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Debert · Jun 27, 2008, 05:25 AM

I recently bought a Trane system (compressor & blower). The system max out at about 80 degrees. It doesn't go below that temperature in the days. It runs all day, especially in the afternoons. I had a 9 SEER system and this is a 1/2 ton higher and 15 SEER unit, and it work as poor as the 9 SEER system. This new system uses more energy than the old system.

The company sent technicians to evaluate the system and the say it working OK. No one seems to have an answer to the problem why the unit doesn't cool below 79 or 80 degrees. The outside temperature in South Florida is between mid 80's to low 90's degree, but regardless the system can't cool the house below 80 degrees. Can someone tell me what's going on?:confused:

rsain2004 · Jun 27, 2008, 06:11 AM

The way I was taught, is the best one can hope for is a 20 degree drop across the evaporator of an A.C. Is the condenser exposed to direct sunlight? Measure the temp of the intake air, and the discharge air at the evaporator.

wmproop · Jun 27, 2008, 09:51 AM

Could be overcharged,, if undercharged it would probably freeze up., also are they sure its big enough,, are there enough returns ? Did they replace the thermostat ? Is the tstat located in the right place?, do you have enough insulation? many things to look at that could be the cause

poppyla0011 · Jun 27, 2008, 10:06 AM

Check to see if the unit has a filter, change filter.

Check to see that all ducts could be insulated, and check for gaps.

Check to see that the unit is the correct size for your home.

Check to see that the house is properly sealed against the outdoors.

Debert · Jun 27, 2008, 09:14 PM

Originally Posted by rsain2004

The way I was taught, is the best one can hope for is a 20 degree drop across the evaporator of an A.C. Is the condenser exposed to direct sunlight? Measure the temp of the intake air, and the discharge air at the evaporator.

Thanks for responding. I'm quite ignorant about ac operation, but the difference between the air going into the air handler and the air coming out of the nearest vent is approx. 16 degrees. When the temperature outside is between 86 degrees and 93 degrees the thermostat does not move from 79 degree and the unit does not cycle off. The house was checked for leaks by our local utility company. They used a blower door test. They concluded that there were no leaks and that the insulation was more than adequate. The system that the house came with worked well. We did not have this kind of problem and the old one was a 3 ton. This new system is a 3.5 ton. This new system uses 410A refrigerant. My old system used R22.

Debert · Jun 27, 2008, 09:20 PM

Originally Posted by wmproop

could be overcharged,,,,,,,,,,,,if undercharged it would probably freeze up.,,,,also are they sure its big enough,?,,,,,are there enough returns ? did they replace the thermostat ? is the tstat located in the right place?,,,,do you have enough insulation? ,many things to look at that could be the cause

Thanks for responding. I'm quite ignorant about ac operation, but the difference between the air going into the air handler and the air coming out of the nearest vent is approx. 16 degrees. When the temperature outside is between 86 degrees and 93 degrees the thermostat does not move from 79 degree and the unit does not cycle off. The house was checked for leaks by our local utility company. They used a blower door test. They concluded that there were no leaks and that the insulation was more than adequate. The system that the house came with worked well. We did not have this kind of problem and the old one was a 3 ton. This new system is a 3.5 ton. This new system uses 410A refrigerant. My old system used R22. The thermostat was changed from one the old type to a digital one. How can you tell where the right place is for a thermostat?

wmproop · Jun 27, 2008, 09:23 PM

How much time are you giving it? I`ve seen units on a very hot day,and especially when there has been a long down time take 7-8 hours to pull all the heat out ,we talking hot furniture,walls carpet,sometime it can take a while, this is why I try to explain to people to not turn their a/c `s completely off when away,, takes a long while for the a/c to pull all the heat out,cool it and blow it back into the house

Debert · Jun 27, 2008, 09:25 PM

Originally Posted by poppyla0011

Check to see if the unit has a filter, change filter.

Check to see that all ducts could be insulated, and check for gaps.

Check to see that the unit is the correct size for your home.

Check to see that the house is properly sealed against the outdoors.

Thanks for responding. I'm quite ignorant about ac operation, but the difference between the air going into the air handler and the air coming out of the nearest vent is approx. 16 degrees. When the temperature outside is between 86 degrees and 93 degrees the thermostat does not move from 79 degree and the unit does not cycle off. The house was checked for leaks by our local utility company. They used a blower door test. They concluded that there were no leaks and that the insulation was more than adequate. The system that the house came with worked well. We did not have this kind of problem and the old one was a 3 ton. This new system is a 3.5 ton. This new system uses 410A refrigerant. My old system used R22. Filter is new. It came with the system.

Debert · Jun 27, 2008, 09:33 PM

Originally Posted by wmproop

how much time are you giving it? I`ve seen units on a very hot day,and especially when there has been a long down time take 7-8 hours to pull all the heat out ,we talking hot furniture,walls carpet,sometime it can take a while,,this is why I try to explain to people to not turn their a/c `s completely off when away,,,takes a long while for the a/c to pull all the heat out,cool it and blow it back into the house

We keep the unit running at 82 degrees when we are not home. When we are home, if it goes to 78 in the morning, by the afternoon it goes back to 79/80 and cycles on until night. At night it works fine -thermostat maintains 78 and unit cycles on and off.

wmproop · Jun 27, 2008, 09:43 PM

Sounds like a pretty warm setting to me ,but what ever make you comfy,, not knowing where you live and what the average outside temperature is,, but most good working a/c should get your house 15 to 20 degrees cooler than it is outside,, around here we keep the temperature set at around 72-73 degrees

rsain2004 · Jun 27, 2008, 10:27 PM

A 16 degree drop across the evap isn't so bad... Do you have an outside door that is constantly used? Perhaps the fresh air intake of the air handler should be closed completely to see if things change...

Missouri Bound · Jul 1, 2008, 08:26 PM

What is the temperature of the supply air, and the temperature of the return air? Is the return air register located high near the ceiling or near an outside wall where the temperature is higher than room temperature? Have you closed off some registers restricting the cooling ability of the unit? Filters clean, return grill not blocked? I have about a 15 degree differential between return and supply air and can easily keep my home 73 degrees when it's 104 in the heat of the day.