My Carrier 38CKC central a/c unit stopped cooling during the recent high-90's weather. The fan on the external unit runs when the thermostat is set to turn the a/c on, and the compressor sounds like it tries to start for a second, but then it immediately stops. It tries again to start about every 30 seconds, but never succeeds. The unit is about 7 years old. Any thoughts on what's going on?

Could be a bad start relay or start capacitor.
Could be a bad run capacitor.
Could be a bad wire on one of the compressor terminals.
Could be a bad compressor but check the other items first.

Thinking if it had a burned or bad wire not making contact,, it would be trying to start

Quote:

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Originally Posted by hvac1000

Could be a bad start relay or start capacitor.
Could be a bad run capacitor.
Could be a bad wire on one of the compressor terminals.
Could be a bad compressor but check the other items first.

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Thanks for the ideas. I'll check the capacitors and compressor terminal wires and see if I can figure out what's going on.

The run capacitor is good. I tried a large start capacitor (~160uF) with no luck. The wires look good, and the start motor appears to be drawing a lot of current when it tries to start the compressor. Perhaps the piston is stuck in the compressor. If so, would hitting the compressor with a hammer or something knock the piston loose? Bottom line, I'm probably looking at buying a new compressor. Since it's R-22 based it looks like this won't be cheap.

How old is the unit? May want to think about complete replacement rather than just a compressor,, you are probably looking at $800.00 there abouts for just compressor replacement,,

I got some quotes:

$3000 for compressor replacement (for current SEER 10 Carrier)
$4000 for new SEER 13 unit (Carrier Comfort series)
$5000 for new SEER 15 unit (Carrier Performance series)

All are 2 ton (24,000 BTU/hr)

Compared to the prices I was quoted that $800 compressor is sounding pretty good. Where can I find one of those?

$3000 for compressor replacement (for current SEER 10 Carrier)

The above price is WAY OUT THERE.

Here is the problem. Replacing the compressor is not something you can really do. In other words they do not send a rookie out to do compressor replacements from a HVAC company.

Way too much involved to type here + you need a certificate from the EPA to administer the removal and recharge of the refrigerant. Recovery machine, vacuum pump and other tools cost more than the compressor to start with so you will have to make a big$$$$ investment to change one compressor.

Take a block of wood (2X4) and place it on the weld lip midway up the compressor. (this is a strong area). Use a good size hammer or mallet and give it a wack or two. If that fails get some more estimates. If it works get some Supco 88 in your system right away. It is the best lubricant available for stuck/damaged compressors rings. A compressor replacement has to be much cheaper than what you were quoted.

Did you check the start relay to see if it was good. You can have the best start capacitor but with a bad relay it will make it useless.

Juhraffe,

My A/C just started having the same symptoms. I did notice however that when I allow it to cool off for a few hours that it will kick on and work for a while but when it heats up the compressor will go back to that routine. Had a tech come out, he said he had to replace a part that had already been replaced once before... he was supposed to call me back with the price of the part but never did. I personally replaced the delay timer before but am not sure if some one else had replaced something before me... the capacitors label is totally worn away but I'm thinking might as well replace that too. Maybe you can try that.

Sam

Why does ac compressor take 2 to 3 minutes to start?