Carrier A/C - Compressor running but not pumping

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Old 07-12-10, 06:04 PM
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Carrier A/C - Compressor running but not pumping

Hi all,

I have a Carrier Heat Pump (3 ton), which is about 11 years old.
The A/C worked fine until yesterday when no cold air was coming out from the vents. It is blowing mostly warm air.

The A/C seems to run fine, outdoor fan runs, and the compressor seems to run fine as well.
But the compressor is not pumping cold air...

Is there any way to repair such problems without going to the extreme of replacing the compressor? Money is very tight these days... I would appreciate your answers.

Thanks!
 
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Old 07-12-10, 06:09 PM
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Originally Posted by absolute010 View Post
The A/C seems to run fine, outdoor fan runs, and the compressor seems to run fine as well.
But the compressor is not pumping cold air...
More info required. Is the indoor fan running?
 
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Old 07-12-10, 06:13 PM
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Originally Posted by Mike Speed 30 View Post
More info required. Is the indoor fan running?
Yes, indoor fan running as well.
 
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Old 07-12-10, 07:06 PM
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Originally Posted by absolute010 View Post
But the compressor is not pumping cold air...
Put your hand on the liquid line (the small one) and the vapor line (the larger one) to the compressor unit. Tell us the relative temperature.
 
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Old 07-13-10, 08:14 AM
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Originally Posted by Mike Speed 30 View Post
Put your hand on the liquid line (the small one) and the vapor line (the larger one) to the compressor unit. Tell us the relative temperature.
Update: I turned on the AC this morning and went outside to look at the lines as you said...
BUT now the outside unit is not working!
The outdoor fan is not running and the compressor is not running. The unit simply makes a low mechanical buzzing/humming sound.

I felt the liquid line and it is normal outdoor temperature.
The vapor line was a little cool (only cooler compared to the liquid line).

Any ideas what happened with my AC?

Thanks.
 
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Old 07-13-10, 08:34 AM
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Originally Posted by absolute010 View Post
The outdoor fan is not running and the compressor is not running. The unit simply makes a low mechanical buzzing/humming sound.
Is the indoor fan still running?

First, check that you have 24V to the solenoid terminals of the contactor in the compressor unit. If that checks out, then...

Carefully, with a voltmeter, make sure you are getting 240V on the load side of the compressor contactor. If so, then I would suspect the capacitor.

If you aren't getting 240V on the load side of the contactor, see if you have 240V at the line side of the contactor. If so, that indicates a bad contactor.
 
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Old 07-13-10, 09:14 AM
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Originally Posted by Mike Speed 30 View Post
Is the indoor fan still running?

First, check that you have 24V to the solenoid terminals of the contactor in the compressor unit. If that checks out, then...

Carefully, with a voltmeter, make sure you are getting 240V on the load side of the compressor contactor. If so, then I would suspect the capacitor.

If you aren't getting 240V on the load side of the contactor, see if you have 240V at the line side of the contactor. If so, that indicates a bad contactor.
Yes, the indoor fan is running because I can hear the sound.
Same sound as when it was running normally.

I don't have the tools to check for voltage... so I guess I would need to call a technician.

What would you say is a fair price for
- replacing a capacitor and
- replacing a contactor


Thanks!
 
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Old 07-13-10, 09:54 AM
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Originally Posted by absolute010 View Post
What would you say is a fair price for
- replacing a capacitor and
- replacing a contactor
You'll have to pay at least for an hour's labor and trip. You can ask what that is from whomever you call, but maybe figure $100+, depending upon location. A replacement contactor or cap might cost about $20, or so, plus maybe some mark-up.

But the hooker is that there seems to have been another problem before your compressor totally conked out this morning, right?
 
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Old 07-13-10, 04:50 PM
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i think your compressor is shot...short to ground. and im guessing that your condenser is plugged up with dirt in the liquid line filter. either that or perhaps the compressor is running backwards? are any of your circuit breakers popped?
 
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Old 07-13-10, 06:01 PM
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im in the same position can anyone help
had a tec look at my machine about a month ago and he said it was workin properly but now as the temp has risen outside my house isnt coolin down.

can any one help thanks
 
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Old 07-13-10, 06:33 PM
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Originally Posted by mr jrwhite View Post
im in the same position can anyone help
You've hi-jacked this thread. Start your own thread with all of your particulars.
 
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Old 07-14-10, 09:57 AM
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Could it have lost its Freon charge?

Originally Posted by absolute010 View Post
Yes, the indoor fan is running because I can hear the sound.
Same sound as when it was running normally.

I don't have the tools to check for voltage... so I guess I would need to call a technician.

What would you say is a fair price for
- replacing a capacitor and
- replacing a contactor
Thanks!
The cooling check valve could be open so the cooling mode expansion valve is bypassed.

Could it have lost its Freon charge?
That would open a low pressure switch.
 
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Old 07-14-10, 08:15 PM
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Update:
I called a technician today to look at the AC.

The first problem, which was very simple, was that the capacitor had died. So he replaced the capacitor and the AC runs.

The second problem is still unsolved.
Even after replacing the capacitor, the AC did not blow cold air.
So he checked for freon and said there was plenty.
He checked for a variety of things but in the end he could not find what the problem was.

Everything was running in the AC...

He showed me the pressure measurement.
The blue-colored one was measuring too high when he said it should measure around 70, but it is getting over 200-ish.
The red-colored one was measuring too low when he said it should measure around 250, but it is getting only 60-ish.

He said the readings are reversed but did not know why.
He said there's a strong possibility that the compressor is the problem but not guaranteed.


So I am still left with a bad AC in this summer heat...
Any advice for me?
 
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Old 07-15-10, 07:40 AM
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EDIT:
I wrote it down on paper and below is the correct measurement.

The blue-colored one was measuring 150-ish. (high pressure)
The red-colored one was measuring 120-ish. (low pressure)
 
 

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