a/c help

[flashback1962]

on my 67 riv. i have replaced the compressor, exspanion valve, and dryer. but still can;t get cooler then 57. does anyone have any ideas? also , i can;t seem to locate the pressure switch. theres a wire next to the dryer, but nothing to plug into. didn;t know if orig. dryer had a switch in it.

[troys67skylark]

What pressure's are the gauges, Was the system vacced long enough,Are the heater vent's closeing all the way. Cheers Troy

[flashback1962]

high side 200 low side 40 i sucked it down for 40 minites to 25 lbs the compressor and low side hose get cold enough to sweat. i blocked off heater hose. air doesn;t grt any cooler going down the road.

[troys67skylark]

I hope that was -25 psi/negitive psi. Also try adding 50gms at a time it may only take that much to be in the right range if useing R134A. I have never had to put a full factory charge in useing R134A and getting 3-4dgs at vent on low fan speed. Has your car got a TX valve or a POA valve. If it has a POA valve this can be by-passed and will work just as well. There is a post here about this subject. Good luck Troy

[flashback1962]

thanks, it was -25 i think i have a poa valve, if its a valve in low side hose, and small line from exspan. valve, and another small line going into air box , come off it .

[troys67skylark]

First try and add 50gms of gas and see what happen's. The POA valve is souposed to keep a constant perssure in the evaporator. If it play's up you get what you have. By-pass it and try again. If you are useing R134A put in 300grms less than factory for R12 run and add 50gms at a time untill it get's cold

[troys67skylark]

Does the low side gauge fluctuate 0_42/47psi or stay at 40psi.

[flashback1962]

it seems constant

[troys67skylark]

By-Pass By-Pass the POA and let the TX valav do it's job. Seams to me that the constant pressure on the gauge of 40psi is only 8dgs at that piont in the system witch will be about 12-15 dgs at the vent. By-Pass the POA and if your thermostst is working the low side gauge will fluctuate between -5 and 45psi maximum this will tell you that the thermostat is working if it stays around the 0 to 10 psi that will very good for that system. But i am sure that others will have plenty of input as well so it will pay to wait and read on Cheers Troy.