JPS

Replaced footwell flap motor.
Replaced fresh air servo.
Clutch was engaging and condenser working. Clutch stayed engaged only about 20 sec at a time. Pressure on the cheap can replacement gauge showed 45 and 25 out of low side, so I let out some.

Now the pressure shows about 17 maybe, but clutch stays engaged, condenser isn't coming on, fuse for condenser is good. Air starts warm and never cools off.

The fact that the clutch stopped disengaging and the condenser stopper coming on...did I take out too much? Pressure still seems high relative to the specs referenced here.

No apparent leaks as the pressure stayed constant before I took some out.

wwest

Yes, you let to much out. Watch the video.

"condenser isn't coming on,..."

Condenser COOLING FAN fan isn't coming on? Sounds as if you have a trinary pressure control switch in which case the cooling fan only activates when the high side pressure is elevated to a specific setpoint. Low refrigerant will have both symptoms.

JPS

A) yes I meant cooling fan in the driver wheel well
B) if too much pressure and it was hot so I let some out, but now gauge still says more than the 9-16 lbs @ 77F ambient spec, and still hot, what am I missing? Is the cheap gauge just not accurate enough?

JPS

Ps I know how to put it in. That isn't tough. Being above the pressure spec and things not working is confusing.

nine9six

At 75 degrees ambient; from what I can tell, low side pressure s/b 35-45 psi, right?

nine9six

See post #12 here
https://rennlist.com/forums/993-foru...-a-little.html

1990-964

I have had a similar experience with the cold air not coming through the vents. My pressures are good but no cold air comes out. After taking the same route as you and replacing the R/H footwell servo and verifying that all others were working and replacing the 3 way pressure switch, no joy. I checked behind the CCU and did find the vacuum hose to the actuator disconnected. Re-attaching it did not do the trick, but manually actuating the arm did immediately let cold air flow from the vents. So I am still chasing a vacuum leak somewhere else in the system. Hope your have some luck getting yours resolved.

JPS

So I think that diagram is for other cars. According to this:
https://rennlist.com/forums/993-foru...eferrerid=7241, pressure should be 9/16 low for engaged/disengaged clutch respectively. However, going that low didn't get anything to work at all.

I drained out enough to get close to that low, and nothing really worked. Put 2 bottles back in, got it to about where it was before I started messing with it, and it is blowing nothing but warm air.

I forgot to pull the CCU...I was going to take a peek in there. Really hoping not a vacuum leak somewhere as that will be expensive to track down.

griffiths

The low side function of an ac pressure switch in a TEV system, whether it be single, binary or trinary switch, typically is to prevent the compressor clutch from engaging if system pressures are below a certain value, say 20 psi for example. What ever the low side value is so long as you have that minimum pressure the switches circuit (whether that be normally closed or normally open) should be satisfied.

TMc993

When the compressor and condenser fan are running, is the line coming out of the compressor cold/sweating/frosted? If it is, then I'd be looking at the functioning of the CCU and air circulation system.

JPS

Meaning it should or shouldn't be cold or sweating?

It was doing that when I was subtracting or adding r134, but I don't recall if it was or wasn't otherwise.

TMc993

If it is cold/sweating/frosty when the compressor is running, it generally means that the compressor is at least pumping cold refrigerant out toward the front of the car. My point in asking is that the compressor/condenser/evaporator may be working fine, but the CCU may not be opening the appropriate vent flaps to let the cooled air into the passenger compartment (When I turn my AC on/off, I hear flaps actuating and the airflow slows then picks back up)....Just a theory.

ToreB

You may have a faulty mixer servo or two. It is easy to test all the flap servos, see my DIY for details: www.porschehvac.bergvill.com
Cheers,
Tore

JPS

Already replaced 2 and tested the rest. Thx tore.

wwest

Clarification...

Since the low pressure, suction side, of the system will often go below the clutch disable setpoint during operation the pressure switch, whichever type, is always in the high pressure side.