An interesting feature on my 1997 Ranger: when you turn the A/C all the way to the "max" setting, the valve for the heater core closes. So you cannot adjust the temperature of the air coming out the vents if it's on "max".
A plus of this system is if your blend door gets messed up, your A/C should still blow cold on "max". I don't think this design plays well with automatic climate controls though. Another plus is you don't have a hot heater core in the middle of your dash barely separated from the air flow.
Do you have a car that does this? I know the old Chevrolets had a "max" setting on the A/C, and I know they had a heater valve, but I don't know if they used this logic.
A plus of this system is if your blend door gets messed up, your A/C should still blow cold on "max". I don't think this design plays well with automatic climate controls though. Another plus is you don't have a hot heater core in the middle of your dash barely separated from the air flow.
Do you have a car that does this? I know the old Chevrolets had a "max" setting on the A/C, and I know they had a heater valve, but I don't know if they used this logic.