Automotive Air Conditioning Information Forum

1989 c1500 5.7 standard cab converted to r134a. Replaced accumulator, a/c high pressure switch on the r4 compressor, orifice tube, o rings, and valves. Truck lost all its refrigerant prior due to a leak. Added 2.5 oz pag 150 to accumulator, charged to 32oz.

ambient 86F, vent was cooling at 55F, low side pressure 37 psi, high side 195 psi.
Looking at the ac pressure chart it seems like its proper pressure readings, but for an ambient temperature thats 10F less.

Does the amount of oil affect the pressure in the system? I don't know how much oil was in the system prior so I just added 2.5 oz. Im just worried that the low pressures are caused by low oil since the system has the correct amount of refrigerant. Or could that indicate a weak compressor? My compressor doesn't seem to cycle at idle, only when driving and not much. Could this be caused by the cycling switch? It didn't indicate whether it was r134a or r12 type.

What are the pressures at 1500 rpm?

Not cycling is not necessarily bad.
As Tim said, need pressures at RPM he specified, with max fan, max cool, recirc, doors open (max load test). State vent temp and ambient temp. Assume u are using pro manifold gauge set with both hi and lo dials.

We can go from there