No Heater Fan

[issjoe]

I just bought a 1990 Loyale 165k miles . Heater fan dosn't work. The
heater fan fuse is good. What steps do I take to trobleshoot?

 

[Brian]

To over-simplify, treat your fan blower circuit like the old battery,
switch, and light circuits we were taught as kids and ensure there is a
complete path for electricity going through the fan motor.

The fan motor runs on 12 volts, so you can take the thing out and put 12
volts directly to it and see if she goes round.

Your fan should have four, switch selectable settings, 1, 2, 3, & 4, and
perhaps off someplace as well. Speeds 1, 2, & 3 go through a blower
resistor which will be down by the fan motor, and speed 4 is a direct 12
volt feed. If 1, 2, or all of the first 3 settings were not functioning,
yet speed 4 was fine, one would say, bad resistor or connection thereto and
head to a junkyard to try and find a working replacement, or a dealership
for a new one if you're feeling rich. Since you say no settings are
working, perhaps you have a bad ground someplace, bad speed select switch,
bad off switch, or bad blower motor.

I would grab a multimeter and dig in, myself.

The blower motor fuse is good? Good. Check voltage there anyway.

Not knowing the most common part to fail, I would check each item in the
series on my way from the fuse to the blower motor itself until I found the
culprit, but hopefully somebody here will know which item goes the most
often, so you can start with that?

Some disassembly may be required.

~Brian

 

[issjoe]

To over-simplify, treat your fan blower circuit like the old battery,
switch, and light circuits we were taught as kids and ensure there is a
complete path for electricity going through the fan motor.

The fan motor runs on 12 volts, so you can take the thing out and put 12
volts directly to it and see if she goes round.

Your fan should have four, switch selectable settings, 1, 2, 3, & 4, and
perhaps off someplace as well.  Speeds 1, 2, & 3 go through a blower
resistor which will be down by the fan motor, and speed 4 is a direct 12
volt feed.  If 1, 2, or all of the first 3 settings were not functioning,
yet speed 4 was fine, one would say, bad resistor or connection thereto and
head to a junkyard to try and find a working replacement, or a dealership
for a new one if you're feeling rich.    Since you say no settings are
working, perhaps you have a bad ground someplace, bad speed select switch,
bad off switch, or bad blower motor.

I would grab a multimeter and dig in, myself.

The blower motor fuse is good?  Good.  Check voltage there anyway.

Not knowing the most common part to fail, I would check each item in the
series on my way from the fuse to the blower motor itself until I found the
culprit, but hopefully somebody here will know which item goes the most
often, so you can start with that?

Some disassembly may be required.  

~Brian






- Show quoted text -

Thanks for your advise Brian. I was reading about the resister
problem. Knowing that setting 4 is a direct feed clears things up. I
have no fan setting that work, so I'll start with the switch and go
from there.