68 HEATER CONTROL VALVE (ABSENCE OF) - Chevelle Tech
2001 General Tech questions from 2001

 
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post #1 of 6 (permalink) Old Sep 27th, 01, 5:56 AM Thread Starter
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Apparently 68 Chevelles did not have a heater control valve to shut off the water to the heater core. Just the opening and closing of the doors inside the heater and air cond plenum is what controled the temp (I guess). The heater core in my son's 68 started leaking so I disconnected the heater hoses and looped one to bypass the water. WOW! THE AIR CONDITIONER IS FREEZING COLD NOW!!! Has anyone rigged up a heater control valve on their 68 (like maybe on a 70), other than installing a manual shutoff valve in a hose?

Or, was the 68 SUPPOSED TO HAVE a valve, and maybe someone in the past removed it?

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[This message has been edited by DZAUTO (edited 09-27-2001).]
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post #2 of 6 (permalink) Old Sep 27th, 01, 6:07 AM
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Yes, if it's factory A/C there should be a vacuum operated valve mounted on the front passenger side fenderwell.

Jim H
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post #3 of 6 (permalink) Old Sep 27th, 01, 7:35 AM
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Year One does list a valve for '69 and up models, but nothing for the '68. If you have a shop manual or assembly manual you should be able to figure what type (if any) valve you need. It probably would be pretty easy to adapt a valve to your car.
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post #4 of 6 (permalink) Old Sep 27th, 01, 1:03 PM
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There should indeed be an inline water temperature control valve mounted to the passenger side inner fender for 68. I believe it is cable controled, rather than vaccuum. Part number 3400672.

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post #5 of 6 (permalink) Old Sep 27th, 01, 4:42 PM Thread Starter
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Then, if that is the case, my is gone, and there is no evidence of anything to actuate the valve (loose vac hose or cable). Is it possible that a 68 300 Delux didn't get a heater control valve with factory AC? Could some of you guys who have a 68 with factory AC go raise your hoods and see what your cars have in the way of a valve in one of the heater hoses?

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Tom Parsons
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post #6 of 6 (permalink) Old Sep 27th, 01, 9:21 PM
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On '69 and up the valve closed with vacuum and opened with lack of vacuum. On '68 it was the other way around. Mine was missing, but this is the way it was shown in an old Heating and Air book at the local parts house. The '69 had provision for mounting the valve on the firewall, but the '68 didn't have this (again according to the book at the parts store).

I also had vacuum lines running into a block on the temperature control lever from the firewall, but mine were cut off at the firewall and no valve was present when I got the car. The HVAC control panel was broken, and no more good to me. I found a few more panels from other '68 Chevelles, but each one was different. I think this had a lot to do with the confusion from the UAW strike during those production runs.

I'm not sure about the "concours correct" way to install it, but this is what I found in my research. I installed a '69 valve on mine simply because it was in stock at the parts house and I'm not concerned about originality. It was also nice to have a bracket mounted to it. Now I just have to figure out a clean way to control it from the cockpit. For now I just disconnect the vacuum under the hood when I want it hot.

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[This message has been edited by cjlandry (edited 09-27-2001).]
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