I am trying to get my 66 a/c working. Have replaced all lines, compressor, and accumilator. A shop changed it to R134a, and could not get the low side pressure below 60lbs, high side was at 260lbs. I am told low should be at 30 or even adjusted down to 20 with r134a. I have now rebuilt the stv valve with a new valve. Returned it to the shop and they still can not get it below 60lbs. Is there something they are missing or is 60lbs ok? The air out of the center vent is 50 on a hot day or maybe 45 on a cool day. Plaese Help!!
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Re: 66 vette A/C, Adjust STV valve??
Bill,
I have a similar problem. 1966 small block with C60, R134a and cant' get the temps below high 50's. Low side pressure at STV was 30 psi and today we tried lowering pressure at evap.. We backed the screw out all the way of the STV and evap pressure wouldn't drop below 28 psi Still cabin temps in the high 50's. We screwed STV screw all the way in to 45 psi to determine if STV was working.
In your case, I assume your shop put about 2 1/2 lbs. of R 134 in the system as it requires about 75% of the R12 capacity ( 3# 4 oz). Is it posssible you have too much R134a in your system?
In my case I have high side pressures of 325 to 350 psi. AC shop thinks I have a restriction some where. More fun.
Randy
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