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Blower motor will only run on low speed, except it speeds up a bit when I put some sideways pressure on the switch in #3 position (???).
The switch tests good. The high speed relay appears fine inside. I didn't actually test it, but it is not in the circuit on #2 and #3 position anyway.
The blower motor resistor looks like new. The motor isn't making any unusual noise at the slow speed.
I see there is a capacitor in the hot wire to the motor- could that be an issue?
Looks like if the motor is bad, a lot of stuff has to come out (a/c car).
Thanks for any help.
The easy way to test the heater fan motor is to apply 12 volts directly to it. I bet here is a resistor coil pack that is on the heater box under the hood. I know on my 73 with AC, the resistor coil is how the two slower speeds are controlled, for high speed the resistor coil is bypassed.
First, do check your blower motor as Eliredandblack recommended.
Power from the 25amp A/C Heater fuse first passes through the Function Control Switch.
You can see in the drawing, Circuit #50 enters the Function Control Switch and also jumpers directly to the LO contact of the resistor.
With engine OFF, ignition switch in the ON position you should hear your Blower Motor running slowly.
You will also have voltage at the Brown Wire at resistor, ignition switch ON position.
Blower motor will only run on low speed, except it speeds up a bit when I put some sideways pressure on the switch in #3 position (???).
You answered your own question, replace the switch. When I was kid, my mom would shove matchbook covers under the dial of the TV tuner until I was old enough to learn about Radio Shack's TV tuner cleaner. Rode my bicycle to Radio Shack to buy can's of TV tuner cleaner and made money fixing the neighbors TV's
My 78 came with a howling blower motor (bearings shot) from the prior owner. Easy fix even on a/c car. Motor unbolts from housing. Don’t think I had to remove anything else. The capacitor is for radio suppression. A small mirror was helpful to find all the attaching screw heads and I used rtv to seal the flange on the install. The new motor came with a cheap fan that was deformed enough that it hit the case on rotation. Ended up using the OE fan on the new motor
Oops. Never mind. Another senior moment.
After every component checked out O.K., I actually went and operated the system correctly.
The car is super low miles, I hadn't sat in it in two years, and I never drive it.
It finally dawned on me that the a/c or heat has to be switched on to enable the blower speed switch. Duh.
I appreciate all the input and sorry to sound the false alarm.
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'78 Blower Motor Problem
