A/C Blowing Cold Air, Not Cooling House

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  #1  
Old 06-28-12, 01:56 PM
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A/C Blowing Cold Air, Not Cooling House

Wow, 241 users in this forum...must be summer.

Anyway, did a search, found some helpful info., didn't work.

So here it is. It feels like I am running my a/c (Amana Distinctions) with the windows open. Can't get the house cooler than 78 in high heat (90+) or 75 in low heat (mid 70's). At first we thought maybe the filter was clogged due to all the construction we've been doing (hadn't changed it for about 60 days) and the evap coils were icing. It was pretty dirty, but changing it didn't help. I had an HVAC guy come out and check the temps at various points in the system...everything checked out normal. Air coming out of registers gets the floor around them ice cold, but like I said, it feels like I have the windows open or there is a heat source somewhere. Shutting doors will get the smaller rooms significantly cooler than the rest of the house (halls and living areas that can't be blocked off) but that is annoying and something I have never really experienced.

Before everyone jumps on me about insulation, I have ample attic insulation and brand new windows that are sealed, foamed, and caulked properly. I have oil heat and was able to heat the house all winter (October through March as necessary) with less than a tank of oil (less than $150 a month on average for that six month period...pretty awesome). This is with no supplemental wood heat or without running the heat pump. So as easy as it was to heat the house, I don't know why it is so difficult to cool.

Ideas?
 
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Old 06-28-12, 04:52 PM
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How big is the house ? what is the AC size ? what is the temperatures of the cold register air and return register air ? Is air flow strong ?
 
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Old 06-29-12, 05:02 AM
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2 ton, 13 seer unit. Installed in 2009. House is an 1150 sq. ft. ranch. There are 3 bedrooms in a row on one end. Each end bedroom has 2 supply vregisters and 1 return. The bedroom in the middle has 1 supply and 1 return. The other side of the house is split down the middle, kitchen on one side and living room on the other. There are returns in the shared wall, one for each room. Plus each room has 2 supply registers. Finally, there is a supply register in the bathroom.

Did some readings last night. Supply air is 59. Return air is 78. Ambient temps in the house at the time were 80 on the main floor, 69 in the basement (if that makes any difference).

Air flow feels strong.

Are there any other filters that need to be changed/serviced? The house was a foreclosure when I bought it (not sure that the filter had been changed since install; it was absolutely filthy) and had sat vacant for a few years. For awile, I was changing the filter every few weeks just because there was so much dust in the system. After awhile, I got the ducts cleaned out and normalized. But suffice to say if there are other filters/parts that could be affected by dirty ducts, they likely are.

A few other things I believe it could be (hoping someone could verify and then direct me how to address them).

Dirty or leaky return air system
Dirty condenser coils
Dirty evap coils
Leaky supply lines

Of course, there are no visible leaks, so it would just be a matter of me sealing/taping all connections.

Should I try cleaning coils?

I'm not asking for a lot. Even with a properly functioning system I don't often set the t-stat lower than 76. But even when it was cooler out, this system could barely acheive that and had to run constantly to do so. I can't afford a $400 electric bill as I am currently unemployed (anybody in Western PA hiring?)

Thanks for any and all help!
 
  #4  
Old 06-29-12, 07:38 AM
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With 19 degrees split and strong air flow and also good isulation, I can't think of any reason the house does not cool down fast. If you have leaky duct, dirty coil, etc. you won't even get 19 split or strong air flow. Just one more thing to make sure, when you say air flow is 'strong', how strong ? can you feel it 8 feet away from the register? or after you turn AC on, do you immediately feel cool air at the other end of the room ? To be sure, call a tech to measure the air flow to see if it is normal, should be around 400cf/m. If the air flow is normal, then insulation is the next thing to check, I know you said you have good insulation, but what else can be (this is simply physics) ?? Get a temperature gun(around $50 at Amazon) may help you find the spots(windiows or walls) that do not have good insulation.
 
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Old 06-29-12, 11:08 PM
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Air filters don't do a good job on fine plaster dust so the coil could be plugged as you said.

Running an a/c when doing dusty renovations is never a good idea.

A 2 ton unit shouldn't have any trouble keeping a <1200 sq ft house cool if it's running at capacity.
 
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Old 06-30-12, 12:57 PM
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Red face

Just one more thing to make sure, when you say air flow is 'strong', how strong ? can you feel it 8 feet away from the register? or after you turn AC on, do you immediately feel cool air at the other end of the room ?
No to both. I guess maybe the flow isn't as strong as I had thought if these are good rough ways to measure it. Lets say maybe due to renovations my coil is plugged....what is the best way to go about fixing that?

Thanks for the help, I really appreciate it.
 
  #7  
Old 06-30-12, 03:07 PM
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Open the air handler panel, use soft brush and coil cleaner. if it is dirty (you can see that once you open the panel, check air input side), better call a prefessional to clean it, it is not a easy job.
 
  #8  
Old 07-04-12, 05:09 PM
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I'm having a similar issue and the finger is pointing towards renovation as well. AC unit was doing a fine job at the beginning of the week. Now, seems like I have no pressure in the system and no cool air. We have had contractors in the house since Monday and when I to the area where they were working, the return vent was wide open.

Unfortunately, there is no panel where the coil would be. It looks like everything was taped and glued shut.
 
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