AC blows warm during heat of the day, blows cold at night

Problems related to residential installations.

AC blows warm during heat of the day, blows cold at night

Postby slimrob » Wed Jun 01, 2011 7:27 pm

This seems like a great service. I'm glad a came across it.
I am having an issue with my AC at home. My air handler is a westinghouse and was installed about 2 years ago. My outside condenser is a goodman unit, 2 ton, and that was just installed 2 months ago. Right now, my AC seems to do well except during the hottest hours of the day it seems to blow warm air, and the temperature gets to about 82 degrees inside, even though it is set on 76. I have replaced the filter and changed the batteries in the thermostat.

I did have someone come out and look, and they discovered a freon leak in the coil of the air handler. I believe they said the pressure was 65 pounds, but that it should be 75. Even under a parts warranty, this will cost over 1000 dollars. Was just curious if leaks are normal, and maybe there is a separate issue that is cheaper or easier to solve? Seems strange to have to fork over all this cash with such new equipment that I just bought! Thanks much for your help!
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- AC blows warm during heat of the day, blows cold at nigh

Postby 4ftBanger » Sat Jun 04, 2011 5:36 pm

Personally, I'd be looking for another estimate - Rates vary so it depends on your area, but In coastal Virginia I haven't done an indoor coil replacement that I would value at $1000 .

Your original issue could be a symptom of low refrigerant - An AC unit relies on the refrigerant to cool the compressor motor... so a low charge could cause the motor to overheat and trip the internal overload safety switch shutting the compressor off. If so, then it makes sense that the AC would work fairly well when it is cooler outside... until the compressor overheats.

Keep in mind that the typical design for a NEW single stage comfort cooling system is about a 20 to 25 degree difference from outdoor air to indoor air, and AC coils will lose their heat transfer capability over time. So if its above 96 outside your AC might not have enough capacity to maintain 76 inside.

Low side pressure is not a fixed value. A good service tech will never reference pressure alone... We convert the actual pressure to a "saturated temperature" and compare that with the actual temperature to determine superheat and subcooling. This tells us if the refrigerant charge is right or not. I'd be suspicious of a service tech that only references pressure in the diagnosis.
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- AC blows warm during heat of the day, blows cold at nigh

Postby nomadpeo » Sat Jun 11, 2011 4:11 pm

what is the age of the evaporator coil (inside) ? i agree with 4ftbanger. get a second opinion and another quote.
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- AC blows warm during heat of the day, blows cold at nigh

Postby Freon » Sat Jun 18, 2011 1:04 pm

As has been suggested, get a 2nd opinion and IF you're told there is a leak in the indoor evaporator coil, have the tech SHOW you where it is. Depending on the age of the coil and the location of the leak, it may be cost effective to fix the coil.
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- AC blows warm during heat of the day, blows cold at nigh

Postby nomadpeo » Tue Jun 21, 2011 10:00 pm

evaporator coil repair is rarely an option. many times, the leak is in a place embedded where it cannot be accessed. i'm assuming it has some age on it. the new coil will be stronger because new coils are also rated for the new refrigerant, which runs 100 -150 psi higher pressures. in houston, that 1000 range would be about average for a fair job. there may also be modifications, such as a transition. the filter/drier will need to be changed. whenever a condensing unit is changed, the coil should be evaluated and at least leak checked. the ducts should be looked at. the whole system should be looked over for possible causes for the compressor failure. think twice before using the same contractor who condemned the condensing unit or the contractor who installed the new one if they are not one and the same. while you don't want to buy something you don't need, you should welcome information regarding your system as a whole.
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