SeanR

Go grab some of that foaming condenser cleaner from Home Depot, spray it in the space between the blower motor and the evaporator housing. Located under the window cowl. Let it sit then either take a spray bottle or the garden hose and wash it away. Don't spray the crap out of it, but be gentle. Look under the car and see if you have a steady stream of water coming out right in the middle and if so, the drain is nice and clear.

alabbasi

Thanks Sean, I'll give that a go.

Regards

Al

alabbasi

Looked the job up in all data and it said to remove the hood. Was going to come back and ask Sean if this was the case but then found this thread : https://rennlist.com/forums/928-foru...leaning-3.html

Excellent thread!

alabbasi

I bought some of the coil cleaner and was able to spray down the evaporator and condenser , wash it down. it helped considerably with the air movement but not with cooling. I still thing that the expansion valve is bad but I did not have my R12 gauges on me to test.

It was really filthy down behind the fake firewall so I blew it out and hosed it down.




While I was at it, I thought I would take the effort to spray down the engine bay with degreaser and then wash it down. For some odd reason, the degreaser turned my valve covers from silver to an Austin Allegro beige.

Oh well. Onwards and upwards.

Tony

...and if you don't see anything...look at your floor mats. The drain is plugged.

alabbasi

Drain is for the most part clear. I ran the hose for a while and got a little bit of water inside the car. Given then volume that I was pushing through, this was nothing to be concerned about, although I'll blow the lines out next time the car is on the lift.

dr bob

I did the same thing early in my stewardship period. Got it rinsed with just a few dribble stains on the silver covers. But eventually the cam covers and the intake had to be refinished to get back to original silver. The beige/tan is the chromate undercoat peeking through, and is so common that many think the silver on the intake is supposed to have a champaigne or slightly gold hue to it.

By the time the paint gets to this stage, there's a separate but related need to replace the hoses and sensors under the intake, the seals and rubbing blocks under the cam covers anyway.

alabbasi

Quick update on this. I pulled the air cleaner assembly in order to get to the vacuum line to the heater valve but i could not really feel any vacuum, I don't know if that's me the line as the line is very thin.

I can say that the system definitely has a/c because the steel lines above the heater valve are ice cold.

I don't think that the issue is the heater valve however for the following reasons.

1) When the engine is cold and just started, the front a/c unit still blows warm air (it's around 95 degrees outside these days).
2) If I let the car warm up and then turn the heating on, it does blow warmer air out of the vents until I dial it back down again.
3) The rear a/c blows cold.

I'm wondering if there is a vacuum operated door that directs air from either the heater core or evaporator core and how to access it for diagnoses.

The 928 specialist site indicates that that's a yellow vacuum line to splice into however I did not see any vacuum with that color under the hood.

Thanks

MainePorsche

Check vacuum to your heater valve. Track the vacuum line from the brake MC to the solenoid in the center console, and the line from the solenoid back out to the heater valve. Check along its whole course.

Also is your heater valve attached in the right orientation ?
The black face should be facing the short hose.

Also check your heater valve. Does it hold vacuum ?

alabbasi

Will see if I can get a vacuum gauge on that line. Heater valve looks original and untouched for many years so I assume it is mounted correctly, but I cannot remember exact orientation right now.

MainePorsche

All the more reason to check it.

auzivision

With the engine off (no vacuum) the valve defaults to open. So another quick fix/test is to zip tie it closed and see if that works. If it doesn't, then the valve is leaking coolant; if it does the valve is either not receiving vacuum or not holding it.

Honestly, a new heater valve cost less than a vacuum tester and they all go bad... the valves that is. I'd replace the $15 valve first and then troubleshoot vacuum if that doesn't fix it.

dr bob

And I'd tie even a new valve closed for the remaining duration of AC season. I don't have a picture, but I drilled a small hole in the plastic frame so I could pass a small wire tie through and around the actuator arm.

We had a very mild summer until early August, so I didn't bother with the tie. Then a few high-90's days reminded me that it was time. The valve works fine, but when the engine is off the valve relaxes to open position, and theres convective flow from the engine up through the heater core. So a warm restart includes removing all the heat that migrated up from the engine, all the heat accumulated in the car while it was parked, etc, before you start feeling cool again. The wire tie trick saves ten to fifteen minutes off that cooling cycle, it seems. Probably less, but miserable hot minutes seem to drag on longer than sixty seconds.

alabbasi

Thanks, I have a vacuum gauge lying around and have no objection to getting a new heater valve. I'm just wondering if there is a heater door behind the dash that would switch between the a/c and heater core.

I'll check tonight or tomorrow and report back. Thank you all for your input.

Herman K

It may still be leaking/passing water on the inside (bad seal). You have test it of the car close it and try to blow through the water in port to see if it stops you from blowing any air by the inside seal (the same for any water flowing through)