How To Repair Oil Furnaces

Troubleshooting Oil Furnaces and Oil Heaters

Cleaning or replacing filters is a job anyone can do, and often it's the reason an oil furnace isn't performing at peak levels. Use this chart to see if the problem with your furnace might be fixed with a filter change.

Problem Possible cause  Solution 
Furnace won't run

1. No power.

1. Check for blown fuses or tripped
    circuit breakers at main entrance
    panel or at separate entrance panel;
    restore circuit. 
  2. Switch off.
2. Turn on separate power switch on
    or near furnace. 
  3. Motor overload.
3. Wait 30 minutes; press reset button.
    Repeat if necessary. 
  4. No fuel.
4. Check tank; if necessary, refill tank. 
  5. Fuel line blockage.
5. Clean oil filter and oil pump strainer.
    If problem persists, call a
Burner won't fire  1. No fuel.  1. Check tank; if necessary, refill tank. 
  2. No ignition spark.

2. Press reset button on stack control;
    if necessary, clean stack control.
    If no result, call a professional.
    If furnace has electric-eye safety,
    clean safety; if no result, call a
Not enough heat
1. Thermostat set
    too low. 
1. Raise thermostat setting 5°.
  2. Air filter dirty.  2. Clean or replace air filter. 
  3. Blower clogged.  3. Clean blower assembly. 
  4. Registers closed
    or blocked.
4. Make sure all registers are open;
    make sure they are not blocked by
    rugs, drapes, or furniture. 
  5. System out of
5. Balance system. 
  6. Blower belt loose
    or broken. 
6. Adjust or replace belt.
  7. Burner dirty.  7. Call a professional. 
Furnace turns
on and off
1. Air filter dirty.
2. Oil filter dirty.
3. Motor and/or blower
1. Clean or replace air filter.
2. Clean or replace oil filter.
3. If motor and blower have oil
      needs lubrication.
    ports, lubricate.
  4. Blower clogged.
4. Clean blower assembly.
  5. Stack control faulty. 5. Call a professional.
Blower won't
1. Blower control
1. Reset thermostat from ON
stop running      set wrong.      to AUTO.
  2. Limit switch set
2. Reset limit switch. 
Furnace noisy
1. Access panels loose.
1. Mount and fasten access
    panels correctly. 
  2. Belts sticking, worn,
    or damaged.
2. Spray squeaking belts with fan
    belt dressing; replace worn
    or damaged belts.
  3. Blower belt too
    loose or too tight. 
3. Adjust belt.

  4. Motor and/or blower
    needs lubrication. 
4. If motor and blower have oil
    ports, lubricate. 
  5. Burner dirty.  5. Call a professional. 

Oil filters should be changed twice a year. Find out when and how to do it on the next page.

For more articles on home repair, check out the following links.
  • Furnace Maintenance: Save yourself time and money by learning the steps to keep youor furnace in prime condition.
  • Major Appliance Repair: If the furnace isn't the only thing in your house on the fritz, you can learn how to fix other machines in this article.
  • Small Appliance Repair: Once you've tackled the furnace, a toaster or blender seems like child's play. Find out how to fix them here.
  • Thermostat Maintenance: To make sure there's actually a problem with your heating system, you may want to check the thermostat, too. Learn how to calibrate a thermostat.