a/c question

sylvester · sylvester's Garage

hi.. i have a 1979 porsche 911sc and my a/c is getting about 60 degrees at idle, when i put the gauges on my car with the engine running its reading low of freon, but with the engine off its reading to much freon on the low side only what needs to be done any ideals thank you for the help.

rattlsnak · rattlsnak's Garage

what are your gauge readings? (both high and low, A/C on and off)

and im assuming this is still an R12 system?

bigchillcar · bigchillcar's Garage

sylvester..shoot member 'jim sims' a pm. he's the resident a/c guru and can walk you through anything. rattlsnak's just a pilot..what do they know..

ryan

rattlsnak · rattlsnak's Garage

Yes, but I'm an A&Ps worst nightmare... a pilot with a 20 year ASE Master Tech certifcate.

sylvester · sylvester's Garage

im using r134 let me check my gauges and i'lll get back with you tomorrow.

bigchillcar · bigchillcar's Garage

Quote:

Yes, but I'm an A&Ps worst nightmare... a pilot with a 20 year ASE Master Tech certifcate.

ahhhhhhhhhhhhhhhhhhhhhhhh!

Jim Sims · 05-08-2006, 07:10 PM

Compressor's Maxwell's demon should be replaced if the freon won't stay on the high side when it's not running.

Seriously, the low side pressure should rise when the compressor is not running.

Given the sparse data and considering probabilities I will conjecture the system is low on R134a, contains excessive moisture and has too much mineral oil in it.

Check pressures with deck lid down, engine running at idle and at 2000 rpm. High and low side running pressures, air temp 2 inches outside of the decklid condenser, output temperature at vent closest to the evaporator are the minimum information needed. Also if the system cycles between blowing cold, then hot, then cold, etc. is a clue.

bigchillcar · bigchillcar's Garage

i just love makin' extra work for jim..

Dixie · Dixie's Garage

Quote:

...but with the engine off its reading to much freon on the low side...

And I bet with the engine off it's too low on the high side. Think about it for a moment. When the compressor is off, the low and high sides will equalize in pressure.

Read the gauges with the compressor running. The manual says to do the reading at 2,000 rpm.