gsimon767

Just reinstalled my AC system to factory correct. AC works fine but vent setting blows warm air through the dash vents even on a cool 60 degree day.

Is air supposed to come in at the passenger kick panel or just through the dash vents? Any theories why the air is warmed through the dash vents?

My hood seal is good and the seals on the mix door seems to be good since the AC blows cold air.

Maybe I just don't understand how the vent system works.

Mountainoakie

The A/C (MAX or NORM) will automatically blow thru the vents but when you put the selector on VENT the A/C doesn't operate. Only ambient air blows out of the vents.

SwampeastMike

The "vent" position just directs the air through the dash vents. It can be heated just like in the "heat" position by moving the temperature wheel in 75 I think towards "warm". That said, the air coming out should be at or very near ambient with the temperature wheel all the way to "cool".

Do some digging to find out how your hot water cutoff system works. It's purpose it to shut down the flow of hot water through the heater core. I know how the system works for '78+ but am not certain about what came before.

gsimon767

My research indicates, at least in 75, there is no water shut off valve in Air Conditioned cars. Non AC cars most likely did have the valve. AIM manual does not show it for AC. Not much room for it. See attached picture of 77K mile original owner car.

My heater mix door seems to close tightly but maybe seals are weak. Or maybe without shutoff valve it's the nature of the beast to pass warm air. Maybe that's why they did include water shutoff valve in 76 and later cars.

SwampeastMike

That's my guess. From what I read here it's mainly the pre-'76 owners who go to sometimes extreme lengths to reduce cabin heat.