1973olds98

Whats the wire that plug into the water valve for? And the vaccuum ?line..?/

TripDeuces

The vacuum line controls the opening of the valve, it's attached to the heater controls using vacuum to operate it. It's a heater control valve btw. As far as the wire I have no clue. Never seen a wire on a heater control valve. Unless it's attached to some kind of temperature sensor.

MDchanic

The '73's have a temp. sensor on the water valve that turns off the "Low" speed on the fan (which is otherwise always on) through the "Low Speed Relay" when the engine is below something like 40°F.

It's completely unrelated to the action of the valve, which turns off the hot water when you select "High A/C."

It can be dispensed with with no noticeable difference in operation (just short the wire to ground for "constant-on" low speed). I don't even think you can get the valve with the sensor anymore.

- Eric