A/C unit does not start

mrshah · #1 Jul 10, 2007, 08:49 AM

I have a lennox A?C unit installed model #10ACB30-5p. Its a 10 year old unit. It was working fine until last saturday when i noticed that the blower is blowing hot air. i checked the unit outside and the Fan and the compressor were not running. I shutdown the thermostat and re-started it and the fan and the compressor started running and it stared blowing cool air. It happened again last night and now it wont start the fan and the compressor even after turning on and off the whole unit. I opened the unit up but could not find anything wrong. I noticed that as soon as i turn on the thermostat, something clicks in the unit and the capacitor and the contactor buzzes continuously. I am suspicious that either one of them is faulty. i did not find any fuses in the unit. Any help to diagnose the problem will be appreciated. I pray its not the compressor which has gone bad. Let me know if i need to replace the thermostat.

Thanks
SS

esquire1 · Jul 10, 2007, 09:08 AM

Shut power of to unit and look between the contacts. Sometimes bugs will get in between them. With power on push in on contactor with screwdriver. Be carefull. Now doest the conpressor and fan come on? Also with power to unit take srew driver and spin the fan. Does it start up now?

mrshah · Jul 10, 2007, 09:18 AM

Thanx for a quick reply. I am at work right now so as soon as i get home, i will try that. lat night i cleaned all the contacts and they looked fine. I never pushed the contactor with the screwdriver. So i will try that and let you know. Thanks again

mrshah · Jul 11, 2007, 07:46 AM

Hi,
I tried pushing the contactor and the fan with the screw driver with the power on but it did not start the fan or the compressor. I could feel voltage in the contactor. I dont what is wrong.

esquire1 · Jul 11, 2007, 07:55 AM

You need to check to for 220volts coming into contactor. If nothing happened when pushing in either no voltage or something between contacts. Have you check fuses at disconnect and breakers? Many times breaker look like they are on but not really. You need to move all the way over then back on. Don't quite understand how you could feel voltage at contactor. You didn't get bit did you?

mrshah · Jul 11, 2007, 07:58 AM

When i said i felt the voltage, i meant i could feel the vibration on the screwdriver and i think this was caused by a higher voltage. I did not see any fuses in the unit can you please tell me where i can find it. Also when you say a breaker, does it mean the main circuit breaker for the A/C unit.

Thanks for a quick answer.

esquire1 · Jul 11, 2007, 08:04 AM

Yes, In breaker box the one for A/C. You may have a disconnet box mounted on house right next to condensing unit within arms reach. If you have one there, it will have 2 fuses in it. Do you have a mutimeter to do some testing? This cannot be too difficuilt to get going. Glad to hear you didn't get bit. Had me concerned. Work safe.

mrshah · Jul 11, 2007, 08:10 AM

Right next to the AC unit there is a box which has a huge fuse in it, and it does not seems to have shroted out. i will use the multimeter and test the voltage to the conductor.

Thanks

mrshah · Jul 18, 2007, 07:47 PM

Hi
I called an AC repair guy and he looked at the AC unit and checked the voltage in and out. He said he suspected a bad compressor but he was not sure. So he started opening things up and cleaning them. He oiled the fan, cleaned the compactor and the capacitor and the powered on the system and to my surprise the unit started. He tested the unit by shutting it down and restarting 3-4 times and now suddenly the unit seems to work fine. He was there for about 2 hours and i paid him $65, pretty good deals coz hez knows one of my buddies. Well, next day oi came back from work and to my surprise the unit was not working again. I got pissed. Went out and opened the unit, removed the fuse, the again started clenaing the compactor and the capacitor with an old tooth brush. after cleaning the unit, i started it again. This time it started again. I called the AC repair guy, he said lets replace the capacitor. He got me a capacitor for $15 and i replaced it myself and touch wood the unit has been running without any problems since 6 days. Hope this info helps other members.

Thanks

SS



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