So now that my car is finally running pretty good after working on it for a year, it's time for some different questions. Just recently I repaired the linkage on the heater core that changes the temp (it goes from the cable to some other arm bit). Now I can once again adjust temp, but if I set the location setting to "vent" and the temp to "cool" outside temp air comes through the dash vents, but hot air comes out of the heater core in the foot wells. So far the only way I can figure to not get hot air is to set it to "max AC/recirculate" (no AC installed btw); but then I'm only getting back the cabin air which is not always desirable. Thoughts? Is this something that could be solved without tearing the dash apart (again)? I just fixed the blower motor too (PO hot wired it to high only on a toggle switch), so now low and med are a thing. And yes, windows will do the majority of cooling, but sometimes you just want some air moving around ya know. Anyways, any advice appreciated. Oh yeah, it's a 1980 GS if that makes any difference. Cheers and happy 4th!

 

Hey Ben-

The vent flow is independent of the heater core air temp/flow I believe. This setting directs air from outside around the heater's core with a flapper door.
If you are not able to get the temp to change, it may be that the heater control VALVE is frozen up? These DO fail. If it has locked in-place in the heat-mode, then you need to at least manually try to flip it so that the valve shuts off. I believe this is on the driver side of the heater box. Check and see if the control wire is actually pivoting the heater valve or just bending because the valve is frozen. Might want to bone up on what the PN is for a new valve and see if Mazda still stocks them. Or pick a setting and leave it there, hot; or cold...
The valve may be under the heater outer covers, so yeah, might mean partial dash disassembly to get at it...


Stu Aull
80GS
AZ