer, dishwasher, dryer, frost-free refrigerator, or range) is controlled by a timer -- a complex rotary switch powered by a small synchronous motor. The timer consists of a shaft, gears, and a series of notched cams, one for each circuit or cycle. The timer itself is powered by the timer motor; the appliance is powered by the much larger appliance motor. When the switch is turned on, electrical contact is made with the timer motor, and a spring on a trip arm is coiled. The arm trips when the spring is tight, releasing the spring and moving the cam of the switch to the next circuit. At the last cycle, contact with the motor is broken, and the timer turns the appliance off.
When a timer malfunctions, it should usually be replaced. Professional rebuilding is sometimes possible, but this is likely to be more expensive than replacement. Many timers are sealed units. Some timers have an adjustment shaft, which can be turned with a screwdriver blade. To determine whether a timer is functioning:
Step 1: Test the timer with a continuity tester or a VOM set to the RX1 scale. Make a sketch of the timer wires and then, with the appliance unplugged, disconnect all timer wires from their terminals. Make sure you'll be able to reconnect the wires exactly the same way.
Step 2: Touch or clip one probe of the tester or the VOM to the common terminal. Touch the other probe to each cycle terminal in turn. Rotate the timer control knob as you work. The continuity tester should light or buzz at each circuit; the VOM should read zero.
Step 3: If one or more circuits do not give these results, the timer is faulty and should be replaced. To replace a timer, disconnect its wires one at a time, connecting the corresponding wires of the new timer as you progress in order to avoid the chance of a misconnection.
Digital timers typically cannot be repaired and must be replaced.
Repairing a heating element didn't seem that dangerous, right? Well, heating elements lack a key ingredient that makes the repairs in our next section so dangerous -- combustible gas. Move on to the next page to learn how to repair a pilot light or thermocouple.
Repairing Pilot Lights and Thermocouples
Older gas appliances may have pilot lights that provide instant ignition when the gas is turned on. The pilot light is a small open flame that is fed by a steady flow of gas.
Problems occur when the gas flow is obstructed or misdirected, or when the pilot is blown out. In newer appliances, ignition may be achieved by a sparking device or a glow bar instead of a pilot light. In furnaces and water heaters, and in some ranges and dryers, the pilot light is accompanied by a safety device called a thermocouple -- a heat sensor that turns the gas off if the pilot flame is extinguished. Newer gas appliances have igniters that start the pilot light as needed.
Caution: Some older appliances may not have a safety device to turn the gas off when the pilot is extinguished. With any gas-fired appliance, if a strong smell of gas is present, do not try to relight the pilot or turn the appliance on, or turn any lights on or off. Get out of the house, leaving the door open, and call the gas company or the fire department immediately to report a leak.
A correctly adjusted pilot flame is steady and blue, and stands between 1/4 and 1/2 inch high. If the flame goes out repeatedly, it may be getting too little air; if it's yellow at the tip, it's getting too much air. To correct either condition, turn the pilot adjustment screw slightly, as directed by the manufacturer. When a pilot goes out, relighting it is simple:
Step 1: If there is a gas valve at the pilot, turn the valve to the OFF position and wait at least three minutes to let any built-up gas dissipate. After three minutes, turn the valve to the PILOT position. If there is a safety or reset button, push the button, and keep it depressed.
Step 2: Hold a lighted match to the pilot orifice and turn the gas valve to the ON position. Then, when the pilot is burning brightly, release the reset button. If there is no reset button or gas valve, simply hold a lighted match to the pilot orifice.
Step 3: If the pilot flame won't stay lit after several tries, it should be adjusted by a professional. Don't try to adjust the mechanism or tamper with the gas line.
If the appliance has a thermocouple, the problem may be a faulty thermocouple. The thermocouple, which operates as a safety device, turns the gas supply off when the pilot light goes out. It consists of a heat sensor connected to a solenoid; when the sensor is not heated by the pilot flame, the solenoid closes the gas supply line. When a thermocouple fails, the pilot light won't stay lighted. A burned out or broken thermocouple should be replaced. To replace a thermocouple:
Step 1: Unscrew the copper lead and the connection nut inside the threaded connection to the gas line.
Step 2: Under the mounting bracket at the thermocouple tube, unscrew the bracket nut that holds the tube in place.
Step 3: Insert a new thermocouple into the hole in the bracket, steel tube facing up and copper lead down.
Step 4: Under the bracket, screw the bracket nut over the tube. Push the connection nut to the threaded connection where the copper lead connects to the gas line. Make sure the connection is clean and dry.
Step 5: Screw the nut tightly into place, but do not overtighten it. Both the bracket nut and the connection nut should be only a little tighter than if hand-tightened.
In our final section, we will conclude our discussion of repairing major appliances with a detailed examination of -- of course -- motors. Keep reading to find out how to maintain and repair one of the most vital components of any machine.
Major appliance motors are usually dependable and long-wearing. You can prolong their life and increase their efficiency by keeping them clean and well lubricated. Use motor-driven appliances sensibly. Don't overload them, don't abuse them, and don't ignore problems until they become serious.
There are several basic rules for operating motor-driven appliances:
- Always connect an appliance to an adequate power source; a 220-240-volt appliance must be connected to a 220-240-volt outlet. If the outlet for a major appliance is not grounded, use a grounded adapter plug to ground the appliance.
- Never use a small appliance that's wet, and never operate any appliance while your hands are wet. If a large appliance, such as a washer or dryer, gets wet, do not operate it or try to unplug it. Have the motor examined by a professional before you use the appliance again.
- Never overload an appliance. Overloading causes inefficient operation and motor overheating, and can cause excessive wear. If a motor turns off because it's overloaded, reduce the load before restarting the appliance.
Universal MotorsUniversal motors consist of a rotor called an armature, with coils of wire wound around it, and a rotating cylinder called a commutator, with alternating strips of conducting and nonconducting material. The armature and the commutator are both mounted on the motor shaft. On each side of the commutator, a carbon brush carries current from the circuit. When the carbon brushes press against the commutator, the armature is magnetized and rotates. Most universal motors also have a cooling fan at the end of the shaft. Universal motors are used in many small and medium-size appliances. They provide strong power at both low and high speeds. Universal motors can operate on either AC or DC current. Their speed is controlled by a rheostat, a tapped-field control, a rectifier, or a governor, or by physical movement of the carbon brushes away from the armature.
Most universal motors are permanently lubricated and sealed by the manufacturer and require no further attention. Some universal motors, however, have covered lubrication ports, usually marked "oil," at the ends of the motor shaft. This type of motor should be oiled every six months, or according to the manufacturer's instructions. Lift each port's lid and apply a drop or two of No. 30 nondetergent motor oil (not all-purpose oil). Do not over-lubricate.
Many universal motor malfunctions are caused by wearing down of the carbon brushes, the soft blocks of carbon that complete the electrical contact to the motor's commutator. When these brushes become worn, the motor will spark, and electrical contact may be incomplete. You can solve both problems by replacing the brushes.
Brushes can be checked visually or tested with a continuity tester. Here's how:
Step 1: To sight-check the carbon brushes, remove the screws that hold the brushes and brush springs into the brush holders at the sides of the commutator. The screws will pop out of the screw holes; turn the motor over to tap out the brushes. The ends of the brushes should be curved to fit the commutator; if they're worn down, new brushes are needed.
Step 2: To check carbon brushes with a continuity tester, remove the motor lead wires from the circuit. Tag the wires as you disconnect them so that you'll be able to reconnect them properly. Hook the tester clip to one motor lead and touch the probe to the other lead; the tester should light or buzz. Slowly rotate the motor shaft, keeping the tester in position. If the tester doesn't light or buzz, or if it flickers or stutters when you turn the motor shaft, the brushes should be replaced. If the springs behind the brushes are damaged, they should be replaced as well.
Step 3: Replace worn carbon brushes and damaged springs with new ones made specifically for the motor. The model information (number and make) is stamped on a metal plate fastened to the motor, or embossed on the metal housing of the motor. If you can't find the model information, take the worn brushes and springs with you to an appliance-parts store to make sure you get the right kind. Insert the new springs and brushes in the brush holders, replace the brush assemblies, and secure the new brushes with the mounting screws that held the old brushes.
Don't attempt other repairs to a universal motor. If a serious malfunction occurs, buy a new motor or take the faulty motor to a professional for repairs. Most large universal motors are fastened to plate-type mountings. To remove the motor, disconnect the wires and remove the holding bolts and any belts that are present. If the faulty motor is in a small appliance, take the entire appliance to the repair shop. It may sometimes be less expensive to buy a new appliance than to have the old one repaired.
Split-phase motors consist of a rotor turning inside a stator (the non-moving portion of a motor) that has two wire coils: a starting winding and a running winding. Current flows through both windings when the motor is starting up, but when the rotor has reached about 75 to 80 percent of its top speed, the starting winding is turned off and only the running winding receives current. Split-phase motors operate on AC current. They are fairly powerful, and are used in appliances such as washing machines, dryers, and dishwashers.
These motors require no maintenance except cleaning and lubrication. Split-phase motors have a special auxiliary winding -- the starting winding. Don't try to make any repairs yourself. When a motor malfunctions, buy a new motor or take the faulty motor to a professional service person, whichever is less expensive. You can save the expense of a service call by removing the old motor from its mounting and installing the repaired or new motor yourself.
A capacitor-start motor is a shaded-pole motor with a capacitor (an energy-storing device) wired into the starting winding. The capacitor stores current and releases it in bursts to provide extra starting power. When the motor reaches about 75 percent of its top speed, the starting winding is turned off. Capacitor-start motors operate on AC current. They are very powerful and are used in appliances that require a high starting torque or turning power, such as air conditioners and furnaces.
Capacitor-start motors require regular cleaning to keep them free of lint and oil. Ventilation to the motor must be adequate. If the motor has oil ports, lift each port's lid and apply a drop or two of No. 30 nondetergent motor oil (not all-purpose oil). Do not over-lubricate.
Capacitor-start motors are usually hard to get at and have a capacitor and special auxiliary windings. Don't try to make any repairs yourself. When a motor malfunctions, call a professional service person.
Caution: Capacitors store electricity, even after the power to the appliance is turned off. When working with a capacitor-start motor, you must discharge the capacitor with a 20,000-ohm, 2-watt wire-wound resistor, as detailed for each appliance.
As with most do-it-yourself projects, repairing your own household appliances can save you both time and money. If you can remember to take it slow and label your steps, you can disassemble and reassemble most of the simple machinery in your home.
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