WesternDevil

Apologies if this topic has been answered already but I couldn't find any info on it. I'm not a car guy so if someone mentioned this fix for a different car, I wouldn't know if it works on mine. I recently bought a 1988 Delta 88 Royale Brougham. No heat coming out of vents, but the fan works fine. Windshield fogged up constantly and I figured out it was the heater core. I had the heater core replaced and the thermostat replaced which fixed the foggy windshield problem but I'm not getting heat out of the vents while driving. The air temp is hot while idling but gets cold while driving. Any ideas or posts you could direct me to would be much appreciated.

Once again to sum it all up.
-1988 Delta 88 Royale Brougham 86K miles (if that matters at all)
-Electronic temp controls/Electronic everything
-Replaced heater core and thermostat
-Fan blows air
-Fan blows hot air while idling but cools down to cold air while driving
-Temp control works. Tested while idling and temp controls work fine.

rustyroger

Sounds to me like either restricted flow of coolant to the matrix, or the blend door isn't functioning as it should. I believe there is a water control valve in the system that is normally open and fully closed when the AC is set to max, maybe that has stuck in an almost closed position?.

Roger.

WesternDevil

Thanx for the reply. I'll look into this.

Olds64

Was your coolant flushed when your heater core and thermostat were replaced? If this has never been done your coolant system may be clogged. Check the condition of the coolant by removing the radiator cap when the engine is cold. The coolant should be translucent with a light green tint.

Check the function of the air doors by selecting defrost, vents and floor with the car idling. You should hear the air doors activate and feel the air at the various vents. If there's a fault the system is designed to default to defrost.