Car AC question

System is running R12

At idle:

Low side pressure 35 psig

High side pressure 205 psig

Ambient temperature 95 degrees F

Humidity 54% (weird for Florida)

The AC cools fine at anything at or above 1500 RPMs. At idle at a stoplight it feels a tad weak, granted we've had extremely hot days and there is no tint on the car.

Are the pressures above ok? Or does it need a recharge?

Thanks!

Any other info needed, ask away and I will try to provide it.

Year, make, model?

1985 Mercedes Benz 500 SEL.

AC is all as it left the factory. Its a euro model with manual HVAC system.

What color is the car?

1988RedT2 wrote: What color is the car?

Mercedes code 702 Smoke Silver (Rauchsilber)

Air/moisture in system will do this.

Some of that pressure is not from refrigerant. Get the system vacuumed down for 40+ min before recharging.

Edit: Just noticed R12... That stuff was used before I ever worked with it but my prediction is based on what i see a LOT of for an R134a system. Pressures can be pretty normal but air doesn't cause anywhere near as much temperature drop when going from high to low pressure like after the expansion valve/orifice tube as it passes through the evaporator core.

Low side seems a little low, but I'm no R12 expert. What happens to the pressures at 1500 rpm? Low side to 20, high side to 275?

If high side goes really high, think restriction. If low side doesn't change much, look to the compressor.

I will check the pressure at 1500 RPMs this weekend and report back