Before I spend a lot of time digging into this, are there any common issues that cause the heat not to shut off completely on a D1? Seems like a damper door isn't shutting off fully, or maybe a bad damper door gasket.. I'd rather fix the problem right than put a shut-off valve in the heater line (which I've done on other vehicles in the past). What are your thoughts?

Thanks in advance.

 

is the fan still running or does it seem to be 'leaking' hot air from the vents even with the fan off?

have you ever pulled the dash assebmly apart... too much fun! If you end up doing that I suggest replacing dash bulbs and thoroughly cleaning the condensor and drain lines while you are there.

the foam seals on the vent doors is a common problem and will allow air infiltration.

 

Thanks,

There is warm air coming out when the temp dials are as far over toward the cold temps as possible. Not as much warm air when the fan is off, but still some coming through. Worse when fan is on. It's definitely not HOT air, just some leakage. It's ok in spring/fall, but in summer, it's annoying. Been like that since I bought it. I've had the dash partly apart (and apart on other vehicles) but my main question was if there were any adjustments, or vacuum motors that I should inspect first.

 

First we need to determine if it is ambient temp or from the heater core.
Remember it is summer time so with the a/c off the air coming in will be warm.

While moving it is normal for air to come in the vents, this is "ram air", air being forced into the cabin through the HVAC system.

It could be a stuck heater valve, that is the valve you added to other cars but had to manually open and close, this does it when you turn the temp ***** on the dash, it could be bad, stuck, missing...who knows.

If the air coming in is just "warm" then I would say it is a bad blend door or blend door seal.
if it is "hot" air then I would say it is the heater valve.