Rex

When I turn the ignition on the blower motor starts running. All levers are in the off position. I was told by the previous owner that the AC control panel had been rebuilt.
Any thoughts, Thanks,
Rex

Lady72nRob71

What speed does it run at? slow or fast?
Try unplugging the fan switch under the dash to see if that get it to stop.
Pull the fuse for it if that is easier. This will help determine if the dash switch is stuck on or if there is a short from a different power source.

Rex

Rob, it runs in slow. will try your suggestions as soon as it get light. By the by you were correct about my turn signal question, it was the switch. I replaced it and all is well.
Thanks, Rex

TripDeuces

My 66 runs when you put the ignition on also. Isn't that their 'Flow Through Ventilation'? I think it's supposed to be that way regardless if controls are off or not.

jeffreyalman

what year car? later models (70 on???) had this feature. It was part of the flow-through ventilation - positive air flow to insure exhaust could not creep in

Fan runs on low speed in OFF position

I want to say it started in 69 with the omission of vent windows but every day I lose a few more brain cells

bgoble

My 72 does it also.

jeffreyalman

Also new for '71 was a flow-through ventilation system utilizing vents mounted in the trunklid shared with other full-sized GM cars and the compact Chevrolet Vega. It used the heater fan to draw air into the car from the cowl intake, and force it out through vents in the trunk lid or tailgate. In theory, passengers could enjoy fresh air even when the car was moving slowly or stopped, as in heavy traffic. In practice, however, it didn't work.
Within weeks of the 1971 models' debut, however, Buick—and all other GM dealers—received multiple complaints from drivers who complained the ventilation system pulled cold air into the car before the heater could warm up—and could not be shut off. The ventilation system was extensively revised for 1972.

I believe the change was the ambient switch which prevented the fan from running until the engine warmed up enough to heat the air

Lady72nRob71

Interesting - looks like it was a 'feature' on the 72 full size cars but not on the A-body.
I bet that feature could be on your 66, also.

rocketraider

Shouldn't do this on a 66 or 68 unless the fan start switch on the back of the HVAC head is wacky. On an A/C car, blower should start when any position except OFF or VENT is depressed. A heater only car should start only in HEAT or DE-ICE. A Comfortron car blower should not start until the coolant temperature sensor reads coolant at 120 degrees or higher.

Lever controlled Cutlasses and J-88s do not have the fan switch and those probably will start in any position, but I was thinking those cars had a positive OFF position on the blower switch?