[Black Dawg]

NOTE: this is on an MKI.

I'm at my wit's end. I pulled apart my whole dash board to replace my heater core, since it was dumping antifreeze into my vents. I got that taken care of, heater core is replaced, no leakes, only now I have discovered another problem. The temperature slider does not work! I believe this to be an existing problem and was there before I took everything apart, so it is not something that I forgot to hook up. The temp is stuck on full cold no matter what I do to the slider. If it were a cable control, this would be no big deal, but since its a bunch of wires and vacuum lines and solenoids, etc., I figure I'm pretty well screwed as far as getting this thing to work properly ever again. Anyone have any suggestions? I refuse to ask or deal with a shop on this as I'm sure the bill would be way too much. My only thought was to run a cable to the temperature box and then hook a knob to it, sort of like a manual choke controller and use that to control the temp. Any other help?

 

[CDarthvader]

I have the same problem, Although I think one of the relays are bad in mine becuase it switches from hot to cold randomly

 

[Junkie]

Test the VSV valves,should be on the pass inner fender.Don't have a mkI manual,but also bypass the under hood heater valve and see if it goes to permanant hot.If so,then it's electrical or vaccuum.These systems aren't that complicated if you have the TSRM.Not sure how the Chilton's etc. cover the subject.

 

[CJSREDPRA]

Sam,

Do you have the 79 - 81 MKI Specific Haynes manual?? (the one w/ the brown cover??). If not, LMK, I'll keep my eye out for one on Ebay.

Will poke around in my copy of the Haynes manual & my original 81 TSRM manuals. Will see if they come up w/ something.

 

[Black Dawg]

The only manual I have is the Haynes Supra 79-92 manual, not much (in fact no) help as far as my problem goes. If you could find a specific manual that would be great, Chris. It's cold driving around with no heater!

 

[CJSREDPRA]

Struck out Sam....

I looked at all of my 81 TSRM books AND the 79 - 81 Haynes MKI specific manual. Nothing covers how to diagnose the vacuum system for the heater valve - VSV. Closest thing I found, was how to remove the heater fan & the heater core in the Haynes manual.

Best guess now, is to look in the online 86 TSRM??? It's more or less similiar, only difference is that the MKI Auto A/C system does not have the air temperature sensor thingy that is underneath the MKII console bin, and it does not have the ambient daylight sensor that is on top of the dash. Compared to my 85, the 81 MKI Auto A/C system seems to be a very crude/rudimentary setup.

 

[MAD_83supra]

I know the VSV valve allows hot water to enter the heater core.. Do you have hot water flowing?>( hoses are all hot)
I remember if there is no vacuum going to the firewall then the Auto temp control will not function.

 

[Black Dawg]

Best guess now, is to look in the online 86 TSRM???

Got a link to that thing?

 

[CJSREDPRA]

Yep,

http://www.cygnusx1.net/supra/library/TSRM_MKII/index.html