Central air blowing room-temperature air (not cold)


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Old 07-22-04, 03:17 PM
mattian
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Central air blowing room-temperature air (not cold)

I have a Carrier Heat Pump (1986) and a few days ago it stopped blowing the nice cool air we like so much and will now only blow room-temperature air. Apart from the house being hot, I'm sure my energy bill will be sky-high since the the thermostat never lets it stop running.

The fan outside is turning. I have switched off the breaker and switched it on. The insulated 1.5" to 2" pipe from the pump to the house is not cold (I don't know if it's supposed to be) - its temperature is at regular air temperature (much like the air coming out of the vents :-/)

Anyway - I have replaced the filter - and now I'm at a loss; still not getting any cold air.

Other info: I'm in a two story townhouse with a walkout basement. The basement vents are fully closed, the ground level vents and the upstairs vents are fully open - to try and regulate the temperature throughout the house. This was working quite well when the air conditioning was actually working.
Please help. Thanks.
 
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Old 07-22-04, 04:07 PM
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If the outdoor fan is working, you know that you have power. However, it sounds like the compressor is not running. There could be several reasons for that and it is probably worth having a tech come out and fix it. Most likely if the compressoe is bad, they will recommend replacement of the outdoor unit. If the problemis a capacitor or burned wire connector or something relatively simple, they can just repair that and get you back running again. I would suggest being there during the service visit to verify the defect. Don't let the age of the unit be the exclusive reason for replacement but don't throw good money after bad either.

Ken
 
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Old 07-22-04, 04:16 PM
mattian
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Thanks for the input, Ken. I keep feeling the air exiting the vents trying to pursuade myself that air coming out of them is cold. I fear I've lost my perspective here and am no longer able to discern cold air from air at room temperature. I'm sure the effectiveness of air conditioners varies as a function of time for a given unit, based on factors such as how hot it is outside, the humidity, etc. Without relying entirely on my own judgement, is there any way that I can verify that the air from the vents is within acceptable temperature range? At the moment, my thermostat reads 82 and the setpoint is 74. Over the last few hours - since I've been troubleshooting this problem - it hasn't changed, and of course the air has stayed on constantly. How do I know that it's not performing at all vs. simply performing badly?
 
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Old 07-22-04, 04:52 PM
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Wink

Feel the copper pipes out by the unit. The big one should be cold and wet the little one warm like. See if you have a hum from the unit with the fan there blowing.

ED
 
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Old 07-22-04, 06:10 PM
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We like to see a 20 degree F drop over the coil but humidity and other factors come into play too. If you are getting 15 degrees, you should probably be OK. Measure air entering a return grille and air coming out of a supply grille. You can use any thermometer you have that goes from 50 degrees F up.

Ken
 
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Old 07-22-04, 07:00 PM
mattian
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I think I need a tech to have a look. The pipes are regular air temperature. I will listen for the hum and compare the inlet temp to the outlet temp tomorrow.

Thanks Guys.
 
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Old 08-04-04, 06:40 PM
mattian
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Okay - tested the pipes outside. They're both (the thinner one and the thicker one) the same temperature - a little colder than air temperature (because they're metal). The thick one is not cold and the thin one is not warm - they're the same. At a glance, what conclusions could I draw from this?
 
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Old 08-04-04, 08:15 PM
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It would be helpful to determine if the compressor is running. That will probably require removing panels and possibly taking voltage measurements. If those things are out of your capability, you should call a tech to get the whole picture. It may not be all that serious but you need to check quite a few things to be sure.

Ken
 
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Old 08-09-04, 03:53 PM
mattian
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What voltage measurements should I take? The voltage across the compressor?
 
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Old 08-09-04, 04:32 PM
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It would get to the source most quickly if you checked the voltage at the compressor. The easiest way to get started would be to check the voltage on the load side of the contactor. You should get 240 volts. While you ar ein there, check if the compressor is hot or not. If it is, did you notice if it made any noise while you were checking the voltage? Like a click or hum or buzz. If it is too hot to touch, turn the unit off for a day and check for sounds then. Sometimes the compressor gets so hot that it takes several hours for the internal cut-out to reset. And it won't make a sound while that is happening.

Ken
 
 

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