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Author Topic: central ac not keeping up  (Read 3775 times)

Offline jrgreene1968

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central ac not keeping up
« on: June 27, 2009, 07:33:00 AM »

I have a comfortmaker 4 ton ac unit, thats 2 years old, The system works great,,until it reaches 95 out, then the indoor temp slowly rises. I have my thermostat set at 75, the ac cycles on off just like its supposed to, until it reaches 95 out, then it stays on and dont seem to keep up, until around 9 at night.  We have been having 101 to 103 temps here all week.

I have had the system checked out 2 times, both times, company says its all it can do, and everything is fine. The unit is actually a 1/2" ton larger than old unit, so i thought it should do better . My question is..all the pressures seem good, unit has 5 degree superheat (@100 outside) 7 degree subcooling. But my delta temps at supply and return grills is only 15-16 degrees. Ive been told 20 degrees is the magic number. Fan speed is on high, Any ideas why my delta is low, and what i could do to help the situation.

Thanks in advance

Offline JWWebster

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Re: central ac not keeping up
« Reply #1 on: June 27, 2009, 11:03:35 AM »
Maybe you ought to put some attic ventilators in. At these higher temps the attic is like an oven. Your bill will drop a lot if you put some in. If you already have them in you might need to check them.
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