Let's talk home A/C troubleshooting...

[Dude]

My house is hot. During a 90-95 degree day, I cannot keep the interior of the house below 80 degrees. For me, it is miserable. I don't know much about this A/C unit but it is brand new in late 2005 and it IS big enough where it should cool our 1600 sq. ft. But it doesn't. I had an argument with the A/C service tech today, he said it is working fine, good on freon and we are getting 66-70 degree air from the vents.

It just can't keep up during the heat of the day, and then it doesn't catch up until the next morning, before the heating of the day starts all over again. Literally at 10 PM last night it was 80 in the house. WTF is wrong?

Personally, I don't think enough of the air is coming out of the vents to push into the rooms, but the A/C tech said the fan was fine.

WTF could this be?

 

[Bobby_M]

Do you have good venting in your attic? How much insulation do you have up there? Do you have any leaks in your ductwork? Are the ducts in the attic? If so, are they insulated?

Here's a surprising one.... did you confirm that your compressor is running the whole time the thermostat is calling for it? I've seen the power company put restrictors on compressors so that they only run 50% duty to save energy. They do it in condo complexes a lot and know a few people who had to call them to complain to have them removed.

Was this arguement with the AC guy that actually installed the system? I'd imagine so because they'd have to admit the totally F'd up on the load calculation and eat it on the upgrade.

 

[Tophe]

You should be able to get 18-20 degs temperature drop across your cooling coil If your return air is 80* you should be discharging close to 60* or so. If you had the a/c tech out, Im assuming he made sure your condenser is clean and was running when it should be. Is your air filter clean? These are the first two things to check that are simple.

Is your house shaded at all, or in the open sun? It's hard to trouble shoot without putting some gauges on your system. It is very possible that your system could be overcharged also. The only way to know is by hooking up gauges.

Also you said it doesnt seem like enough air is coming from your vents.... Your fan speed is adjustable, and should be on high for cooling. ...


Was it the same company that installed your system that came and checked it out today?

 

[BierMuncher]

I found I was able to cool my house more efficiently by dropping the thermostat down to like 70-72 at night (starting around 10:00PM). This ran until about 5:00 AM and the house was a lot easier to get cooled down at night. It was alos a lot more comfortable for sleeping. The next day my AC, when the thermostat returned to a normal 78-80 setting, it would not go on until late morning/early afternoon.

I'd say treat your house like a cooler...ice it down the nite before and close every shade in your house. Double check your individual duct dampers in the basement.

 

[Evan!]

You could tell them damn kids to stop leaving the door open...

 

[Reidman]

I'd make sure all your ducting is connected properly and your not venting cool air to your crawl space or attic.

 

[knewshound]

I had a similar problem until I replaced my entire POS unit.

With 2100 sq ft it will take it from 90 to 75 in about an hour.

You have a problem.

There is no reason you should have to run it as you do. I had to do the same thing with our old one, but it was vastly undersized (1.5 ton old one, 5 ton new one)

An independent evaluation by someone without an interest in it may be in order.


If nothing else it will at least give you peace of mind, which is cheap for the 50 bucks it will cost you.

Just my .02.

Cheers,

knewshound

 

[anthrobe]

I had a similar problem until I replaced my entire POS unit.

With 2100 sq ft it will take it from 90 to 75 in about an hour.

You have a problem.

There is no reason you should have to run it as you do. I had to do the same thing with our old one, but it was vastly undersized (1.5 ton old one, 5 ton new one)

An independent evaluation by someone without an interest in it may be in order.


If nothing else it will at least give you peace of mind, which is cheap for the 50 bucks it will cost you.

Just my .02.

Cheers,

knewshound

I just put a new one on my house last fall. So far this summer it is really working well. I am running a 3 ton unit for 1200 sf home. All of the previous replys covered anything that I thought of.

 

[sause]

At least up in my house we had to run a few fans to circulated the air to the upstairs. It's quite a bit cooler now since we did that.

 

[david_42]

Check the ducting for leaks and blockages. Check the insulation in the attic. Get some punks and check your windows and doors for leaks. Use this as an excuse to buy a no-contact thermometer and check the walls and ceiling.

When I moved to Oregon the ducting under the house leaked so bad that when you went into the crawl space there was a steady breeze. No insulation in the floor & 4" in the attic. Plus, there was an uninsulated duct running from the main inlet that ran outside, then down the interior of the chimney to some vents in the fireplace. I think the idea was to get more heat out of the fireplace. Did not work! Sucked in hot air in the summer and cold in the winter. Sealed the duct and vents, taped up the rest of the ducting & added 8" floor & ceiling. Worth every penny.

I get almost 20F across my system.

 

[Bobby_M]

At least up in my house we had to run a few fans to circulated the air to the upstairs. It's quite a bit cooler now since we did that.

I had the same issue until I got an electronic thermostat that lets you cycle the fan on for a certain number of minutes per hour. It helped to mix warmer upstairs air with cooler downstairs. I have it run the fan for 10 minutes each hour.

 

[Brewiz]

And along with all the other suggestions, make sure you have enough return air and that all the interior doors are open so your system can exchange the air in your house.

 

[Bobby_M]

Just to add to that, see if they put individual returns in the bedrooms. Sometimes they cheat by putting cutting the doors down on the bottom to leave a 1" gap but it's not as good as individual return trunks.

 

[Dude]

Well, the tech came back out in teh afternoon and realized why I called. The house was 80 degrees when he came back at 5:30 PM. So, he butt-raped me by upping the fan speed (5 minutes of work) and calling it a service call. The guy was a total ********.

After he left, I decided I need to vent my attic a little better. The vents are fine, but I think I need an exhaust fan up there. It runs about 15-20 degrees warmer than the ambient air temp inside the house--I think just 5 degrees lower up there may make a huge difference down below. I'm going to run a little experiment for the next few days and see if it even helps, before I go out and get a true exhaust fan hard wired into the house.

FWIW, the tech I called was NOT the original installer. I did that purposely--but didn't realize the company was going to be such a-holes.

 

[sullifan]

Dude-

No wonder the guy stole your money!! After a day of ladders, hot attics, dirty crawl spaces, and bitchy customers, AND seeing ALL of your goodies on his house tour, it doesn't sound like you even offered him a beer! Even tho you were PO'ed and he was working, an offer like that can certainly soothe the savage beast! Then he might have napped instead of taking yo... never mind!

Sully

 

[Bobby_M]

F that. Why did you let him get away with it? Did you pay him on the first visit too?