A/C problem - http://www.hvacmechanic.com/ Forums
Original message
| mikebobo
 |  "A/C problem"
, posted Mon 2 Jun 16:37  
Whenever the thermostat calls for cool, the compressor kicks on, but the blower fan does not come on. If I leave the blower fan switch on, it runs fine, but as soon as it calls for cooling the compressor starts and the blower fan shuts off. Any suggestions?
Mike
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Replies:
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| theduke03
| "Re(1):A/C problem" , posted Mon 2 Jun 17:58
Do you have a meter?
"My dad was the most feared furnace fighter in Northern Indiana."
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| | mikebobo
| "Re(2):A/C problem" , posted Mon 2 Jun 18:03
Yes I do.
Mike
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| | theduke03
| "Re(3):A/C problem" , posted Mon 2 Jun 18:52
Open up the indoor unit and look for t-stat wire connections. Set stat to fan on and a/c off. Check ac voltage from G to C. This should be 24v +/-. Then set stat to call for a/c. Check voltage again and see if it changes or drops when outdoor unit comes on. At this point I have several suspicions. Post results.
"My dad was the most feared furnace fighter in Northern Indiana."
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| | mikebobo
| "Re(4):A/C problem" , posted Mon 2 Jun 19:47
I'll check and post but it won't be till Wednesday or Thursday. Thanks!
Mike
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| | mikebobo
| "Re(5):A/C problem" , posted Thu 5 Jun 09:29
Ok tested the voltage, with everything off - nothing, with fan on at stat 28.2 V, and when A/C is kicked on, 27.6 V. Again when the A/c kicked on, could hear the compressor kick on outside, but the blower fan shuts down.
Thanks again!
Mike
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| | theduke03
| "Re(6):A/C problem" , posted Thu 5 Jun 18:40:
Mike your problem is most likely in the indoor unit. Can you tell me the make and model of that unit?(furnace or air handler) You will need to check if blower is getting voltage when problem happens. If so then it would be a bad motor or capacitor. If not then it will be a control(circuitboard or relay).
That wouldn't be a Trane or American Standard furnace would it?
"My dad was the most feared furnace fighter in Northern Indiana."
[this message was edited by theduke03 on Thu 5 Jun 18:43] |
| | mikebobo
| "Re(7):A/C problem" , posted Thu 5 Jun 23:45
It is an American Standard horizontal furnace model DD080C936B. It sits in the attic of the house. I know the controller is a White Rodgers model 50A50-405. I don't think the blower motor is bad because it will come on with the heat setting or with the fan switch on and it works fine until it calls for cooling. Then the fan shuts down, even if the fan switch is on. I assume there is no power to the blower motor when the stat calls for cooling. Also, the controller has a light to indicate trouble, but it does not indicate a problem when this happens. It has the normal blinking light.
Thanks!
Mike
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| | theduke03
| "Re(8):A/C problem" , posted Sat 7 Jun 08:41:
Ok I believe it may be the circuitboard. Do this: Remove the Y thermostat wire from circuitboard. If that works then replace the board.
Post results in a new thread so I won't have to search archives to locate you.
"My dad was the most feared furnace fighter in Northern Indiana."
[this message was edited by theduke03 on Sat 7 Jun 08:42] |
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