DIY Home Improvement, Remodeling & Repair Forum > Appliances > HVAC > Carrier central air unit won't come on.




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Old 10-05-2007, 08:26 PM  
kozakid
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Default Carrier central air unit won't come on.

I have a Carrier central air unit which came with my new house eight years ago.

Today I started feeling warm and that's when I noticed that the central air unit was not running. At the moment it's over 80 degrees inside the house.

I always keep the thermostat (White-Rodgers) settings as follows:

FAN: Auto

SYSTEM: Cool

Today I turned the unit off. Then I went outside by the unit and had someone inside the house turn the unit to the above settings. Whenever they turned the unit on, I would hear a single click, but that was all. The unit did not turn on.

I checked the attic unit pan and noticed that while the pan floor was wet there was no measureable amount of water in the pan. (See below.)

I've had similar problems in the past. At those times I would turn the unit off for at least five minutes and then turn it back on, and usually the unit would turn on and cool the house normally. Sometimes I had to do this more than once in order to get it to turn on and work normally. Also at these times, whenever I checked the attic unit pan I always noticed approximately three-quarters of an inch of water in the pan. As mentioned above, today there is not a measureable amount of water in the pan.

I would greatly appreciate hearing from anyone who might be able to help me get my central air unit working again. Thank you.



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Old 10-06-2007, 05:49 PM  
glennjanie
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Hello KozAKid and Welcome;
A quick, down and dirty way to check the unit is to remove the inspection panel outside and find the contactor. Keeping yourself in the clear, take a plastic handle of a screwdriver in your hand and use the other end to push on the center of the contactor. If the fan and compressor kick in you may have a bad electro-magnet in the contactor. Cut the power off, remove the contactor and take it to the A/C supply house for repair or replacement.
If the fan and compressor do not kick in, it is most likely a blown fuse. There should be a disconnect in arm's reach of the unit which, in some cases, has cartridge fuses in it. There are two ways to check them, 1. use a voltmeter to touch both sides of the Line, it should read 210v or more; now take the voltmeter and put it on top of one fuse and the bottom of the other, reverse it. This checks the fuses without one getting backfeed. 2. Take the fuses out of the box and use an ohmmeter from one end of the fuse to the other to see if there is continuity.
If the fuses check out and nothing is wrong with the contactor, and the two pole breaker is on in the main panel, cut the power at the main and procede.
Get inside the compressor housing, take the spring clip off the junction box on the compressor, disconnect the 3 wires. Use the ohmmeter from a ground on the compressor to each of the 3 connectors on the compressor, record the reading of each pole. One of them should have the same reading as the total of the other two poles. If that doesn't prove out, there is a short in the compressor and it needs a new one. However, if it is a short in the compressor the fan would run without the compressor running.
About 8 out of 10 A/C units I have serviced had a wire burned off in the outdoor unit, if that is the case cut the burned wire off, strip it , put a new end on it and reconnect it.
I realize I have written a book on this one and you may need to print it out to go through all the steps I have outlined. Start by looking for the burned off wire. Best wishes and let us know how it turned out.
Glenn



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Old 10-17-2007, 10:52 AM  
kozakid
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Thank you very much for your prompt response, and I apologize for my late reply.

I had my AC unit repaired several days ago. As you suggested in your first paragraph, the problem was a bad contactor. $193.43 total cost. (materials: $124.3; labor: $59.00; travel/fuel charge: $10.00). The guy was here no more than 30 minutes. Of course, I haven't had maintenance on the unit over the eight+ years I've been here, so I guess that's not too bad. (I believe he said the freon was okay.)

He mentioned that the cost of a new unit is between four- and eight-thousand dollars. Also, he said his experience tells him that the life-span of a unit is between 10 and 15 years, while the industry claims only 8-12 years.

I truly appreciate your helpful suggestions, and if I'd been the handyman type I'm certain I would've followed your instructions and done it myself, figuring I probably would've saved myself a few dollars in the process. Ordinarily I could've called upon my brother-in-law, but he hasn't been availabel for a while. At any rate, I'm thankful the problem wasn't more serious and costly.

This is somewhat off topic, but I mentioned to him that I had a new sprinkler system and asked his opinion of having a separate meter. He said I might instead want to consider a shallow well. He went on to say that he and his father had dug one in his yard to use with both his irrigation system and his swimming pool. Then he wondered if there might be in-town or in-subdivision restrictions on well-digging for my town and subdivision. Anyhow, maybe that's something at least worth looking into.

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Old 10-17-2007, 10:02 PM  
glennjanie
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Hey Kozakid:
I don't know about Gerogia law but Kentucky is very sticky about it. My geothermal unit uses 3 150' deep wells and a friend with the Watershed Department perked up when I mentioned them. He backed off when I explained they would be drilled and refilled the same day. You might check around before the stuff hits the fan.
Glenn

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Old 10-18-2007, 08:36 AM  
kozakid
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Quote:
Originally Posted by glennjanie View Post
Hey Kozakid:
I don't know about Gerogia law but Kentucky is very sticky about it. My geothermal unit uses 3 150' deep wells and a friend with the Watershed Department perked up when I mentioned them. He backed off when I explained they would be drilled and refilled the same day. You might check around before the stuff hits the fan.
Glenn
That sounds like good advice. Thank you.


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