Low high side pressure in A/C
Thread Starter
Racer
Joined: Mar 2015
Posts: 415
Likes: 284
From: Indianapolis
Low high side pressure in A/C
So last summer I did some A/C work on the Vette. I was initially planning on finding a leak, as when I got the car the system was empty, but to my surprise when I pulled a vacuum on it it pulled to about 28 inHg and held there for a week. So I decided to charge the system and added some dye, figuring if there was a leak that only presented itself under pressure, the dye would help me find it. Got it charged and had ice cold A/C for the couple of months of driving I got before she got parked for the winter.
Fast forward to now. If I turn the A/C on, the compressor kicks on, the fans will kick on, but I've got nothing but warm air out of the vents. I hooked my gauges up today and with the engine at 2k rpm, on an about 80 degree day with 70% humidity, I've got roughly 30psi on the low side, and 95 on the high side (which is obviously way too low).
Any ideas as to why? I checked all over the car with a UV light and cannot find any indication of a leak.
Fast forward to now. If I turn the A/C on, the compressor kicks on, the fans will kick on, but I've got nothing but warm air out of the vents. I hooked my gauges up today and with the engine at 2k rpm, on an about 80 degree day with 70% humidity, I've got roughly 30psi on the low side, and 95 on the high side (which is obviously way too low).
Any ideas as to why? I checked all over the car with a UV light and cannot find any indication of a leak.
Pro
Joined: Dec 2014
Posts: 682
Likes: 275
From: Cincinnati Ohio
A few possibilities:
If you left your gage set connected for the week while it held vacuum, you could have a leak at one or both service ports when you removed the gage set,
You have a "phantom leak" that occurs in cold weather from one or more of the refrigerant system joints.
You have a leak in area you cannot see, such as within the evaporator module under dash. Have you used your UV light to look at the water dripping from the condensate drain? A leak might carry some dye with the water.
Can you pressurize your system with air? If so, you can use soap bubbles to check all the connections and see if the pressure decays over time.
If you left your gage set connected for the week while it held vacuum, you could have a leak at one or both service ports when you removed the gage set,
You have a "phantom leak" that occurs in cold weather from one or more of the refrigerant system joints.
You have a leak in area you cannot see, such as within the evaporator module under dash. Have you used your UV light to look at the water dripping from the condensate drain? A leak might carry some dye with the water.
Can you pressurize your system with air? If so, you can use soap bubbles to check all the connections and see if the pressure decays over time.
Safety Car
Joined: Mar 2017
Posts: 3,769
Likes: 940
From: Orlando Florida
On the side of compressed air testing, I added a paint gun desiccant to the down stream end of my air line to dry the air as much as possible — I am in central Florida, so my compressor also has an auto drain to try to keep up.
Thread Starter
Racer
Joined: Mar 2015
Posts: 415
Likes: 284
From: Indianapolis
A few possibilities:
If you left your gage set connected for the week while it held vacuum, you could have a leak at one or both service ports when you removed the gage set,
You have a "phantom leak" that occurs in cold weather from one or more of the refrigerant system joints.
You have a leak in area you cannot see, such as within the evaporator module under dash. Have you used your UV light to look at the water dripping from the condensate drain? A leak might carry some dye with the water.
Can you pressurize your system with air? If so, you can use soap bubbles to check all the connections and see if the pressure decays over time.
If you left your gage set connected for the week while it held vacuum, you could have a leak at one or both service ports when you removed the gage set,
You have a "phantom leak" that occurs in cold weather from one or more of the refrigerant system joints.
You have a leak in area you cannot see, such as within the evaporator module under dash. Have you used your UV light to look at the water dripping from the condensate drain? A leak might carry some dye with the water.
Can you pressurize your system with air? If so, you can use soap bubbles to check all the connections and see if the pressure decays over time.
The service ports was something I hadn't considered. I was debating on recovering what refrigerant is left and going ham on the system and replace every seal I can get my hands on. There is dye showing at the lo side service port, but my assumption was that was from when in injected the dye into the system.
Safety Car
Joined: Mar 2017
Posts: 3,769
Likes: 940
From: Orlando Florida
I thought that until I watched at full charge pressure, i.e. engine off and pressure equalized around 85 psi — then the low side Schrader bubbled.
Thread Starter
Racer
Joined: Mar 2015
Posts: 415
Likes: 284
From: Indianapolis
off to order new valve cores!
