HELP!! HVAC Problem

[mlincoln]

My HVAC will not cool the home. Home warranty company doesn't know what the issue is. Home warranty tech says ac is good and working fine. He temped the the return air which measured 62 degrees the supply in the attic measured 65 to 68 and out of the vents he says it measured 72-79 depending upon room and duct length to that room.

Replaced evaporator coil about a year ago. Had an independent contractor inspect ac who believes it is compressor, compressor was leaking oil, and he believes valves bad he also checked ducts and said they were fine.

At a loss as to what problem truly is. Warranty company says they won't replace compressor and keeps saying its probably a duct problem but not sure. Any help advice or diagnosis would be appreciated!

[HayZee518]

oil just doesn't evaporate, look for spots or a coating on any piping in the area of the compressor. leaking oil will compromise your compressor and anything inside that moves and is lubricated. freon will leak out along with the oil. valves can be reed type or valves like in a car if the system is big enough. reed valves use a tempered spring steel sheet with a spring plate behind it. have your tech put gauges on the system and measure high side and low side pressures. a high gauge that oscillates indicates a leak.

[pushkins]

He temped the the return air which measured 62 degrees the supply in the attic measured 65 to 68 and out of the vents he says it measured 72-79 depending upon room and duct length to that room.

65-68 in the attic and 72-79 at the register ?????......that's a huge swing, these ducts in the attic are they insulated, there shouldn't be a swing of anywhere near 10 F from duct to register.

[jnaas2]

You say the return air measured 62 and that the supplys measured 72-79 are you sure your not stating this backwards. Normally when you are in the a/c mode the supply air measures 15 - 20 degrees colder then the return air ?. You didnt state if you have gas or electric I have seen a sequencer stick and the air conditioning and part of the heat operate at the same time

[mlincoln]

thanks

I did have it backwards. Thanks to all of your comments. The warranty place is going to replace the compressor as they found that that is the problem. Your comments help educate me as to what to ask them.

[HayZee518]

the refrigeration system in an air conditioner or a refrigerator is essentially the same. you are taking a hot atmosphere and through the freon are exchanging hot for cool.

[mlincoln]

Ok the problem still persists

AHHHHH! Ok New compressor installed and still the house isn't cooling. The Air from the AC is good and cool? However when it enters the duct to the supply in the home it heats up on average about 10-15 degrees. Everyone who has inspected the duct (3 different people so far) says that the insulation around the duct is good and that there are no kinks or holes in the ducts. They have commented however on how strange it is for the air to heat up so rapidly. When the air exits into the house through the vents its about 10-15 degrees higher. What can the problem be? Since we have been trouble shooting for the last two weeks we found out the AC unit is ok and the ducts have no visible wear nor is the insulation torn or worn. We are left with either clogged or dirty ducts or possibly the attic fans not working properly or possibly the need of new attic fans/vents to cool the attic? Any other suggestions or diagnosis regarding this problem? Your comments and or suggestions are greatly appreciated and welcomed.

[Java_Bob]

what is the supply air temp RIGHT at the air handler? 55 or so I hope

[mlincoln]

it read 60 degrees according to warranty tech

[pushkins]

If the air entering the ducts is 55 - 60 and while in the ducts in the attic it increases 10-15 degrees, then the problem obviously exists in the attic area.
Given that I doubt that anyone installed a heater inside the ductwork (lol....although that would make for a good hidden camera show) and conditioned air doesn't change 10-15 degrees that quickly up or down without a great deal of help I'd be looking at the attic temps. Ducting run in attics has always created a problem due to sometimes very hot attics with poor ventilation.
What is the temp. of your attic ?
At what temp. are your vents turning on ? (check the fans thermostat)
Is there a good flow of air coming out of all the vents serviced from the attic ?

[HayZee518]

mlincoln - please check out this site. since the a/c outlet temp is in the ballpark of what you are seeking the apparent problem is the ductwork. if you have adequate attic circulation for the radiant hot air inside, - gable vents, forced hot air removal, gravity soffit vents, then the ducts are the last that will absorb heat and warm up whatever is going through them.
hvac-duct-wrap-insulation

[mlincoln]

Yea according to the repair man it is over 100 degrees up in the attic (or as he described it, as hot as a firecracker). He suggested actually that we needed to ventilate the attic more to allow more air. He also suggested changing the thermostat. Could that really be the problem? I don't know if he check the thermostat on the fans but I am assuming he did. I've never experienced this problem before do you really think it could be as simple as that? I am going crazy because we haven't figured it out yet.

[mlincoln]

Thanks yea the warranty guy did describe it as hot as a firecracker up in the attic. Im not sure but ill assume he check the attic fans. Do you think that this could really be the problem with the temp. He did suggest adding more vents/fans in the attic to cool it down. He said the temp was over 100 degrees up there. Could this be where the heat is being gained? Does each attic fan have a thermostat? He did suggest replacing that as well.

[HayZee518]

the fans use a surface thermostat. some are fixed some are adjustable. gable vents are louvered slats of metal or wood mounted nearest to the peak in an attic. as heat rises normal convection currents should vent the heat out. air is drawn in via soffits at the eaves, then along the roof surface and then laterally out the gable vents.

[mlincoln]

So can it really heat up the air 10 to 15 degrees if proper circulation is not in the attic and it gets extremely hot?