Had A/C recharged with R 12 today. Glass is clear, no bubbles. Still, not cold enough. With A/C off, blows hot air. I checked heater valve - temp set to min(65), lever on heater valve is up, in position when pushed up by spring. If I move temp to high(max), lever on valve wouldn't move.When temp set to min, If I push lever down(against the spring pressure) some times it stays down for a while, then gets back up. In which position valve is closed. Also, could it be problem with vacuum line from heater control unit. How to check that?
Please help
Regards
Art20c

 

http://members.rennlist.com/pirtle/zvac_tests.txt

 

Heater valve is normally open (fail open). So when the car is off, the valve is open for sure.

 

So, with air box off, and engine off I should look at valve to see lever position and it will be open (hot air)?

 

Follow Rez's link to John's site - but yes, the arm will be up with no vac/eng off.
Set at cold, eng on , the valve will/should receive vacuum - and the arm will move downward to close the valve: if this does not occur, there is either vacuum missing, or the valve is actuator is shot.
You can wire the arm down to test the efficiency of the AC.
BTW, I want your receiver - mine does not have a sight glass

 

Garth,
it's strange that you don't have glass, all porsches I had got glass sight on dryer/receiver (87 951, 86 911, 94 968). About my valve-when i move temp handle on control unit, air temp changes. But I saw valve open when temp was set to min. isnt that something?

 

If you have good pressures in your system. I suppose they were checked?? You could have bad positions in the air handler box of the vents, so no good ac would be flowing. Check the blue vacuum check valve at the brake master cylinder . Take off and see if there is vacuum pulling from it to the black vac line. If none, replace blue valve. then continue. Then see if the black line is going to the vacuum distributing manifold (rubber manifold) at the air handling control , solenoid strip. It could be off. Its a big complicated system. Have to start at the beginning. You could have anything bad, maybe bad expansion valve, vacuum leaking from one of the other vac points, bad vent motor, bad solenoid at the vent to outside which is up from the fuse panel and letting in hot air. I have some of these parts if you need to buy. okbarnett@tampabay.rr.com