Dean_Fuller

Filled the system last spring with 3 cans of R12 after checking for leaks and adding a new dryer....worked well for a few months until the blower went bad. Replaced blower with a good used one just a couple weeks ago and tried the A/C with no luck. Hot air and no clutch engagment. Jumped the clutch and still a no go so I pulled a vaccum for 16 hours...held fine so I assume there are no leaks. Added one can (12 oz) R12 and the rear a/c started to cool...another can and I am back to cold A/C....where did the R12 go without a leak???? Also I now have a water drip in the drivers side floorboard. Drips off the back side of the tray close to the center console....cold clear water so I assume its condensation from somewhere but where....any ideas on the leak and or the drip???

Thanks in advance.

Manfred

Hey Dean, as far as the drip goes, see my post from earlier today regarding AC drain clogged. Not much there but there's a link to another thread where Roger chimes in. Also, do a search for AC drain--there's a few threads that are somewhat helpful but not great.

As for R12 leak, are you sure it's a leak? My AC was fairly warm 'cause my heater valve gave out which causes a heat-always-on problem. When you turn on your AC you end up with a luke warm combination. The AC will blow fairly cold when the engine is cold but gets warmer as the coolant heats up. Not sure if this might explain your problem. You can try pulling vacuum directly on the heater valve just below the airbox on the passenger's side to see if it holds vacuum.

jcorenman

Dean,

Holding vacuum (15 psi sucking in) is no guarantee that an o-ring will hold 120-150psi pushing out. If you have rear air, then the fitting under the pass-seat is a prime leak candidate- both of our cars have had leaks there. That fitting is not as mechanically rigid as the other tubing-nut connectors and doesn't do well with old/hard o-rings.

It is easy to get to from under the car, if the system is empty then I would just change those o-rings on general principles.

The heater valve problems we've seen (also two-for-two) were not with the vacuum actuator, but rather a seal which comes partially loose inside the valve and which prevents the disc from completely sealing the water passage. It was pretty obvious with the valve removed.

Cheers,

Dean_Fuller

Jim,
I will check that area for leaks with a sniffer ( I need to buy one I guess ) . Guess I didn't think about the difference in pressure.

Manfred,
Very interesting...I parked the car so that the driver side is lower than the passenger ( side of hill) so that sounds like the drain for sure.

Manfred

Yeah, it seems like this is common way for the heater valve to fail but in my case it was actually the vacuum actuator component that failed (same result--heat always on). The vacuum actuator is easy to check without removing the valve--all that's required is removing the airbox to get to it. To check the inside you actually have to remove the heater valve.

By the way, if it does end up to be your heater valve and you end up changing it, make sure you get a new hose for between the heater valve and the engine block (it's about 2 inches)--apparently that hose likes to fail and is easy to replace WYAI.

StratfordShark

But if temp lever is at full cold position, I thought a microswitch overrode the mixer flaps which would normally mix the cooled air with air from heater matrix, and close the flaps completely?

If that's the case then even with faulty heater valve (valve or actuator fault), you should get cold air with temp at extreme left.

j.kenzie@sbcglobal.net

Yep!

dprantl

An A/C system is sealed, so the R12 must be leaking out. Never just use vacuum to find leaks. The high-side reaches close to 300psi, which is a very far cry from -14.7psi (29.9997 inHg). I use nitrogen gas at about 120psi to test A/C systems. It's cheap and has found every leak for me so far.

Dan
'91 928GT S/C 475hp/460lb.ft