Air Conditioning - A/C can't keep up during mid-day sun

I have recently run into a problem with my central A/C. I live in central Florida and during the night (when the sun isn't beating on the house) my A/C keeps up fine - I have the thermostat set to 76. During the day, however, my A/C cannot keep up. As soon as the sun comes out and starts hitting the house, the temp inside will slowly climb and top off at around 84 (the thermostat is still set to 76). Then, later in the day the temp will slowly come back down and hit 76 again. The a/c unit runs non-stop from about 9:30am until around 9:00pm (~ouch~)

One month ago, our A/C stopped working completely - ended up having to call for service and found out that there was a leak in the outside coil and we were out of freon. The tech fixed the leak. After the leak was fixed, he filled the system with some kind of nitrogen and put a gauge on it and left it for quite a while to verify that the leak was fixed. The line pressure remained the same during the whole test (which I verified) so I'm almost positive at this point that this isn't a leaking issue. I then watched him vacume the lines then fill with freon.

I've read soooo many posts in these forums and I've tried a LOT of stuff already on my own but I'm stuck and out of ideas...

I think the system is pretty old but I would really like to hold off on replacing major components since budget doesn't allow at this time - at least if I can get it running properly for one more year, that would be ideal.

The unit is an A/C w/ Heat Pump
The inside handler is a Goodman model A30-08 (not sure of age though). Outside unit is an InterCity model HPS030A2B1 (not sure of age)

Here's what I've done so far:
-Cleaned the inside evap coil (the coil wasn't very dirty - we change filters every 25-30 days (using Merv 8 3M filters).
-Cleaned the outside coil and straightened any bent coil fins.
-Removed the blower assembly and cleaned all of the fins.
-Crawled up in the attic and inspected duct work - patched a few places that were leaking air.
-Took the following temps at 5:00pm when house was 81 inside (90 outside):
-Before evap coil (at filter): 78
-After evap coil: 58
-Vents in ceiling range: 61-63
-Lineset: -big copper line is cold and wet, small line is warm and dry

The attic is well ventilated - there are continuous eve vents and continuous ridge vents. There are also two turbine vents... plus it worked before so I'm pretty sure that it has nothing to do with attic ventilation.

Here is a pic of the air handler and where the major components are:
http://boerst.com/diy/handler.jpg

Here's the outside unit:
http://boerst.com/diy/outsideunit.jpg

It's definitely pulling the humidity out of the air because it 'feels' cooler than outside but it's just not able to keep up...

I'm up for trying ANYTHING - does anyone have any suggestions?? Thanks in advance!!!

From the temp drop of 20 degrees, it's doing all it can do. Has it done fine in the past?

Do you close the blinds to keep the sun light out, and also no run high load item like the stove, dryer?

Where is the return vent at?

I hate to say it but something has changed. The what is the big question. Often it is a lifestyle change such as people coming & going more than before or the addition of appliances. Addition of people or pets can make a hefty difference. Leaving blinds open is a real biggie. Think about it & post back.
The temperature difference between supply & return looks good on the surface but more data would help.

Thanks for the replies guys!

We moved into the house in October and from October until about 1 month ago, everything worked fine. This might be a long shot but we did change the type of filters that we use... could that possibly make a difference? The previous owner stock-piled a few filters - we used those up and then started using these:

http://www.3m.com/us/home_leisure/filtrete/413_dust.html

I actually didn't think of this until now... do you think that trying a different filter would make a difference?

Sorry - I'll also add that once this problem started happening, we started shutting all of the curtains and shades in our house and it seems to help a little but it still gets up to 83 - even with the shades closed.

You betcha filters can make a difference. Presuming the old filters were the fiberglass type, the pleated ones can reduce the airflow by a good bit. If this is what was installed when the servicer charged your system & he/she simply charged by pressures or if the house was exceptionally hot, the refrigerant charge could be incorrect.

That is possible - it was REALLY hot when the tech came out. House inside temp was over 95 and super high humidity. I really don't how he charged the system - I checked the invoice and it only says "Freon charge", it doesn't say how many lbs he put in.
The old filters were fiberglass - I'm going right now to pick up a fiberglass filter to try for tomorrow. I'll post back with results tomorrow night. Thanks again!

How did it run previous to the leak? He may not have charged it completly.

Don't expect miracles overnight. It may take 2-3 days. The filter may not be the answer but it's cheap & easy to try.

How did it run previous to the leak? He may not have charged it completly.

It ran fine previous to the leak - it's very evident from our last electric bill. The thought crossed my mind about the freon not being filled properly but I'm getting a 20 degree drop over the coil so I thought that that would rule it out.

Don't expect miracles overnight. It may take 2-3 days. The filter may not be the answer but it's cheap & easy to try.

I just installed a filter similar to the old kind - it's just an el-cheapo but we'll see if it makes a difference - I'll give it a few days. Thanks.

Just some more info to add...

-The house is only 1080 sq feet.
-I just found some documentation stating that the outside unit was manufactured in '95 so the system can't be older than 11 years.

Where is the return vent at?

-Sorry, but is the 'return vent' the vent that sucks the air into the unit? If so, it's located directly below the air handler - in fact, if I remove the air filter from the return vent I can touch the evap coil.

Here's the sticker from the outside unit (may or may not be of use):

http://boerst.com/diy/outsidesticker.jpg

Ok, that might be the problem. If that is the only return vent and it's low it won't be able to pull the heat away from the ceiling, and also other rooms.

I take the supply vent (air blows out) are up in the ceiling?

Also, how big is this return grill? Take a pic of that as well.

Ok, that might be the problem. If that is the only return vent and it's low it won't be able to pull the heat away from the ceiling, and also other rooms.

I take the supply vent (air blows out) are up in the ceiling?

Also, how big is this return grill? Take a pic of that as well.

Yep, the supply vents are in the ceiling and there is one in every room of the house.

The return grill is 12" high x 24" long. It's about 2 inches from the ground. I'll take a picture of it when I get home (I'm at work right now).

Just curious, and since nobody's asked, how well insulated is the house?

1080 sq ft and a 2 1/2 ton AC should cut it there in FL. Most homes at 1900 sq ft there have just 3 tons. For sure dont go over a MERV 5 filter. Now 20o drop over the coil very very good But is the blower fan running at high speed ?? is it blowing at the right RPM?? Would you say that the same amount of air comes out of the register as in oct???? Or before the leak???
Then a heatpump can the A coil check valve leak freon back??? The 4 way valve ok??
It's definitely pulling the humidity out of the air because it 'feels' cooler than outside but it's just not able to keep up...
This could mean the blower is slow
With all the post here you sill have a lot of ifs ifs
ED;)

Well, I gave it a day with the fiberglass filter and I'm getting the same results - yesterday the house made it up to 80 (it was even overcast and rainy all day).

Also, how big is this return grill? Take a pic of that as well.

Here's a pic of the return vent located directly below the inside unit (the bottom vent near the floor). This is the only return vent in the whole house (again, house is 1080 sq ft):
http://boerst.com/diy/returnvent.jpg

Just curious, and since nobody's asked, how well insulated is the house?

The house is well insulated. I know that all of the exterior walls are insulated and so is the attic.

Would you say that the same amount of air comes out of the register as in oct???? Or before the leak???


It's REALLY hard to tell a difference - I guess I never had the need to pay attention to how much air blew out of the vents before... as far as I can tell, it's the same amount but I could be wrong. It would make sense that this could possibly be a problem with the blower. I already took it out and thoroughly cleaned each and every fin inside. I scraped quite a bit of dirt off of the fins but I honestly couldn't detect a performance improvement after the cleaning. It certainly doesn't sound any different when it's running and it is blowing quite a bit of air.

Then a heatpump can the A coil check valve leak freon back??? The 4 way valve ok??


Ed, I'm not really sure what you mean by this - Sounds like there is some kind of check valve that prevents freon from 'leaking' back. Is this valve inside of the outside unit? Is it something that I can test for functionallity? Is the 4 way valve part of the freon system? Is there any way that I can check this to see if it's malfunctioning?

-In my mind, since there is a 20 degree drop across the coil, it would seem that this is an issue with either the blower, leaky duct work or some kind of restriction of the airflow... am I right with this assumption?
I'm going to try crawling into the attic again tonight and check the duct work for leaks... it's the only other thing that I can think of aside from replacing the blower.
I just don't know what else to check?! This air conditioner is driving me NUTS!!
Any other suggestions/ideas?
Thanks again guys!

This is my own opinion, and I know there is not much you can do about the return.

The return is low and down on the floor where cold air is. It's puling the air off the floor.. Warm air rises... there is nothing up near the ceiling, and the heat builds up. It seems like it's a common thing in Fla with a single returns, where here in the midwest, return in most rooms either on the wall near the ceiling and few on the floor.

Do you have ceiling fans? Turn them on low, and that will stir up the air in the home.

That's a good suggestion with the fans. I actually don't have any ceiling fans in any of my rooms but I was kicking around the idea of putting a few in. That makes complete sense about the return being too low to the ground - if hot air rises, you would want the return to be near the top of the room to suck the warm air out... makes total sense.

I'm just stuck because I know that it was able to keep up fine before - the location of the returns and supplys never changed.

I know that it's been REALLY hot down here lately (hotter than one month ago) so maybe my A/C just isn't made to keep up with the extreme outside temps that we've been having lately. It's suppose to be 92 again here with 69% humidity...
It just feels like my A/C should be able to hold a temp throughout the day without having to constantly run... maybe I'm wrong.

Hot down there is if it get to 96o . We just had a week over 100o in the day and had one to 107o now thats hot. I have 1350 sq ft here 2 ton held it at 78 all the time and did shut off some in the day time.
As for as the cold air return being high or low. Up where Jay is it gets cold so the returns are all down on the floor. Mine here in Mo. now are also on the floor but the AC works fine. For a time here we tried cold air returns that you could go from a high to low for winter to summer. It just didnt make that much differents. Had 6 homes down in fl. west palm. 2 had a high return. The other 4 had low returns all worked fine after I did some work on the duct work most of it to small for the job. I ran one of the homes down there in the PC at shop. The same home sq ft up here in MO. takes a 1/2 ton more of AC than down there in FL. Now here in Mo it might run the AC 3 months but down there it has to run about 9 months.
Now if you are at Orlando or below A heatpump dont pay. Like you do have it now so yes use it. But if it goes out just get a AC unit and use the electric heat in the blower for the few days you need it. The higher cost for a heatpump dont pay you back.
Ed, I'm not really sure what you mean by this - Sounds like there is some kind of check valve that prevents freon from 'leaking' back. Is this valve inside of the outside unit? Is it something that I can test for functionallity? Is the 4 way valve part of the freon system? Is there any way that I can check this to see if it's malfunctioning?
Not much you can do here. You can feel the new drier he should have put in. Most are blue look like a little can.its in the small copper line going into the home. Feel if the temp is the same on both sides. Also the new drier should be one for a heat pump. Now think about it when you go to a heatpump the freon comes in to the coil in the big copper line. Its hot then and has to bypass the valve the let the freon in to the coil in AC. So that is where a check valve like a by pass can be. What gets me is that 20o drop you say you get over the coil right at the coil. That said to me the unit is working real real good??????
ED;) just my .02 cents