jw964c4

My 93 C4 dumps ac works for a while, then will start dumping hot air. I replaced the heater motor relay . Good for a week then the problem came back . My shop guys say that the control head is the culprit due to the random nature of the problem. I had it repaired by ASI in 2012, so I do not believe sending it back will fix it. As a hot weather fix , how do you prevent the heater blower/flaps from opening ? My thanks for any assistance.

Goughary

Just as an aside....three in one bike chain lube-cleaner is great for the flapper box once you free it with the pb blaster. Keep shaking it daily and keep spraying pb blaster, and then shake and let it sit. Shake it again and clean it w the chain lube and on until it's totally free. There should be zero resistance as has been stated. But if you don't coat the shaft the flapper rides on with some sort of lube, it'll hair rust itself solid again.

james944

Hi jw964c4,
If I understand your problem, check the mechanical connections for the servo in the front of the car.

Good illustration here:
http://web.archive.org/web/200811152...3.%20Reference

The plastic ball joints can fail and will let the mixing flap open to full heat randomly. If it is the ball joint you may be able to fix it with zip ties until replacements arrive.

Hope that helps,
James

jw964c4

Thanks James944. Checked out the servos this morning. After 6-8 minutes with the ac on, the servo opened and the hot air started. I messed around with the recirc and defrost settings and the servo closed and I had cold air again. The temp button was on full cold all the time. Really a bummer. Would the flap stay closed if the actuator arm is disconnected? Any suggestions are really appreciated.

james944

Hi jw964c4,

My flap would not stay closed with with actuator arm disconnected, it would open to full heat randomly. In your case it does seem like a control system problem.

For the summer, what you could try would be disconnecting the controller connection to the servo (the 5 pin connection in step #7 in the link above) and see if the system cools properly (not sure how it's wired and maybe disconnecting a servos would cause an error). That way you would still have the servo holding the clap closed to cooling but no controller signal randomly opening it.

You would just have to switch it when it started getting cold,
James

eddieb4

Here is a diagram in case it's helpful.

jw964c4

Thanks, I will disconnect the servo and see how that goes.

911Jetta

Web archive to the rescue!

jw964c4

Thanks James & Eddie, I disconnected the power lead as you said, the heat flap stays closed now. Can even run on vent now. I'll let you know if the control head can be repaired.
Jim

gt3sato

Hello
I'm new to the rennlist. I have the opposite problem with my 964, in that the heater fan is always on and blows hot air into the cabin. Even if I have the blue position on temp control and fan in off position, i still get hot air blown in. Any ideas how to resolve?

Spyerx

Check the heater flap,servo operation. If it's stuck in the warm position it will do this. There is a left and right servo. You pull cover off in frunk and you can see them.

Servo 2 and 4

Dr Mitch

I'd like to resurrect this thread once again - I'm getting hot air in cabin even if I disconnect the servos and manually close the heater flaps. I hear the little "tink" of the rear flaps when I open and close the doors. But something ain't right.

Just before weather started getting hot, the Freon was recharged and my indie (apparently) leak tested the A/C with no leaks.

A/C on does nothing - no cold air - but engine bogs a touch when turning on a/c - so something is turning on.

Will have to get it back to the shop and hook up to a Hammer. Hope I can get it sorted - may have to consider stuffing the rear heater vent hose/intake by the engine with insulation and disconnect the hose (previous owner did this and said it helped keep hot air blowing in).

No a/c, or rather, full heat all the time = no more 964 for me

Alex Sol

@dr mitch, i see you are in Toronto. Did you get your heat/cool issues sorted? i am digging into mine and hope to have it solved. i have working heat and ac now but needs some tweaking...

Dr Mitch

Yes, I did.
The heater flaps were sticking - I disconnected the hot air hoses (I replaced the old paper ones with nice duct tube from AirCraft Spruce) - I played with the flaps and there seemed to be a bit of grime / dirt in there - they seemed to work well - but would occasionally stick - so for the summer, I disconnected the hot air hose and put the foil tape over the intake to the HVAC - that made a HUGE difference in the amount of cold air in the cabin - so much so that my wife actually asks me to turn it down! (My servos used to stick, but I took them apart a couple of years ago and cleaned them and they all seem to be functioning fine now). Once the cold weather is here to stay I will reconnect the hot air hoses.

heliolps2

Great job on that...