I hate it when I may have caused an issue but check this out....

So After months of a engine out rebuild, re-seal, refresh and then some paint work both of which took 6 months...about 4 months longer than planned or promised I finally get the car back.

So this is where I come in to play, I was going to do the APR chip, I did the chip on my 951 no biggie, they wanted a picture of the outside of the ECU box and the chip. I pull back the carpet and am like WTF who over designed this!

There is no room to remove it without ripping up glued carpet as the mounting bracket extends in both directions needlessly further than required. I am doing some strange twister action to finally see this thing...

I look at it and decide no way I am opening this thing up that looks like a 1990 era's CPU to a crappy server. So I go to put tall back and that was fun.

So I pull back into garage and I hear some clicking, repeatedly. ok. I had enough fun for the day and decide to button it up later. I do, in the garage.

That Monday it had a date with the body shop and driving there and nothing but hot air is coming out...with HVAC controls all at 0 and on cool. AC is not working now.

Sigh. What did I do.

Take to shop and not sure if this was related or just bad luck the vacuum line leading to the manifold had pulled out the nipple. That was the culprit they said not my ECU endevear. Unfortunately as I was driving away I heard the clicking still and hot air.
Back in shop they check the solenoids, and had two on hand ...nope. But if you tapped this air bundle you could recreate the click...almost like an improvised dual climate control where your passenger can kick and change the temp! a new feature!

They were not comfortable with wiring so I took it to my car stereo shop that metered everything, we found the wires that couple replicate the clicking, The first one was a no joy fix. The second I was certain we got it it, a loose connector to a motor of some kind...we have it on video. Everything worked fine.
Drove home on PCH, AC was cold and everything was greta in the world. Until today pulling it out of the way to ready my other car for Parade this coming week....click click click. AC works fine ( tested) as does heat but clicking.

I have researched this and most of the info is coming from the older 94X models. I am still certain I did this with that foray into the ECU. Is that where I should go back and see if I disconnected something...it's just we can replicate it easily by touching wires not leading tot he ECU area.

ANY information would be appreciated. TIA

 

This is the best most thorough trouble shooting I have seen on the HVAC system by Tom M'Guinn here at Rennlist https://rennlist.com/forums/924-931-...l-testing.html

There is certainly good info at Clarkes Garage Site on 944 late HVAC. And then if you have access to the late 944 workshop manuals.

Hard to troubleshoot without following one of these guides to check a lot of boxes.