1969 heater valves/plenum
Thread Starter
Racer
Joined: Sep 2012
Posts: 459
Likes: 6
From: Fort Worth Texas
1969 heater valves/plenum
I've got the dash out, and have already done a few "why not do it now" projects. My car is non AC. My understanding is the AC cars had a bypass valve on the heater hose so no coolant would go through the coils. What's the provision on the non AC cars?
The plenum has two vacuum actuators on it. Does one of these open a door in the plenum when heat is selected, allowing air to blow over the coils? Are there any seals inside the plenum itself which need servicing after so many years?
thanks
The plenum has two vacuum actuators on it. Does one of these open a door in the plenum when heat is selected, allowing air to blow over the coils? Are there any seals inside the plenum itself which need servicing after so many years?
thanks
Team Owner
Joined: Sep 2006
Posts: 31,214
Likes: 4,302
From: Westminster Maryland
Hi b,
The right side wheel on the heater/defroster control regulates the flow of air either over the heater core or not.
The wheel controls a bowden cable that moves a lever on the top of the heater box which swings the door open or closed.
You should be able to tell by operating the heater/defroster and feeling the change in air temperature coming out of the ducts if the seal on the door is still good.
The vacuum actuators you see control WHERE the air flows and are controlled by the left wheel on the controller.
Regards,
Alan
Bowden cable on lever on top of heater box.
The right side wheel on the heater/defroster control regulates the flow of air either over the heater core or not.
The wheel controls a bowden cable that moves a lever on the top of the heater box which swings the door open or closed.
You should be able to tell by operating the heater/defroster and feeling the change in air temperature coming out of the ducts if the seal on the door is still good.
The vacuum actuators you see control WHERE the air flows and are controlled by the left wheel on the controller.
Regards,
Alan
Bowden cable on lever on top of heater box.
Thread Starter
Racer
Joined: Sep 2012
Posts: 459
Likes: 6
From: Fort Worth Texas
Hi b,
The right side wheel on the heater/defroster control regulates the flow of air either over the heater core or not.
The wheel controls a bowden cable that moves a lever on the top of the heater box which swings the door open or closed.
You should be able to tell by operating the heater/defroster and feeling the change in air temperature coming out of the ducts if the seal on the door is still good.
The vacuum actuators you see control WHERE the air flows and are controlled by the left wheel on the controller.
Regards,
Alan
Bowden cable on lever on top of heater box.
The right side wheel on the heater/defroster control regulates the flow of air either over the heater core or not.
The wheel controls a bowden cable that moves a lever on the top of the heater box which swings the door open or closed.
You should be able to tell by operating the heater/defroster and feeling the change in air temperature coming out of the ducts if the seal on the door is still good.
The vacuum actuators you see control WHERE the air flows and are controlled by the left wheel on the controller.
Regards,
Alan
Bowden cable on lever on top of heater box.
What has to be done to change the seal on the door? Does the whole plenum need to be pulled? I have the dash out and have easy access. When the cable is manipulated, you can hear the door shut, and it seems like the seal is shot, listening to the sound it makes
Team Owner
Joined: Sep 2006
Posts: 31,214
Likes: 4,302
From: Westminster Maryland
Hi b,
The plenum does need to come off the firewall.
I'm not sure how the door seal is accessed. Might be through the core opening in the plenum or might be an access panel on the back side of the plenum near the door.
I think the test is not how the door sounds but rather does the temperature at the outlets change when the door is closed.
You should be able to test that even with part of the dash out.
Good Luck!
Regards,
Alan
The plenum does need to come off the firewall.
I'm not sure how the door seal is accessed. Might be through the core opening in the plenum or might be an access panel on the back side of the plenum near the door.
I think the test is not how the door sounds but rather does the temperature at the outlets change when the door is closed.
You should be able to test that even with part of the dash out.
Good Luck!
Regards,
Alan
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,481
From: Southbound
Cruise-In II Veteran
Pro
Joined: Jul 2006
Posts: 505
Likes: 25
From: Buxton Maine
Hi BellaireRoad, I recently rebuilt my heater box. 69 with no AC. The seals inside were junk. Got a rebuild kit from doc rebuild. Really good kit and came with new rivets to put it all back together. Wasn't a hard job and not expensive.
The vacuum actuator on the left side is a dual acting one. I had to replace mine since one side was bad. It can send air to only the defroster, only the heater (lower side), or in it's free state, splits it and sends to both heat and defrost. The other actuator is single acting and either lets air in or not. Now's the time since it's such a big job getting it out with everything in place. Rick
The vacuum actuator on the left side is a dual acting one. I had to replace mine since one side was bad. It can send air to only the defroster, only the heater (lower side), or in it's free state, splits it and sends to both heat and defrost. The other actuator is single acting and either lets air in or not. Now's the time since it's such a big job getting it out with everything in place. Rick
Pro
Joined: Jul 2006
Posts: 505
Likes: 25
From: Buxton Maine
Yes, a metal cover plate that is riveted to the F/G box using small aluminum rivets. There are two rubber/foam seals. One on each flap if you will. Mice had chewed the seals on mine so they had to be replaced. The rebuild kit I got from the Dr. was top notch.
I also wanted to mention to BellaireRoad…. iirc, there is no provision to stop the coolant from flowing through the heater core on non AC cars. Some owners have installed a manual ball valve in one of the the heater hoses in an attempt to lower heat in the cabin. Rick
Rick
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