Heater fan won’t cut off
- Thread starter Sonny
- Start date
PurpleBeeper
Well-Known Member
I'm no expert on this, but I can think of two possibilities:
1. Short in the fan switch (my guess since it's a '70)....or maybe the wiring
2. Some much newer cars have the fan on really low all the time (but I don't "think" this applies to 70 Plymouths....mine shuts off as far as I can tell)
1. Short in the fan switch (my guess since it's a '70)....or maybe the wiring
2. Some much newer cars have the fan on really low all the time (but I don't "think" this applies to 70 Plymouths....mine shuts off as far as I can tell)
Sonny
It’s all fun til the rabbit gets the gun.
Yes you’re right. ‘70 b body.
PurpleBeeper
Well-Known Member
I thought of something else....there's a chance that something shorted out in the blower motor resistor. I believe that is what actually controls the speed of the blower motor with a series of resistors. The switch basically just picks the a different hot wire & each hot wire goes through a different number of resistors...more resistors, slower fan speed.
Anyway..... that blower motor resistor.... actually resistor(s) is right above your feet on the passenger side going into the heater box. You can see it. Just one multi-wire plug and I think two screws that hold it in. Maybe something is messed up (shorted) inside there? It's really easy to look at it. Be gentle with it though since I don't think they are reproduced.
I suggest you look at a wiring diagram, but I "think" one of the wires comes OUT of the resistor and goes to the blower motor. The other wires come from the switch (each one will be hot only when the switch is on the position for that wire) & something like 3 resistors. One hot wire goes through no resistors (high speed), another goes through 1 resistor (med speed), another goes through 2 resistors (low speed)...not correct, but something like that. Maybe get a meter & wiring diagram and figure out what's up that way?
Anyway..... that blower motor resistor.... actually resistor(s) is right above your feet on the passenger side going into the heater box. You can see it. Just one multi-wire plug and I think two screws that hold it in. Maybe something is messed up (shorted) inside there? It's really easy to look at it. Be gentle with it though since I don't think they are reproduced.
I suggest you look at a wiring diagram, but I "think" one of the wires comes OUT of the resistor and goes to the blower motor. The other wires come from the switch (each one will be hot only when the switch is on the position for that wire) & something like 3 resistors. One hot wire goes through no resistors (high speed), another goes through 1 resistor (med speed), another goes through 2 resistors (low speed)...not correct, but something like that. Maybe get a meter & wiring diagram and figure out what's up that way?
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