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Old Nov 27, 2024 | 07:55 AM
  #25 (permalink)  
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dedwards0323
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Joined: Nov 2008
Posts: 8,488
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From: Upstate SC
Default Re: Hot Air when cool selected, AC

Originally Posted by M60A3Driver
I will try this as well.It might solve my warm air problem. I'm still going to have to figure out my fan speed controller.
I'm thinking that's a bad potentiometer.
Thanks,
John
When I had the sporadic fan issue on my 2007 Coupe, I took the HVAC Control Module out of the Vertical Console, separated the 2 control boards, filed a small notch in the HVAC Control Module plastic surround so the horizontal board would fully seat into the pin connection, applied a small of epoxy glue to keep the boards together, & then re-assembled everything (see CL770's attached procedure). I also took the time to spray some electronic cleaner on the pots on the backside of the HVAC Control Module. After I got everything together, I still had an HVAC fan speed problem. Only after I installed a new blower motor resistor did the HVAC fan speed problem go away. And the system is still working today per design specs. Did I fix multiple issues during all of this? Yeah, I did!

1) The Control Boards seating was fixed permanently.
2) Using Electronic Cleaner on the pots was a temporary solution & may surface again later on.
3) Replacing the Blower Motor Resistor will last until it fails down the road - it is a wearable item.
4) And while the procedure to kinda 'flush' the HVAC Duo Valve of any residue accumulated from the cooling system cleared up the lack of cool air during A/C Mode on the DS of the Dash, I'll re-build the Duo Valve sometime in the future. Easy task to do. (Note: So is the need to re-build the HVAC Duo Valve a clear indicator that the Cooling System needs to be Drained, Flushed, New Thermostat installed & Re-Filled with new Coolant? Probably!)
 
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Last edited by dedwards0323; Nov 27, 2024 at 08:10 AM.
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