AC press readings and temp from vents

[marty]

Anyone know what the low and high press readings should be w R12 in the system (I have R12 compatible HC12)?  Also, what should the temp be from the vents (I'm getting about 52 F w my IR temp sensor).

[eaglebeek]

There are many factors that affect pressures...outside air temperature, inside-the-car temperature, engine speed, etc....that it would be difficult to say exactly what pressures are correct. As a general rule of thumb the high pressure side should be 7-10 times low side pressure. Example: if low side pressure is 30psi high side pressure should be 210-300psi.

IR thermometers are difficult for gauging air temperature. Instead they try to gauge the temperature of surrounding objects. Using a mechanical thermometer  held at the center duct you should get 42 degrees or less with the car closed up and the engine running at a fast idle...somewhere around 1,000rpm.

[marty]

Hmm, will try the regular thermometer.  I was running about 30 psi on the low side and about 150psi on the high side, outside air temp in the low 80's.

[rmick]

Those pressures are about right for R12. You should also get about a 15-20 degree drop in temperature across the evaporator. the inlet side as apposed the the outlet temperature

[JayRamb]

Where can one find an R-12 valve to the can to the AC compressor?!

I FOUND ONE ON EBAY!!! YAY!!

[macdude443]

When I had my R12 recharged last summer, with true R12, the shop read 39* at the vents on a 75* day.

[JayRamb]

Found one on eBay!!! Yay!!