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#21
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1971 Pontiac GT-37 Car is a junk yard dog and maybe one day will be restored. |
#22
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Yes, they do.
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#23
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I should've added this happened yesterday with no climate control operating, except for open windows.
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#24
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I completely re-worked the system in my 69 during restoration a few years ago and learned a bunch about it. Before the repairs I always got a bunch of heat coming into the car- not good when you live in Georgia.
The way that the 68-72 "flow through" A/C system is designed there is always an open path between the heater core and the car interior. The dampers control where the air goes and how much fresh/cooled air is blended in, but they do not isolate the heater core. Instead the system uses a vacuum-operated water cutoff valve to keep hot water from flowing through the heater core when the lower slider is in the far left (cool) position. A vacuum switch located behind the controller closes the valve. If the water cutoff valve is missing or not working then you will get heat in the car no matter what. You should see the valve mounted on the top front of the suitcase under the hood. The fan speed position switch does not shut the fan off. But the main selector slider has a switch that cuts power to the system when in the "off" position (far left). If everything is intact and working right, with both upper and lower sliders in the far left position the fan should not run and there should be no heat. So first thing to do is to try driving the car with the sliders set that way. If you get heat then the water cutoff valve is not closing. In my case the water cutoff valve was bad, and water/antifreeze must have got sucked into the vacuum line because the vacuum switch behind the controller assembly was ruined. Sourcing up a new valve and a new vacuum switch was quite a challenge, but getting it working properly eliminated the heat in the car- except when I want it.
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1969 Lemans vert, matador red, 462 CI, 3.07 12-bolt posi 1974 455 TA, admiralty blue/red interior HPP "cover car" - sold "The best way to show a car is to drive it" Last edited by PontGuy; 05-19-2014 at 12:37 AM. |
#25
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Also worth a mention- the norm/vent switch just turns the A/C compressor on and off.
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1969 Lemans vert, matador red, 462 CI, 3.07 12-bolt posi 1974 455 TA, admiralty blue/red interior HPP "cover car" - sold "The best way to show a car is to drive it" |
#26
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Thanks PontGuy. That is great information.
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#27
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Thank you very much for the thorough explanation; even my non-automotive-oriented wife understood it. |
#28
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Yeah that was the simple "wife-friendly" version. Getting into the details things are a bit more complicated
Quote:
From what you describe your cutoff valve may be frozen. Easy to check if it's working- with the system in cool position the heater hoses at the valve should not be hot since the valve should prevent water from flowing through them. Then if you push the lower slider to the right the valve should open and the hoses should quickly get very hot. Also if you are getting a lot of air with the fan off, then maybe the fresh air damper in the kick panel is not closing. Easy to check that too. Just pull the passenger kick panel and watch what it does in the various selector positions. It should be fully closed with the system off.
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1969 Lemans vert, matador red, 462 CI, 3.07 12-bolt posi 1974 455 TA, admiralty blue/red interior HPP "cover car" - sold "The best way to show a car is to drive it" |
#29
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PontGuy, thank you for the suggestions. Worth doing of the Memorial Day weekend!
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#30
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My 72 Luxury Lemans does not have that cutoff valve.I have not seen one on an A-body 72 era,some F-bodys i have noticed it on.Tempts me to install a manual valve on the supply side to the heater core though.
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72 Luxury Lemans nicely optioned These cars are meant to be driven, so enjoy the hell out of all of it - not just look at it when it's clean. |
#31
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Hmmm, I know that the heater box is the same and the control system is the same. And I owned a 71 and a 72 that both had the valve. So did a bit of searching and found this:
http://thepartguy.com/ac-controls-gtolemans.htm Looks like they eliminated the valve mid-72. Not sure how they kept the heat out- probably didn't.
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1969 Lemans vert, matador red, 462 CI, 3.07 12-bolt posi 1974 455 TA, admiralty blue/red interior HPP "cover car" - sold "The best way to show a car is to drive it" |
#32
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I had a 72 GTO back in the early 80's - so this is from old memory - but I remember it working as someone previously described - the fan always runs... and so the cool-warm selector is always active in terms of determining what type of air enters the car - even with the top lever all the way left.
The '69 description is a good one - but I think the system design was changed between '69 and '72 so those details may not hold for '72. If you are still getting hot air in at your feet when the bottom lever is full left, its likely just a stretched cable and/or bad flapper door and/or misadjusted cable... the door may not be snapping all the way closed when the lever is full left. There is a detent in the heater box that functions to snap it closed and seal it - good chance that detent isn't being activated.
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1969 Judge, 4-speed, CR/Parchment, Quasi-Survivor, #'s match - under restoration |
#33
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Nope, the systems are identical through 72 (except for late 72's not having the water valve which I just learned about myself.) The 69 I have now was just the first time that I went all the way through one of these systems and figured it all out. If you open the link everything being sold there matches with my experience over the years. And they have some great pictures. I wish I had found that site when I was rebuilding mine because they look like an outstanding source for hard-to-find parts.
In fact I have a pristine (rebuilt) 70-72 controller assembly that anyone here is welcome to for free if they need one. Laid side-by-side I found it to be exactly the same as the one in my 69 except for the angle of the face plate. I stole the water valve vacuum switch from it but otherwise it is complete, including the switch that shuts power to the fan in off position. There is a lot of confusion out there about how the A/C system works. It is not at all obvious and I guess not many have done a complete tear-down like I did. Also the non-A/C box is altogether different which adds to confusion. Bottom line is that the cable-driven flapper door diverts air coming into the box from the suitcase, one way through the heater core and the other way bypasses it, but does not isolate it. In either position the heater core is open to the heater vent even with the system full off. Crazy design if you ask me.
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1969 Lemans vert, matador red, 462 CI, 3.07 12-bolt posi 1974 455 TA, admiralty blue/red interior HPP "cover car" - sold "The best way to show a car is to drive it" |
#34
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