Heater/AC doesn't work on high

[Call Her Bu]

Anyone know why my heater doesn't work on high? The AC is currently not working. It's an 81 Malibu.

 

[84dragcutlass]

Could be the high position of the fan switch has gone bad or there is what i think is a resistor if im not mistaken on the top of the heat/ac box that can go bad. It sits down inside the box and it almost triangle shaped and held down by two screws, there is a wide flat plug that plugs into it. Im sure someone on here has a picture but youll know it when you see it

 

[jetsetw31]

Could be the high position of the fan switch has gone bad or there is what i think is a resistor if im not mistaken on the top of the heat/ac box that can go bad. It sits down inside the box and it almost triangle shaped and held down by two screws, there is a wide flat plug that plugs into it. Im sure someone on here has a picture but youll know it when you see it

X2 on the resistor, it controls your fan speeds. High is direct battery power to the fan and the lower settings go through the resistor. If that don't fix it, then it's the switch itself. Try the resistor first, it's easier to replace. It's also called a fan module.
T

 

[pontiacgp]

There is a connector on the left near the front of the valve cover. There is a 10 gauge red wire that feeds the high speed blower that is in that connector. Make sure that the wire and/or connector has not been burnt by the exhaust and there is good current on each side of that connector

 

[darbysan]

X2 on that connector- it is usually the culprit. Next would be the High Speed Relay, mounted on the HVAC housing. Resistor in High Speed simply bypasses the voltage directly to the motor. Switch could be bad or dirty.