John:
Does the fuse blow on high speed, low speed or both? You need not toast
more
fuses. Pull the fuse in question, and check the resistance between the heater
side of the fuse clip and ground with the fan "ON". The ignition key should be
in the off position while doing this test, the transmission should be in first
gear and the wipers should be off. This will disable all the other circuits
except the heater.
Flip the heater between both speeds. Does the resistance change by more
than
1 ohm?
1. Yes - it toggles between a few ohms and almost zero.
Leave the fan speed switch in the high resistance position, replace the
fuse, and switch
the ignition to the accessory position. What happens?
The fan does not turn at all: The fan motor is shorted or perhaps
seized.
The fan runs at high speed: GRN/YLW wire from switch is shorted to
ground.
The fan runs at a low speed: GRN/BRN wire from switch is shorted to
ground.
2. No - The resistance changes by less than 1 ohm.
The switch is bad, or miswired.
A seized fan motor would not be uncommon, and can be repaired. The car
is 30
years old, and the motor shaft is mild steel, so it is prone to corrosion.
Also, in 30 years the motor lube probably dried up as well.
Vance
Vance Navarrette
Cogito Ergo Zoom
I think, therefore I go fast
-----Original Message-----
From: 6pack-bounces@autox.team.net [mailto:6pack-bounces@autox.team.net] On
Behalf Of John VanNorman
Sent: Tuesday, March 24, 2009 11:55 AM
To: 6-Pack
Subject: [6pack] heater fan blowing fuse
<snip>
So it seems to me that either the heater fan or the heater fan switch
is drawing too much current. But how would that be possible? Also, we
had all the gauges off during our hibernation work - is it possible
that we could have hooked the heater fan switch backwards (but would
that even make a difference?).
John V.
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