Air conditioning and heat pump

problems and solutions

Please read the whole page before proceeding.

  I have written about many service problems but I have not yet written a list of airconditioning problems and what causes them and what to do about them until now.

    There are many myths and wives tales about equipment I hope to dispel. Some of the problems can be solved by the home owner some need to be corrected by a skilled service technician with the proper tools.

    Some of the problems are minor and may cause increased energy consumption and others will cause destruction to your equipment if not corrected. Scott Meenen N3SJH

Definitions: I like to use the words indoor and outdoor a lot because heat pumps can cause some real problems with nomenclature of the components being that they reverse for heating and cooling, the words Fan and blower can cause confusion too. So to avoid this I try to use the words whenever I can.
Problem: Outdoor unit will not run:
Image of single pole and 1-12 pole contactors, 2 pole cotactors will break both sides of the line.Using clamp on ammeter to check current draw of unit.

 No power: Check for power at the disconnect and contactor on most residential units you should have 240 volts ac between the terminals and 120 volts to "ground" or "earth". Some disconnects have fuses in them. If you have circuit breakers I see little reason for fuses other than to create a service call. I usually replace them with copper tubing.

Most contactors will allow you to push them in manually (DANGER HIGH VOLTAGE). If the fan runs and the compressor does not then you have an electrical problem with the other component. There are cases where a grounded compressor or bad fan motor will cause the fan motor to run slow even though the contactor is not pulled in. A bad run capacitor will cause the compressor not to run and the same for the fan motor. Some units have a dual run capacitor that takes care of both and if it fails (it has an internal fuse) the motors will just hum (drawing high current) but not run. The compressor will have an internal overload that will disconnect the compressor after a few seconds of not starting. It will remake as soon as it cools, this condition can be mistaken as a bad compressor. Some compressor will require a "hard start kit" to solve starting problems and if it doesn't have one I recommend one as a preventative measure.

    Use a clamp on ammeter shown above to verify which parts are drawing current. If there is no current flow through the capacitors then that is a clue they may be bad.

    DO NOT let your system run if the either fan motor (inside or out) is not working you will destroy your compressor, the same goes if your unit is icing up or short of charge  you will burn up your compressor motor.

No control voltage: Most residential units use 24 volts ac to pull in the contactor. The power for this usually comes from a step down transformer in the furnace or indoor unit through the thermostat. Some outdoor equipment will have its own transformer, but this is rare for residential.

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Written By:  Scott Meenen N3SJH  of
Serving Maryland, DC, and Northern Virginia.

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Specializing in Mechanical, Controls and Electrical Modifications Of
Heating, Air conditioning, Refrigeration, Cold storage,
Ice Production and Food preservation.
Anything having to do with Heat and Energy.

We service and repair the following brands:
American Standard, Amana, Arco, Arco-Air, Bryant, Carrier, Coleman Evcon, Comfortmaker, Day/Night/Payne, Dunham-Bush, Fedders, Fredrich, Goodman, General Electric, Hotpoint, Heil, Intertherm, Janitrol, Kenmore, Lennox (Armstrong, Johnson Air-Ease), Miller, Modine, Nordyne, Rheem/Ruud, Sears, Stewart Warner, Trane, Williams, White-Westinghouse, Whirlpool, Weil Mclain, York, (Frasier Johnson/Borg Warner/Luxair) and others.