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'69 Coronet AC/Heater Control Sliders Quit Working

Aeronet

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The sliders quit working this morning. I push them and they dont switch from defrost to heat, etc. I take it the switch went bad. Has anyone had this problem and what did you do about it?
The fan is stuck on defrost and I can't turn it off.
Any help is appreciated, thanks.
 
Since it is vacuum controlled, I would check to see if the hoses are all intact first.
Start at the engine vacuum tee and work your way to the heater box. Since your fan runs, it probably is not a fuse. More than likely a vacuum issue.
 
Agree likely a loss of vacuum. Do you here hissing in behind switch? Idle change?
 
No hissing or idle change that I noticed. I'll check again.
 
I doubt you would hear much of a hiss from such a small hose. If everything seems to be intact, the vacuum control switch behind the sliders could have failed. They have been known for it. You will have to remove the two screws and drop the controller down to inspect it or replace it if in fact it has failed. I could also be one of the 1/8" hoses or an actuator on the heater box too. Plenty of things to have caused the problem.
 
I doubt you would hear much of a hiss from such a small hose. If everything seems to be intact, the vacuum control switch behind the sliders could have failed. They have been known for it. You will have to remove the two screws and drop the controller down to inspect it or replace it if in fact it has failed. I could also be one of the 1/8" hoses or an actuator on the heater box too. Plenty of things to have caused the problem.
I took the screws out but it didn't want to drop down. There's a piece of chrome trim along the dash that looks like it's keeping the control panel from dropping down. I'm gonna go out and work on a little later when it warms up a bit.
I have some hearing loss so I'd have to know what I was listening for. If it's an internal leak in the switch would it make any noise?
 
The temperature controls are wire /cable driven. For years when switching flow direction, it goes to defrost then starts banging like a mallet on a wooden table. Rhythmic. Loud and heavy. I’ll be watching the thread. Take pictures if you pull it apart.
 
The temperature controls are wire /cable driven. For years when switching flow direction, it goes to defrost then starts banging like a mallet on a wooden table. Rhythmic. Loud and heavy. I’ll be watching the thread. Take pictures if you pull it apart.
I will.
 
Recalling from memory hot to cold is cable driven, but on A.C. cars there may be a vacuum for heat and defrost. @JimKueneman will know for sure.
 
Recalling from memory hot to cold is cable driven, but on A.C. cars there may be a vacuum for heat and defrost. @JimKueneman will know for sure.
You are correct. Vacuum controls the venting (heat, defrost, etc.). It's an AC car. It has the horribly expensive dual heater core.
 
Somewhere out there is a YouTube video where the vacuum switch is repaired with a ferrel and super glue.
 
Somewhere out there is a YouTube video where the vacuum switch is repaired with a ferrel and super glue.
I was wondering if the switch could be repaired. I looked online and they are available either new or NOS. I'm getting ready to go out and see what's going on.
 
Ok, fired it up, listened for vacuum leak. Couldn't hear anything. Engine runs the same as it always does. Idle speed unchanged.
 
Screws out, won't drop. That chrome trim piece that runs the length of the dash is coming out.
IMG_4153.JPG
 
So @JimKueneman has on his restoration page how he repaired. Seach for his pages and you will find the rebuild of the fan and vacuum switch.
 
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