73 A/C high pressure
Thread Starter
Heel & Toe
Joined: Jul 2016
Posts: 19
Likes: 0
From: Houston Texas
73 A/C high pressure
73 Stingray , I have replaced the compressor, VIR , an the condenser. when I charge it with the recommended amount of 134 I'm getting readings of close to 400 on the high side and 50 on the low side. Any ideas why ?
Melting Slicks
Joined: May 2002
Posts: 2,717
Likes: 121
From: Sulphur LA
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
did you pull a vacuum on the system prior to charging?
How are your radiator seals, are they in good shape and all in place?
Are you using the OEM radiator fan or electric, if the OEM is the fan shroud in place and in good shape.
All of the items mentioned if not correct will cause high head pressure.
Neal
How are your radiator seals, are they in good shape and all in place?
Are you using the OEM radiator fan or electric, if the OEM is the fan shroud in place and in good shape.
All of the items mentioned if not correct will cause high head pressure.
Neal
Burning Brakes
Joined: Oct 2001
Posts: 926
Likes: 200
From: TX
That pressure reading, high low and high high, would make me suspect the expansion valve in your vir is stuck open. What was the outside temp when you did your testing? What was the static pressure, i.e., compressor not running?
(I know you are using a new vir.) Other than being overcharged, thats all I can figure could be wrong.
Good luck!
VS
(I know you are using a new vir.) Other than being overcharged, thats all I can figure could be wrong.
Good luck!
VS
Drifting
Joined: Feb 2007
Posts: 1,498
Likes: 206
From: Pearland Texas
St. Jude Donor '09
I had same issue but with electric fans. I had to install a Trinary switch to make fans come on with AC compressor and pull air thru condenser right away.... But that was for a Electric fan set up. If you have a mechanical fan and clutch, you might want to make sure your clutch is good.
Thread Starter
Heel & Toe
Joined: Jul 2016
Posts: 19
Likes: 0
From: Houston Texas
Vir
That pressure reading, high low and high high, would make me suspect the expansion valve in your vir is stuck open. What was the outside temp when you did your testing? What was the static pressure, i.e., compressor not running?
(I know you are using a new vir.) Other than being overcharged, thats all I can figure could be wrong.
Good luck!
VS
(I know you are using a new vir.) Other than being overcharged, thats all I can figure could be wrong.
Good luck!
VS
Melting Slicks
Joined: May 2002
Posts: 2,717
Likes: 121
From: Sulphur LA
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
Typically if the expansion valve is stuck open you will see a high suction pressure and a low head pressure. Being there was a large difference in pressures I don't think it is a stuck expansion valve.
How much 134a did you put into the system?
Did you pull a vacuum prior to charging?
Is it cooling any at all?
Neal
How much 134a did you put into the system?
Did you pull a vacuum prior to charging?
Is it cooling any at all?
Neal
Last edited by chevymans 77; Feb 20, 2018 at 10:28 PM.
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Burning Brakes
Joined: Oct 2001
Posts: 926
Likes: 200
From: TX
As chevyman points out, air in the system could cause your problem.
Don't know how to test the vir x valve but if it is stuck open you should at least get some cooling. I bet its something else since its new but stranger things have happened. Part of the fun?
Also, too much oil can cause your high low and high high reading.
Was that pressure reading at 2000 rpm?
Keep at it. I rebuilt my 69 factory a/c (stayed with R12) and found it very cool to have A/C this summer in Texas.
