[tamathumper]

Thanks for the comment! I'm relieved to see that units are quite available compared to a couple years ago, so if it's the unit I'll just get one and swap it out. I'm practically working two jobs at the moment so I don't have much time to put into kanoodling.

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[tamathumper]

Issue is now completely resolved. I disassembled the unit and found two resistors that were too close to nearby components, and moved them so they were no longer touching (red circles in picture), and I cleaned up all the contacts at the same time.



Temps are in the high 20's, and there is no clicking even on rough road surfaces.

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[flash]

weird - how the heck did they move and suddenly create a problem? i thought this was supposed to be "solid state" not "i'll be here today but there tomorrow" state.

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[kwikt]

Wow, interesting fix. Might have to disassemble my spare and take a look.

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[tamathumper]

https://en.wikipedia.org/wiki/Whisker_(metallurgy)

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[gbarrier]

I'm betting "cleaned up all the contacts" may be the key here.

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[Inkedupfatboy]

Tama that was a cool article -

not too bad when it happens on a 20 year old car - bad when it happens at the local nuke plant.



Now that I have read this, I seem to remember the TV repair guy telling me about this at the appliance store I worked at. Glad you got it solved. What a weird one.

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[Sears]

Sorry for being MIA, I finally took my car to a different shop and had this sorted out. I had a bad unit, it was swapped for a used unit and now all is well. I did also have a bad heater valve (wasn't opening, so no heat) so now I'm back and fully functional. Thanks for everyone's help, it's nice to have the 68 back and fully operational.

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[alausch]

I'm having a very similar issue with my cab. When I turn on the A/C button, it cycles hot and cold air. I hear a clicking noise, maybe from the footwell. It's hard to tell.

 

First off, It WAS blowing hot air when the A/C was off almost all of the time once the engine was warmed up. I replaced the heater control valve, the old one was very sticky and hard to move. That actually solved the "hot air blowing all of the time" problem. Shout out to Clark's Garage...

 

Now I think that there were ultimately two different issues, and I've eliminated one. I think there's an issue specifically with the solenoid while the air is on. Does the solenoid connect to the head unit? Has anyone does a test or had the same issue/replaced the solenoid? It's part #  944-659-215-03    

 

May 21 2018: Here's where it gets interesting, in addition to this post. I continued to troubleshoot. One thing I noticed while driving the car yesterday...the mixer flap is moving by itself. I can see it opening and closing, without touching any of the controls. Here's the catch, the mixer clip is NOT broken. What in the world? I have a used Denso actuator for the mixing door/flap. Maybe I'll change that first. We'll see. If that doesn't work I guess it has to be the control unit or the heater solenoid. Like above, I'm starting to feel more confident about the control unit at this point if this doesn't fix the issue.

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