How to Troubleshoot a Residential A/C Compressor
Carry out some simple procedures every spring to keep your home air conditioner operating at peak efficiency. These include cleaning the drain pan under the air handler located in the attic, flushing sludge out of the air handler drainpipe and clearing grass cuttings, leaves and debris from the cooling fins on the external condenser unit. If and when your system appears to lose its cooling capacity, run a few diagnostics before scheduling an HVAC service call; you may save some money by correcting the problem yourself. Does this Spark an idea?
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Things You'll Need
- Thermometer
- Screwdriver
- Stiff wire
- Rag
- Shop vac
- Bucket
- Trigger spray nozzle
- Garden hose
Instructions
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1
Switch off the air conditioner and let your home warm up. Make a note of the ambient air temperature reading on the thermostat.
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2
Set the thermostat to 65 degrees Fahrenheit, then turn the air conditioner on and wait 15 minutes.
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3
Place a thermometer in front of the air conditioner inlet vent and wait a few minutes. Compare the reading with the previous ambient air temperature reading; the difference between the two should be about 20 degrees Fahrenheit. If the room has warmed up even more, go to the next step.
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4
Climb into the attic and inspect the outlet tube under the air handler cooling coils that lead to the drip pan below the unit; you may have to remove an inspection panel with a screwdriver to gain access to the tube and the pan.
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5
Turn the air conditioner off if you notice ice on the drain tube and around the coil and wait for the ice to melt; the outlet tube on the drain pan is probably blocked, causing the ice buildup and lower the air conditioner's efficiency.
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6
Clean out the drain pan and remove any accessible debris and sludge from the neck of the outlet drainpipe with a piece of stiff wire.
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Go outside and locate the drainpipe leading from the drip pan; this pipe is either sticking out of the ground or protruding through the wall somewhere near the outdoor condenser unit.
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8
Wrap a damp rag around the pipe to act as a gasket and place a shop vac hose over the drainpipe. Turn the shop vac on and suck out any sludge that is blocking the drain.
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9
Go back into the attic and pour about a pint of drain cleaner down the drip pan drainpipe. Wait a few minutes then pour a bucket of hot water into the drip pan to clean out the drainpipe.
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10
Climb down and turn the air conditioner back on. Wait another 15 minutes then check the thermometer in front of the inlet vent to see if the room has cooled by at least 20 degrees. If this has corrected the problem, check the thermostat reading; if it hasn’t moved, the thermostat is faulty and must be replaced.
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11
Go outside and hold your hand on top of the condenser unit to verify that the fan is working if the problem persists. If you don’t hear the fan or feel air blowing out the top of the unit, schedule a service call; but if the fan is working, go to the next step.
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12
Turn off the power to the condenser unit by opening the waterproof electrical junction box on or near the unit and tripping the switch.
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13
Attach a trigger spray nozzle to your garden hose. Press the trigger and direct the spray onto the outside of the condenser unit in a downward direction. Work your way around the unit to wash out any grass cuttings or debris blocking the condenser cooling fins.
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14
Turn the power back on to the condenser unit and wait 15 minutes before going indoors. Check the temperature difference as described above. If the air conditioner is still blowing warm air, call an HVAC technician; you may have a faulty compressor, some other component may have failed, or the system may need to be recharged with refrigerant.
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References
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