ok I seached but I cant find the answer. I just lost it dont know what happened. is there a vacum hose or somthing I pulled off by accident? thnks brr its cold. snowing even.

 

i am not sure, but here are a few things i know about....There is (i think) a ported Vacuum switch in the intake manifold, Not sure if that has anything to do with it. There is also a possible stuck thermostat. or a clog in the heater core. Also a possibility of the heater control switch to switch from hot to cold could be bad.

Just some places to start. Hope it helps.

 

Check the vacuum line going to the heater control valve, if your car has one - different models & years vary.

Snow sucks...why did I move here? I'm an idiot I guess.

 

ok cool thnks guys Ill have a look

 

I'm not positive (never really am) but I think '87 was the last year without the hot water control valve - or maybe it was the first year with it. I know the '86 doesn't have it.

Do you get any air flow at all? Can you change the air delivery from the defrosters to the vents to the floor outlets, etc?

It's been a little cool here, too. I haven't quite finished setting up the new area yet, so it was even cooler than I liked in the garage. At least it was until yesterday afternoon:

 

My 89 Iroc has a hot water control valve.

 

i believe 87 was first year.