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sprinkles08, ASE Certified Technician
Category: GMC
Satisfied Customers: 23130
Experience:  ASE Master and Advanced level certified. Factory trained with 17 years dealership experience
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2013 GMC yukon XL I replaced the AC condenser , I charged

Customer Question

2013 GMC yukon XL I replaced the AC condenser , I charged the system to 35 PSI low port put AC is not cooling enough, what is the correct pressure also I noticed that once that vapor is coming from the air vents ( it happedn only once so far)
Submitted: 2 years ago.
Category: GMC
Expert:  sprinkles08 replied 2 years ago.
Hello and welcome to JustAnswer!
The vapor you saw could have been from a leaking evaporator or it could have been from low a/c performance. When the system is cooling but not well it will cause a mist to come from the vents due to condensation on the evaporator.
Charging without a recovery machine or at least a scan is inaccurate, especially if there is an issue in the system adversely affecting pressures, but in most cases you can get close that way. Pressure depends on ambient temperature and humidity where the work is being done.
What was the temperature when charging the system?
How much refrigerant is in the system?
Customer: replied 2 years ago.
Temp was around 70. I don't how much charge inside. pressure is around 40 when compressor off. And around 55 when it is one
How to use the scanner while charging
Expert:  sprinkles08 replied 2 years ago.
It's far undercharged then. Static pressure in the system should be very close to ambient temperature.
You're seeing 55 PSI on the low side with the compressor running?
Customer: replied 2 years ago.
Yes I see 55 to 60 psi in the low side with the compressor running
Expert:  sprinkles08 replied 2 years ago.
You've got something going on in the system deeper than just being undercharged then.
The first thing that will need to be done is recover the system charge it to the proper level and then re evaluate it. The low and high sides are both going to need to be looked at to determine what is going on. You may have a restriction in the system, the cooling fan may not be working, or the compressor could be failing.
Customer: replied 2 years ago.
truck has only 50K miles and we replaced the condenser cause of accident so I don't think the compressor is failingwhat is the recommended PSI in both HI and low portsswhen the compressor is ON
Expert:  sprinkles08 replied 2 years ago.
Pressure is dependent on temperature but you aren't going to be able to charge based on pressure readings. 55 PSI on the low side is higher than it should ever be and that's what you're seeing with the system undercharged by almost 50%. If this started with replacing the condenser then there may be an issue in the replacement part.