Heater question

WildWilly

WildWilly

True Classic
If you're following along in the Discussion forum, you will know that I'm taking out my dash to have it recovered and lots of other work done at MWB. Another issue I have is that the heat is stuck in the on position, so when driving, I have lots of warm blowing. With the dash removed, I was able to drop the blower motor box and will be cleaning that tomorrow. Does anyone know what's my issue with the sticking control? I can't move the temp slider and can't see exactly where it all goes to shoot some lube in there to see if I can get whatever is seized up moving again. Any ideas would be helpful. If I can't solve it, I'm sure MWB can! Thanks....
 
It's most likely s stuck valve. The valve is bolted onto the heater core and can be accessed from the passenger foot well. It is not hard to replace, but is is a bit frustrating due to the tight area and positions you need to work in.

The bandaid fix is to put a ball valve in the heater hose back in the engine bay. At least you can turn off the heat till you can really fix the heater valve.
 
I'm with Jim, most like the valve is stuck (rusted) open. Really the only fix is to replace the valve. But with the dash already out it should be easier to do than normal. Also check the controls and cables after they are disconnected from the frozen valve. Trying to force them while still connected to a bad valve will break the plastic arm on the control. Lube the cables before reassembling.

To replace the valve, look for prior threads where others have documented it. I found one for a AC equipped car (different valve), but it may help a little.
https://xwebforums.com/forum/index....-control-valve-replacement.27435/#post-228926
 
WildWilly said:
If you're following along in the Discussion forum, you will know that I'm taking out my dash to have it recovered and lots of other work done at MWB. Another issue I have is that the heat is stuck in the on position, so when driving, I have lots of warm blowing. With the dash removed, I was able to drop the blower motor box and will be cleaning that tomorrow. Does anyone know what's my issue with the sticking control? I can't move the temp slider and can't see exactly where it all goes to shoot some lube in there to see if I can get whatever is seized up moving again. Any ideas would be helpful. If I can't solve it, I'm sure MWB can! Thanks....
Click to expand...
+1 with Jim and Dr.Jeff. Valves are relatively cheap (unless you have A/C, OEM valves for those are unobtainium but IIRC someone has discovered a workable substitute), and with the dash out it'll be a comparative "walk in the park" to replace. Don't forget to get the oddball rubber orings/gasket thingies when you order the valve!
 
Yup, with the dash out, now is the time to make sure everything in the heater system works. Make sure the fresh air vent flap opens and closes. Even with the heater valve stuck in the hot position, you should be able to close the fresh air flap so no air would flow through the heater core.
 
Also take the time to open up the box and thoroughly clean it out. You will be shocked to see all the crud growing inside of it. A real health hazard frankly.

Test the heater core as well. They can rot out and leak...a real mess and a total pain to replace later after everything is reinstalled.
 
If you have a 1300 car, the heater core can be recored by a rad shop.
The 1500 has a plastic design that cannot be recored.
I don‘t know when they switched designs.
 
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