A/C recharge pressure

[wa3vez]

1976 911S A/C recharging. Just finished recharging system after two years of not using. Pulled vacuum with no leaks or problems. When charging system, through low pressure port, the pressure went up to 70 psi. Also gas flow into the system was very slow. System temperature only goes up to 57 degrees. Low pressure runs about 70 psi. High pressure runs 250 psi. Do I have a low pressure obstruction? Expansion valve? Drier? Thanks

[Hladun]

You've probably overcharged your system. The low side pressure should be around 30 to 45 psi to give evaporator temperatures around freezing. On a chart I have 70 psi would give higher evaporator temperatures... around what you're getting. More is not better here!

[hcoles]

I don't want to highjack... but
Can someone please give a brief explaination of the basics of "filling" or "charging" an AC system?
What are the desired conditions for fully charged? How is the "sight" glass used?
Do you charge until certain pressures are reached? While the engine is running and AC clutch engaged? Does the ambiant temperature matter?

Thanks, sorry for a question that is probably on another post... please reply with thread if you know of one.

[rick-l]

Can't go wrong here

Very good auto AC forum

Make sure you have high and low side pressure, ambient temperature and vent temperature when you ask a question.

[wa3vez]

Not overcharged since intitial pressure was 70 psi when I started charging.

[rick-l]

Originally Posted by wa3vez

Not overcharged since intitial pressure was 70 psi when I started charging.

A full can of r134 will be at 70 psig at 70 deg F

[tcar]

That car came from the factory (if factory air) with R12, not 134a. Converted? Aftermarket?

Don't have enought info.

[hcoles]

Rick, thanks for the link... I've been reading...
-Henry