Heater Help.

E

edfiero1

Member
Joined
Apr 6, 2017
I have this new to me 84 T-Type.
When I got it, the heater core was disconnected. The a-hole that sold it too me claimed the heater core had a leak. I had a shop pressure test it and they tell me the core is fine, so they hook up it up for me and now I get lots of nice heat.

Only problem is regardless of what the blend control is set to, I still get heat, so obviously the heater core was disconnected so he didn't roast in the summer time.

How do I troubleshoot? (In order of what's easiest to check first and cheapest to replace. Is the problem in the blend control or with the heater control valve?

Thanks
 
I havent had that issue on my GN but on my SS mc, it was my heater control valve

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Any suggestions on how I troubleshoot this? I know it 'could be' several things. I would like to begin eliminating some. Since its still hitting the mid-70's during the day, I'm not really needing a lot of heat right now. :)
 
What Mikestertwo said, check the arm behind the glovebox. You can order a new one or fabricate the arm back into existence. Check to see if the heater control valve is actually moving. when you switch from cold to heat.
 
does the temp blend slider button flop around? It should have some drag to it and you should hear the door moving.
 
A lot of times the shaft that the arm is attached to on the door is broken. I had a '84 Hurst Olds with the same problem.
 
If the water valve under the hood at firewall was bad you shouldn't be roasting. It's there so the a/c doesn't fight with hot air bleeding though the blend door. (turns off heat when a/c requested)
Thought for sure it's the blend door somehow.

You can take away or add a vacuum hose to the water valve to turn off the heat. I forget if vac opens or closes it. Boost may harm it, don't leave it long term, just for a test.
 
I doubt it's the hot water valve. I agree with No disintegrations. If the door is working you should not be getting "hot" air coming out of the vents even if the hot water valve is open. It just may not be as cool if the valve was closed. I think vacuum closes the valve. The drag you are feeling could just be the friction in the cable itself. I would verify the blend door is actually moving before I look else where.
 
Update: I dropped the glove box to see what was going on, and it appears as if cable is suppose to clip on side of the heater box however my clip / attachment point is broken. My issue is one of cable alignment. If I move the cable back to where this broken 'clip' is and then operate the heat lever, then the blend door moves as it should. However since the cable is not attached to the side of the heater box, it kinda flops down, and in this position, the cable doesn't slide when the heater control is operated. Re-positioning the cable makes it work fine.

Anyone have a picture of what this is suppose to look like? I could probably fabricate something if I knew what it was suppose to look like.
 
Same thing happened to my car years ago. Rigging that thing is going to be a trick to do it in a workman like fashion because of space limitations. To get me by I looped a zip tie around my trunk release button to the blend door arm. In Summer I let the loop hang free.

My plans are to remove the entire dash so I can do some wiring mods and fortify my 30+yo plastic HVAC stuff (and install an alarm) so I was just going to fix it correctly at that time.... That's been quite a few years now. :)
 
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