our 86 vanden plas has great a/c but the heat does not come on at all when I change temp setting. Why is that?

 

Welcome to the forum holiday,

I've moved your question from General Tech Help to XJ40 forum. Members here with the same model will be able to help.

The first thing on my troubleshooting would be checking for refrigerant leaks and determining if the system needs recharging.

Graham

 

I think you are still in the wrong forum section. An '86 in the US is almost certainly a Series III, isn't it? That said, my impulse was to bring up sticky blend flaps - which, on an XJ40, can sometimes be remedied by a small amount of brutality (beating on the heater box in the dash with a wrench…). Perhaps it's the same on your car.

Cheers!
Scott

 

…although, now that I say that, it might not explain NO heat at all. Not sure all the blend flaps would stick at the same time. Hmmm…

Scott

 

Good call Scott, I thought 86 was pretty early for a 40 too but then I saw they were launched in Oct 86 ..so if this is a 40 (which I doubt) it would be one of the first I guess!!!