A/C pressures
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Cross-Country
Joined: Mar 2007
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A/C pressures
91 E150 4.9L V6 with dealer installed A/C
Converted from R12 to R134A several years ago. System has low pressure port at receiver drier but no high pressure port. Every year I add a can of R134A and system works fine for a year. I finally got a set of gauges to check system pressure. Does anyone know what the following pressures should be:
1) Pressure at low port with engine running and a/c off
2) Pressure at low port with engine running, a/c on and compressor engaged
3) Pressure at low port with engine running, a/c on at moment compressor cycles off.
Thanks
Converted from R12 to R134A several years ago. System has low pressure port at receiver drier but no high pressure port. Every year I add a can of R134A and system works fine for a year. I finally got a set of gauges to check system pressure. Does anyone know what the following pressures should be:
1) Pressure at low port with engine running and a/c off
2) Pressure at low port with engine running, a/c on and compressor engaged
3) Pressure at low port with engine running, a/c on at moment compressor cycles off.
Thanks
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
1) Pressure at low port with engine running and a/c off:
Ambiant Air Temp.(F) Low Side Pressure(psi)
50- 45
55- 51
60- 57
65- 64
70- 71
75- 78
80- 86
85- 95
90- 104
95- 114
2) Pressure at low port with engine running, a/c on and compressor engaged:
40-45
3) Pressure at low port with engine running, a/c on at moment compressor cycles off:
Should not happen but the Low side cutout switch should be set to open (stop the compressor) at 24 PSI and will let the compressor restart at 43.5 PSI.
Ambiant Air Temp.(F) Low Side Pressure(psi)
50- 45
55- 51
60- 57
65- 64
70- 71
75- 78
80- 86
85- 95
90- 104
95- 114
2) Pressure at low port with engine running, a/c on and compressor engaged:
40-45
3) Pressure at low port with engine running, a/c on at moment compressor cycles off:
Should not happen but the Low side cutout switch should be set to open (stop the compressor) at 24 PSI and will let the compressor restart at 43.5 PSI.
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