Air Conditioning - Evaporator Coil/TVX Problem...Maybe
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Treble
05-05-06, 10:46 PM
Rheem Classic 3 ton unit in a 1 story 1100 sq ft. home with 6 vents.
2 years ago I had an A/C check up (routine) and asked the technician if the air flow could be reduced since it is very strong out of the two vents right above the plenum. He suggested I install a filter in the return vent and also installed foam dampers in the two referenced vents. Air flow was reduced and no problems. Just had a new A/C check up (routine) and I apparently have a problem.
He said the pressure was low (50 PSI from the vapor line port at 80-85 degrees ambient) but the unit would not take more R-22. He felt the pressure was low since the unit was not getting enough air flow due to the dampers and return filter so we took them out. Pressure increased to 60-62 PSI but still would not take R-22. He said I need a new coil since the system wont take more R-22. He stated 70-75 PSI as the needed pressure. Warrantied part but big $$ for labor.
Sytem has always cooled fine so I asked a friend of a friend A/C technician who was nice enough to give me phone advice. He said evrything sounds fine and don't replace the coil because the TVX was doing the job of not allowing more R-22 in.
If needed, I plan on replacing the part myself and having the recover and recharge done by an AC technician. But before I do this, I could use some other opinions due to the conflicting diagnosis. The Rheem chart states 60-62 PSI is good at that temp.
Also, if there really is a problem, wouldn't the TVX be the part to replace and not the whole coil
Thanks in advance for your help.
T.
2 years ago I had an A/C check up (routine) and asked the technician if the air flow could be reduced since it is very strong out of the two vents right above the plenum. He suggested I install a filter in the return vent and also installed foam dampers in the two referenced vents. Air flow was reduced and no problems. Just had a new A/C check up (routine) and I apparently have a problem.
He said the pressure was low (50 PSI from the vapor line port at 80-85 degrees ambient) but the unit would not take more R-22. He felt the pressure was low since the unit was not getting enough air flow due to the dampers and return filter so we took them out. Pressure increased to 60-62 PSI but still would not take R-22. He said I need a new coil since the system wont take more R-22. He stated 70-75 PSI as the needed pressure. Warrantied part but big $$ for labor.
Sytem has always cooled fine so I asked a friend of a friend A/C technician who was nice enough to give me phone advice. He said evrything sounds fine and don't replace the coil because the TVX was doing the job of not allowing more R-22 in.
If needed, I plan on replacing the part myself and having the recover and recharge done by an AC technician. But before I do this, I could use some other opinions due to the conflicting diagnosis. The Rheem chart states 60-62 PSI is good at that temp.
Also, if there really is a problem, wouldn't the TVX be the part to replace and not the whole coil
Thanks in advance for your help.
T.
mattison
05-06-06, 07:31 AM
1st off. How old is your system ??
Are you sure it has a TXV and not a piston ?
By the time you pay for the recovery and recharge you could just pay them to do the whole job and get a warranty.
Did the "tech" mention what the head pressure was?
Are you sure it has a TXV and not a piston ?
By the time you pay for the recovery and recharge you could just pay them to do the whole job and get a warranty.
Did the "tech" mention what the head pressure was?
tinner73
05-06-06, 09:23 AM
3 ton unit for 1100sq'...where to you live? on the sun?
i'd bet your system is WAAAAY oversized. 3 tons of a/c will require 1200 cfm. you state you have 6 outlets. what size outlets are they...i hope they are at least 8" each. what size is your supply trunkline? what size is your return? i think you have airflow issues.
i'd bet your system is WAAAAY oversized. 3 tons of a/c will require 1200 cfm. you state you have 6 outlets. what size outlets are they...i hope they are at least 8" each. what size is your supply trunkline? what size is your return? i think you have airflow issues.
mattison
05-06-06, 10:50 AM
3 ton unit for 1100sq'...where to you live? on the sun?
:D I didn't even catch that. Does look slightly oversized.
:D I didn't even catch that. Does look slightly oversized.
Treble
05-06-06, 11:34 AM
Thanks for your replies. I'll start by answering a few of your questions.
The unit is 4 years old and does have a TXV not a piston or cap tube. I live pretty close to the sun here in south Florida. Vents are 8" and 10". We thought the unit was oversized but 6 vents x ~200 CFM per vent is 1200 CFM.
The technician did not check the head pressure that I recall. The liquid line looks like 5/16" and the vapor line like7/8".
I guess the main question woulkd be is could the TXV be preventing more charging with the system being properly charged and is this normal or does it require the repair.
Mattison may be correct on the $$ issue even if I do the replacement myself, but I still need to figure out if the replacement is needed. $500 is alot to pay for a product still under warranty!
Thanks again
The unit is 4 years old and does have a TXV not a piston or cap tube. I live pretty close to the sun here in south Florida. Vents are 8" and 10". We thought the unit was oversized but 6 vents x ~200 CFM per vent is 1200 CFM.
The technician did not check the head pressure that I recall. The liquid line looks like 5/16" and the vapor line like7/8".
I guess the main question woulkd be is could the TXV be preventing more charging with the system being properly charged and is this normal or does it require the repair.
Mattison may be correct on the $$ issue even if I do the replacement myself, but I still need to figure out if the replacement is needed. $500 is alot to pay for a product still under warranty!
Thanks again
theapprentice
05-10-06, 12:03 PM
The first servicman didn't know what he was talking about. Either that or he is a crook. The air-flow could definitely be your problem. It is now probably overcharged due to the first guy trying to force refrigerant in the unit. You need a qualified tech to troubleshoot your unit. Ask a friend or neighbor if they know someone competent.