A/C Not holding temp down during day.

**vaderss** · 06-09-2004, 11:04 AM

I just bought a 2 story 2400 sq.ft. house and I find that, even if noone is going in and out during the day, the A/C can't maintain 74F during the day. On a sunny day, the temp will creep as high as 80, starting from 74 in the morning, before the evening comes and it starts to cool down again. The A/C is a single York and I don't know the size or age of the unit. Where do I look for this info? I do know that the filter for the return vent is a 20x30, and I think it is too small, since a new filter is bowed up from airflow as soon as it is put in place.

I have a 609 cert and have been doing automotive A/C for over 10 years, but I don't know much about HVAC. I am assuming the refrigerant is R-22, since my R12/22 manifold gauge connectors fit. The pressures last night, with it being 76 in the house and 82 outside, were 60 and 165. I was wondering if this indicates a problem such as low refrigerant.

We have a home warranty, so I can will call them if I have a problem, but I'd like to know a little about the problem before calling them in.

Thanks,

**slice** · 06-09-2004, 12:14 PM

low on r-22.

**hittman** · 06-09-2004, 02:04 PM

Most likely low charge,if so you have a leak and the home warranty co. will just want to charge the unit up,this may last through the warranty. then next year it will need freon again.Ask the service Co. to find and repair the leak.

**flechtight** · 06-09-2004, 03:49 PM

do not forget superheat and subcooling measurements, pressures pressures alone do not tell the whole story

**h2045** · 06-09-2004, 03:55 PM

Short on juice!!!!!!!! At 82* outdoor temp your head should be around 220# - 230 #

**smokin68** · 06-09-2004, 06:56 PM

Originally posted by h2045
Short on juice!!!!!!!! At 82* outdoor temp your head should be around 220# - 230 #

That's not always true. I just checked one that was 205psig at 92 ambient. You need the subcooling/superheat measurements to know what's going on in the system. That 160 head pressure sounds low,but the suction isn't far off. Don't just ASSUME it's short of freon.

**beenthere** · 06-09-2004, 07:00 PM

I would have the duct system checked. It also sounds like you may have an air flow problem.
After that is checked, and fixed if not right, the refrigerant part of the system can then be checked acurately.

**vaderss** · 06-09-2004, 10:02 PM

Thanks all!

If it's flow I'll have to hire someone because the warranty specifically excludes installation issues. I've got a bad feeling about that though. That return is only 33% bigger than the one in my old 2 bedroom apartment and it seems like it's pulling way to much dp across a new filter. Guess I'll get the warranty people out and have them tell me exactly what is wrong. If I have to hire someone, I have to. The electric bill will eat me alive otherwise...

Measured the pressures again today at 87F outside 77F inside and they were 185/65.

**hittman** · 06-09-2004, 11:20 PM

Originally posted by hittman
Most likely low charge,if so you have a leak and the home warranty co. will just want to charge the unit up,this may last through the warranty. then next year it will need freon again.Ask the service Co. to find and repair the leak.

vaderss
My point is, if it is low on freon have them fix the problem or you will be paying out of your pocket when the warranty is gone next year.

**robinair** · 06-10-2004, 06:11 AM

find one of only 5 contractors in the free world that can read total external static pressure and CFM . Tyou will be amazed at what you find.
yeaterday i measured a system that had been condemmed as too small by 3 other comapanys . this was a 3 ton system capable of 1200 CFM with perfect static pressure. it was actually only producing 855 CFM. We made 1500 bucks worth of duct modifications and guess what ? the undersized system works great .
good luck on finding a duct-oligists we are a dying breed .

**vaderss** · 06-10-2004, 07:04 AM

Hittman, I understand what you are saying. I'll make sure they fix the leak if it's low on refrigerant. I know all about people charging for the summer and not worrying about where the leak is.

Robinair, any reccomendations as where to look? I'm in Houston. Seems like I'd have a decent shot at finding a good one.