1976 Firebird A/C HELP!

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camaroguy
Posts: 5
Joined: Wed Dec 28, 2016 1:22 pm

1976 Firebird A/C HELP!

Postby camaroguy » Tue May 29, 2018 6:58 pm

Guys and gals. I have a all original 1986 firebird Formula 400. I did replace the compressor, all a/c lines and o-rings. I flushed the system and vacuumed for a few hours. It held 28” of vacuum for 5 hours. I charged it with R-12 it will cool to 58 degrees then starts to warm up. The high side hose is hot and the low side is cool. The system still has the VIR. There is a lot of condensation around the VIR. What should my gauges read?
camaroguy
Posts: 5
Joined: Wed Dec 28, 2016 1:22 pm

Re: 1976 Firebird A/C HELP!

Postby camaroguy » Tue May 29, 2018 6:59 pm

Sorry typo it should read 1976
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Cusser
Posts: 322
Joined: Sun Apr 24, 2016 6:29 am

Re: 1976 Firebird A/C HELP!

Postby Cusser » Tue May 29, 2018 8:02 pm

Don't most R-12 systems read about 30 psi low and 260-280 psi at about 1500 rpm with all fans working, at about 85F ambient?? Did you charge by weight to system specifications?? Did you use cans - all doesn't get in !!
Dougflas
Posts: 209
Joined: Mon Apr 18, 2016 6:10 pm

Re: 1976 Firebird A/C HELP!

Postby Dougflas » Wed May 30, 2018 10:08 am

Those systems have a sight glass on the VIR so charge until the glass is clear. With your gauges connected, engine at 1200 to 1500 rpm, disconnect the blower resister, does the low side drop to approximately 30 PSI? If not, start looking at the POA inside the VIR ass'y. If Tim does not have parts for the VIR, I may still have some. Your fan clutch may be weak also. Try misting the condenser with a water hose. If the high side drops like a rock, look at the airflow across the condenser. An old vehicle like that may also have air going around the evaporator due to the internal gasket material degrading inside the evaporator box.
camaroguy
Posts: 5
Joined: Wed Dec 28, 2016 1:22 pm

Re: 1976 Firebird A/C HELP!

Postby camaroguy » Wed May 30, 2018 4:38 pm

Yes I used cans. I’ll check the gauges again. Thank you guys. I’ll reply back

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