I have a 1976 280s. 116 body type. This car has the automatic climate control. The type has temp control thumb wheel, 5 vertical buttons, and an on/off switch for the compressor. The blower should run with the comp switch in off. It does not.
Comp switch OFF... blower will not run in auto lo, auto hi, or defog. Blower runs in defrost at max speed.
Comp switch ON... blower operates as needed in all modes. blower speed varies as needed. after about 15 minutes, in auto lo or auto hi, the blower stops working. I can make the blower run again by going to defrost mode for about 1 minute, then going back to auto lo or auto hi and the fan will run for 10-15 minutes more. I can also make the blower run by turning the temp wheel down to 65. I just discovered this today. The blower will come back on in 10 to 15 seconds of lowering the temp wheel to 65.
The master vaccumn servo valve was replaced last summer. The climate control panel is original.
Any thoughts, questions, comments or help would be greatly appreciated.