A/C pressure with 134A

[marcus_sho]

What should the line pressures be for the A/C when it is converted to 134A? Or at least what should it be with R-12?
I had my system converted to 134A and over the winter a line was cut from the power steering pump, I replaced the line and am refilling the system and cannot find the recomended pressure for the system.

thanks

<small>[ June 28, 2002, 12:23 PM: Message edited by: marcus_sho ]</small>

 

[Rob94]

I have no idea about the R-12, but with the 134-a, the operating pressure on the low side is 25 psi.

 

[projectSHO89]

Low side pressures will be the same as R-12 as it is controlled by the pressure cycling switch.

The switch opens at 25 psi decreasing and closes at 45 PSI increasing.

High side pressures are typically higher on a 134 conversion than with the original R-12, assuming you are using the original R-12 components. Actual pressure readings will vary with ambient temperature.

Steve

 

[clintonk]

FWIW, the clutch cycling pressure switch is adjustable. Just turn the screw between the terminals a quarter turn or so and re-check the low-side pressure. To help compensate for 134A's lesser performance, I set my cars to 19-20 psi to get the evaporator a little colder. Never had a problem with the evaporator freezing up.

Clinton Knight
'90 White 182K
'95 Green 53K