a/c issue
Thread Starter
TECH Apprentice
Joined: Jul 2012
Posts: 369
Likes: 4
a/c issue Any you guys really know a/c. my cars a/c is not cooling. Static pressure is 80-90. When I run it the low is 25psi and the high is 150-200, up and own with the needle. Used a UV dye and see nothing. The system is 134a. Any thoughts?
what year make model of car?
need to know what the outside temperature is when you are trying to use your ac.
if there are years on the ac system without being touched, it's likely it's lost a slight bit of r134a causing loss of cooling or minimal cooling. the fact that high side pressure goes up to around 175 psi and low side drops to below 30 psi indicates the compressor is functioning which is typically the biggest worry $$$.
assuming it's a gm vehicle with an orifice tube then it might simply be a dirty or clogged ac condenser in front of radiator, which is easy/free to clean yourself.
buy a digital temp thermometer from walmart for $10 and use that to accurately measure air temp in the vent in the cabin. simplest thing is to slowly charge the ac system and see if air temp measured by thermometer immediately drops, if so then its a slight undercharge. if you got a small 12 oz can of r134a you will not feel any weight change to get back to a proper charge you only need 1-3 ounces.
by up & down with the needle, that most likely means the low pressure is going below 25 psi which is tripping the low pressure cut off switch and the compressor is turning off for around 5 seconds, during that time hi/lo side pressure equalizes. high pressure needle will fall, low pressure needle rises. then compressor clutch engages (you'll hear it) and the process repeats.
need to know what the outside temperature is when you are trying to use your ac.
if there are years on the ac system without being touched, it's likely it's lost a slight bit of r134a causing loss of cooling or minimal cooling. the fact that high side pressure goes up to around 175 psi and low side drops to below 30 psi indicates the compressor is functioning which is typically the biggest worry $$$.
assuming it's a gm vehicle with an orifice tube then it might simply be a dirty or clogged ac condenser in front of radiator, which is easy/free to clean yourself.
buy a digital temp thermometer from walmart for $10 and use that to accurately measure air temp in the vent in the cabin. simplest thing is to slowly charge the ac system and see if air temp measured by thermometer immediately drops, if so then its a slight undercharge. if you got a small 12 oz can of r134a you will not feel any weight change to get back to a proper charge you only need 1-3 ounces.
by up & down with the needle, that most likely means the low pressure is going below 25 psi which is tripping the low pressure cut off switch and the compressor is turning off for around 5 seconds, during that time hi/lo side pressure equalizes. high pressure needle will fall, low pressure needle rises. then compressor clutch engages (you'll hear it) and the process repeats.
Thread Starter
TECH Apprentice
Joined: Jul 2012
Posts: 369
Likes: 4
a/c Its a 2006 gto. no orifice tube, uses an H-valve. V7 variable compressor.
80lbs static too high? dont think so. think thats pretty common.
Outside air temp was 80f
The high gauge (ONLY HIGH, LOW IS STEADY)takes a few seconds to go back and forth but its steady and consistent.
Compressor never cycles. I believe thats typical for variable compressors.
Some have said its a leak. I dont believe it with 80psi static and 200 psi running.
I believe its either the H valve and/or the valve in the compressor.
80lbs static too high? dont think so. think thats pretty common.
Outside air temp was 80f
The high gauge (ONLY HIGH, LOW IS STEADY)takes a few seconds to go back and forth but its steady and consistent.
Compressor never cycles. I believe thats typical for variable compressors.
Some have said its a leak. I dont believe it with 80psi static and 200 psi running.
I believe its either the H valve and/or the valve in the compressor.
if by H valve you mean Tx valve or thermostatic expansion valve,
then yeah it could be that. and if you have a tx valve then i would not add refrigerant until you first diagnose the tx valve, carelessly adding refrigerant would do more harm than good... or help a lot less.
here's a quick link for an explanation: http://www.rdac.com/resources/blog/c...xpansion-valve.
you can google "stuck tx valve" for various tries at fixing before outright replacement.
when the tx valve gets stuck closed, then your compressor works hard against a closed valve basically (it's not open enough to let refrigerant flow) and the high side will go high and the low side will go low. And i think the compressor will then suck the low side hard below 25 psi and trip the low pressure cut off switch, then the compressor will cycle off and on.
then yeah it could be that. and if you have a tx valve then i would not add refrigerant until you first diagnose the tx valve, carelessly adding refrigerant would do more harm than good... or help a lot less.
here's a quick link for an explanation: http://www.rdac.com/resources/blog/c...xpansion-valve.
you can google "stuck tx valve" for various tries at fixing before outright replacement.
when the tx valve gets stuck closed, then your compressor works hard against a closed valve basically (it's not open enough to let refrigerant flow) and the high side will go high and the low side will go low. And i think the compressor will then suck the low side hard below 25 psi and trip the low pressure cut off switch, then the compressor will cycle off and on.
