a/c not working

phild01 · 04-10-2008, 01:10 PM

My central a/c is not blowing cool air at all. The outside fan is running and there is an icy buildup on the lines. I turned the unit off at the thermostat and the out fan is still running. Pulled the fuse to stop it. After ice was gone reinserted the fuse and fan came on with the unit still on off. I had the inside unit's coils cleaned about a year ago. Inside filter is clean. The unit is about 15 years old.

Any ideas.

Thanks

Phil in Miami

HvacWiz · 04-10-2008, 07:22 PM

sounds like the compressor contactor is stuck closed

HVACman · 04-10-2008, 09:35 PM

First thing, if you don't feel comfortable opening the service panel on your condenser outside, call a pro. Find the contactor, similar to the pic here. The pic is a single pole contactor, yours might be a dual or look a little different but when the thermostat calls for cooling the furnace/air handler inside sends 24V AC to the coil on the contactor and pulls down the contactor causing the condenser fan and compressor to start(spot marked with an "X" in the pic) When this coil gets stuck in the closed position the outdoor unit never shuts off and causes the condenser to freeze up. This can burn up your compressor. When you replace the contactor, pull the disconnect/fuse outside and make sure that the thermostat is set to off so that you don't have 24V AC coming to the contactor coil. Let me know how it turns out.

phild01 · 04-10-2008, 10:16 PM

my wife just noticed water on the garage floor. I took off the 2 panels, one covering the coils and the other, the air intake manifold? There was ice on the coils. Right now the ice is melting and water is coming out the drain. I added a bottle of Nu Line. Is this another symptom of the compressor contactor not working or is it a bigger problem.
I'll pull the cover off the condenser in the morning and check it out

thanks

phil

HVACman · 04-10-2008, 10:56 PM

If the condenser coil froze up outside, it's a good bet that the evaporator coil inside also froze up. It all needs to be totally defrosted and dry before you start it back up. Let me know what you find.

phild01 · 04-11-2008, 12:38 PM

Problem solved. Took off the condenser cover and and checked the circuit. I had power to the unit even though the unit was off. Was drinking my coffee and thinking about what it could be. The new thermostat I installed 2 months. I never put the other screw in because I was going to patch the wall. Timed passed and every once in awhile I would straighten out the thermostat. Turns out two wires were touching. Fixed the box properly, turned the unit on and it worked. Another lesson learned.

thanks for the advice. You put me on the right track.

phil in "cool" florida