Re: 735 HVAC Troubleshooting

[tgmedin <tgmedin@xxxxxxxxxxx>]

Fellow  E23 owners,

I am having trouble with the HVAC on my '86 735 and can't seem to locate the problem source.

The pushbutton unit started to act up awhile back so I ordered rebuilt  a pushbutton unit
along with the thumbwheel control unit  from Programa and installed them per instructions on
Callan's website. I now have no control of anything. The default defrost circuit does not
even work. I can hear and see some of the actuators work but I have no blower or air
conditioning. I verified the small fuse that supplies power to the pushbutton panel and it
is OK.
I removed the drivers side kick panel to access the control unit and I can not get it to
move no matter what pushbutton I push.
What signals the control unit to operate?? Is it the P/B panel?? The aux. vacuum pump in the
engine compartment works OK and I can not find any major leaks.
I checked the relays at the blower and they both check OK. How can I check the temperature
sensor at the blower??
What would cause me to lose everything????
It's getting cold here in PA so my wife says I need to get this fixed. Any and all comments
would be appreciated.

TIA,
Tom in PA

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