New A/C problem (may be long) (1 Viewer)

[Keith_R]

Hey guys, don't know if anyone has any experience with air conditioners here but our new A/C is really wacky and was wondering if anyone had any opinions or advice. Here's the story, around mid March our old A/C unit's compressor broke and we decided to get a new A/C unit which was the same brand as the one before, a Carrier. The new unit is supposed to be more efficent with HEPA filtration etc. it even has one of these new digital thermostat things which are supposed to be more accurate. Now moving into Summer my state, Florida has had it's warmest days yet and our air conditioner has started wigging out (at least to us). A good example of this was Last friday when the air was set to 79 degrees, our typical temperature and the thermostat showed 84 in the house . We immediatly called our installer and he came over, he checked and everything was fine with his unit, one of his workers bumped the air down to 72 or 73 and it worked fine but it seemed to run for 2 hrs straight without hardly shutting off or not shutting off at all. The following day the same thing happened. Once again the installer came out and added more insulation behind the thermostat, same stuff happened worked fine but hardly shut off except at night it continued normal cycle no problems. Sunday it did the thing where the thermostat kept going up and up despite the set temp and the unit would rarely shut off, by now the installer agreed to install a new thermostat and see if it worked so we were waiting until Monday to do that. Yesterday rolled around and it repeated the events of Saturday and Sunday until the installer came over and installed our new thermostat. Everything worked fine last night and than today when I got home it started acting up again going to 82 when it was set on 79. We kicked it down to 77 but it seemed to take an hour to even go down a degree. The concern here is that possibly the unit we have may be unefficent for our house since this problem seems to occur in the heat of our florida days. Our neighbors have the same unit only slightly bigger and claim no problems with theirs, they usually keep their termostat set around 75 or so and never change it. The installer who did our neighbors's did ours and is their friend. Him and his 2 workers have checked the unit and claim it is running fine. He is willing to put the heavier version of our unit in for $350 but what extra good will 1/2 a ton do?! given what I describe do you think the unit is inefficent for our 1100 SQ ft house or are we just going crazy? all materail the installer has on our unit claims it can work fine for our SQ footage but you never know. Thanks.

 

[Jerry Klawiter]

Do you now have a 2ton?
That extra 1/2ton could make a huge difference.
This is all dependent on the home, insulation, windows,
You are in the sun-belt region with a high moisture levels,
do you have any midday shade over your home?
Here in Minnesota we do get very hot & humid, But most homes here are well insulated as are the windows, this tends to make it much easier on the A/C.
I have a 2 ton ten+ year old unit that cools our 3000sq,ft.
home without problems. Yes it can take several hours to recover and drop the temp five degrees when first turned on, removing heat & moisture takes some time, But after that the unit should only need to cycle, The frequency again is all dependent on the above.
-Jerry

 

[Keith_R]

Do you now have a 2ton?

Yes we do have a 2 ton. The machine itself is a heat pump and the house is well insulated, the installer even said that. Thre installer is set to come out Thursday with his workers and do a thorough check but the more and more we think about it this thorough check will probably do nothing because the A/C may not be efficent for this house. The problem as was said only seems to occur at the hottest point in the day which tells me at a certain temp the A/C can not work effectively. Why would the extra 1/2 ton make a difference that big? extra parts? thanks.

 

[Jerry Klawiter]

The sheer added capacity can make a huge difference.
And can pay for it's extra cost in short order, as it will recover faster, remove moisture faster, cycle shorter.
I just have a hard time understanding why a 2ton can not keep up with your 1100 SQ ft house?
What about the compressor? anything around it?
Are the fins clear of the spring bloom?
One year our unit was really working hard it was about 102 and the dew-point was around 75-80.
The air coming out of the registers was not as cool as normal, I went outside to look and the fins seemed clear.
But that air coming out was real hot.
Just for the heck of it I took out the garden hose and spray some cool water on the unit, WOW did that make a huge difference in the cooling!
Now I know when our unit dies, it will be replaced with a 2.5 ton, in the meantime when we have those very hot days and the unit is laboring, the sprinkler comes out just to mist the compressor and water the nearby greenery.
-Jerry

 

[Jerry Klawiter]

Why would the extra 1/2 ton make a difference that big? extra parts?

Usually the compressor is larger, more sq inches of heat dissipation area in the surrounding housing, with a larger volume of fluid.
Remember we are removing heat from within the home and not cooling the air.
-Jerry

 

[DaveMcS]

Do not OVERSIZE the unit by too much though..bigger is not always better when it comes to air conditioning. The air will be cooled off before proper dehumidifying can occur. MANY homes with oversized condensors are found to have problems associated with dampness (mold, mildew, etc) because the air in the house is not properly "conditioned.

Just an FYI

 

[Chris Baucom]

Also, check your condensate drain. If it has a PVC pipe that runs away from the unit, they sometimes can get pushed into the soil and become clogged. If that happens water can backup into the system, making it much less efficient.

Also, I'm sure this has been checked, but is your thermostat near a return? Code should mandate that it is, but just checking.

 

[BrettB]

I assume the installer has checked for leaks. It took 2 years for our installer to figure out we had a bad A-coil.

 

[Keith_R]

Update, It once again had the same problem here around 4:00 or so. The air was set at 77 and the temp within the house rose to 81 despite the fact that the air was running. We had to finally kick it down to 75 for it to cool the house down.The thing is I don't believe the thing has shut down once since 4:00 today and has been running continuosly w/o going in cycles which that in itself is pretty wierd. The house has cooled down now nicely but once again it is not in the heat of the day. The installer will be out tommorow to do a thorough check-up but I really don't see how anything could be wrong since the A/C is only about 3 months old and never had a problem like this before. If everything is fine with it what should we do than? it would seem like we've run out of options other than to pay $350 to put the extra 1/2 ton unit inside which we really don't have the money to do nor should we have to do. The unit was sold to us on the basis that it would work for our SQ footage which is what the manuals for the installer all say. It seems as though the A/C cannot handle our Florida heat, whereas our old Carrier unit handled it fine.

Also, check your condensate drain. If it has a PVC pipe that runs away from the unit, they sometimes can get pushed into the soil and become clogged. If that happens water can backup into the system, making it much less efficient.

Also, I'm sure this has been checked, but is your thermostat near a return? Code should mandate that it is, but just checking.

I'm pretty sure he has checked for leaks but I'll mention it to him. As far as the thermostat I don't know if it is located next to a return but it is where the old one was and the old one worked fine for where it is. The installer also said the thermostat was located in a perfect place as well. Thanks!

 

[Jerry Klawiter]

Anytime from 3pm-5pm is the hottest part of the day.
And it will not start to cycle until it has met the thermostat requirements. Set thermostat @ 78 and it should run continuously until the inside temp reaches 78.
Something does not seem right.
What is the temp rise or in this case drop?
Take a measurement of the air temp coming out of a nearby register and compare that to the inside/outside house air temp.
To me it sounds as if the compressor is giving out and
the thermostat keeps calling for cooling so the blower keeps blowing air, but yet the compressor is not circulating.
Check the line where in enters into the blower next to the H or A coil the next time this happens. See if it's cold?
Maybe moisture in the system?
-Jerry

 

[Eric Kahn]

You have the classic symptoms of an undersized unit
2 tons for an 1100 sq ft house in fl just is not going to be enough, unless you have like R 40 insulation and never open the doors and have no air leaks
the other problem may also be not enough air movement over the a-coil,

if you want to check for yourself, get a probe thermometer and stick into the duct over the A-coil while the unit is running in the after noon, the output air should be at least 20 degrees cooler than the room temp as displayed on the thermostat

one other thing you can do is to shade the condensing unit if it is in the sun in the afternoon, it will make a big difference but I think you need a bigger unit

2 tons is 24,000 BTU's an hour of cooling, 1 ton of cooling being 12,000 BTU's an hour

 

[Keith_R]

Update: The installer came over today as planned and the problem is fixable! It turns out the compressor is broken and that all that needs to be done is install a new one. Seeing as though the A/C is less than 3 months old Carrier has agreed to replacing it and will pay the installer for the work that has to be done so we will lose no money from our pockets for this. The installer in the meantime has rigged it so the current compressor works and our house is feeling the coolest it has in a week. The new compressor should be installed mext week.

 

[Chris Baucom]

That's great. Keep us up to date once the swap out occurs.

 

[Jerry Klawiter]

The installer in the meantime has rigged it so the current compressor works and our house is feeling the coolest it has in a week.

I hope you don't wake up tomorrow a frozen Popsicle.
I felt that compressor was suspect.
Good news.
Check back in after the work has been complete.