Another AC issue - Low side at 125psi
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Pro
Joined: Oct 2004
Posts: 628
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Another AC issue - Low side at 125psi
I am getting code 09 (low Freon) on my '92 Lt-1 Vert. My AC system was converted to R134a by a dealer about 2 years ago.
I went to NAPA and bought some R134a plus a pressure guage. However, when I took the initial pressure reading on the low side (scrader valve at the accumulator) it is reading 125psi!
I have searched on this forum and I think I saw that without the compressor running both sides can equalize.. is it simply a case of forcing the compressor to run by jumpering the low pressure switch? Or can I just put a can of 134a into the low side and hope that it kicks the compressor into life?
Many thanks,
Andy.
I went to NAPA and bought some R134a plus a pressure guage. However, when I took the initial pressure reading on the low side (scrader valve at the accumulator) it is reading 125psi!
I have searched on this forum and I think I saw that without the compressor running both sides can equalize.. is it simply a case of forcing the compressor to run by jumpering the low pressure switch? Or can I just put a can of 134a into the low side and hope that it kicks the compressor into life?
Many thanks,
Andy.
Le Mans Master
Joined: Jul 2005
Posts: 5,193
Likes: 16
Yes the sides have equalized. You have to get the compressor to turn on in order to lower the pressure enough to get the freon in. See if you can jump out the low pressure switch. The lowside pressure has to be lower than the freon can pressure in order to induce flow. Lowside pres. should be around 70 psi, depending on outside air temp.
Drifting
Joined: Mar 2002
Posts: 1,251
Likes: 2
From: Thomson Georgia
70 is high. At 1500 rpm, look for 35-50 psi, with the fan on high speed and max air setting, all doors, windows closed.
It the compressor cycles quickly, it is low on a charge. Don't just dump the whole can in there, you may overcharge it, that causes other problems.
If you can stick a thermometet in the center vent. When the charge is close, R134 will usually be between 46d-56d F, R12 between 40d-46d F.
70 psi will give you around 56d-60d F+ and 320+ psi head. That'll kick the over pressure switch.
Ambient air temp has a lot to do with it.
johnny
It the compressor cycles quickly, it is low on a charge. Don't just dump the whole can in there, you may overcharge it, that causes other problems.
If you can stick a thermometet in the center vent. When the charge is close, R134 will usually be between 46d-56d F, R12 between 40d-46d F.
70 psi will give you around 56d-60d F+ and 320+ psi head. That'll kick the over pressure switch.
Ambient air temp has a lot to do with it.
johnny
