heater questions

[Kurt Combs]

I just finished replacing my heater core, dashboard control unit, and related cables. It is really cool to have heat and a defroster that works as it is getting really cold here lately (for northern California). I do have a couple of questions that I hope someone can answer though. First, does it matter which hose the control valve is installed in? I don't remember whether it was supposed to be in the hose coming from the intake manifold or the water pump. It is now connected to the hose from the intake manifold and seems to work fine. Second, my blower seems to only work on the highest setting and I am wondering if I need to change the switch or is the riostat bad? If it is the riostat it is going to have to stay the way it is as I am not going to pull the heater out to change it. Third, what does the riostat do and if defective can I by-pass it?

Thanks in advance,

Kurt

[fordman]

i don't remember on the heater valve. more than likely the switch is bad. if the reostat goes bad then the heater motor wont work at all. its just a coil of wire. once it breaks its done for. how do you spell reostat any way?

[AlleyCat]

Kurt, the valve is right.The hose from the manifold is the supply hose.Convection ( heat rises) and water pump pressure push coolant into the core.The other hose goes to the suction side of the water pump.

What you are calling the rheostat is the heater resistor.It works by varying the resistance in the power supply to the blower motor to control it's speed.Low speed has the most resistance, medium has less resistance and high speed bypasses the resistor and sends battery voltage to the motor.

All bypassing it would do is give you 3 high speeds.

[AlleyCat]

i don't remember on the heater valve. more than likely the switch is bad. if the reostat goes bad then the heater motor wont work at all. its just a coil of wire. once it breaks its done for. how do you spell reostat any way?

rheostat

[fordman]

i realized that just before i saw how you spelled it. thanks though.

[Kurt Combs]

Ok, since the heater only has one speed which is high, either the switch is bad or the resistor, or I didn't get the resistor wire connected correctly. The resistor looked fine when I had the heater disassembled and I could not see what I was doing when I plugged the wire into the backside of the heater housing. Good chance I did not plug it in the way it is supposed to connect. I will check that tomorrow morning.

Thanks everyone for the input.

Kurt

[basketcase0302]

Kurt,

The switch is pretty easy to ohm out, (or test).
Here's the wiring on it, thank you Keith!

http://www.fordification.com/images/sch ... heater.jpg

Jeff

[Kurt Combs]

Yes Sir, the heater works better with all the wires connected correctly! Seems I didn't get the wires plugged into the resistor terminal when I was reinstalling the heater unit. After feeling around behind the heater for the correct direction of the terminal and getting the wires plugged in, all speeds on the blower motor are working and just in time for the snow and forty degree daytime weather we are having. Thanks everyone for the input, and especially thanks to Keith for the wiring diagram.