Heater Fuse Mystery, HOTLY HOPEING!

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Richard - 25 Jan 2005 23:07 GMT

My wife is driving a 1990 4RUNNER without any heat for a month now!
The previous posting was helpful. I am wondering if there is a fuse
for either the front heater or rear, as both have now stopped blowing.
I understand it's likely the relay that is gone but I'd like to try
changing the fuse first. I Googled for over an hour without finding
specific info as to where is the fuse? I checked by the drivers
fusebox but doesn't seem to be one there. Does anyone know if the
blower motor can safely be directly connected to the battery? Would I
need an inline fuse for that? Any help or good link would be HOTLY
appreciated! (minus 25 degrees tonite!!!!!)

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Rich - 26 Jan 2005 00:41 GMT

dombijou@hotmail.com (Richard) wrote in news:6974d37e.0501251507.677a24d2
@posting.google.com:

> My wife is driving a 1990 4RUNNER without any heat for a month now!
> The previous posting was helpful. I am wondering if there is a fuse
> for either the front heater or rear, as both have now stopped blowing.
> I understand it's likely the relay that is gone but I'd like to try
> changing the fuse first.

According to my electrical diagram, there is a fuse for both the front and
rear blower motors. As to where they are, I don't know for certain.

They're both 20A fuses.

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---
Never trust a computer that you can lift. (from the Mainframe Forum)

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Rowdy - 26 Jan 2005 02:36 GMT

> According to my electrical diagram, there is a fuse for both the front and
> rear blower motors. As to where they are, I don't know for certain.
[quoted text clipped - 4 lines]
> ---
> Never trust a computer that you can lift. (from the Mainframe Forum)

I have a manual on CD and it says the heater fuse is in fuse block 3,
located behind the glove box.

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Guylaine J. Parisien - 26 Jan 2005 15:45 GMT

I have an 85 4runner. Her's how it works......
the heater blowers get their power from two control points. The ignition
switch puts power thru a 7.5 amp fuse to the two heaters relays and to the
main power window relay. [7.5 amps is enough to operate the relay coils] If
this fuse is gone these three relays are effectively dead. Neither heater
blower will operate nor will the power window master switches. These three
operate on relays that close on demand from the controls, supplying power
from other live circuits that are fused with 20 AMPs each for the two htr
blowers and a 20 amp circuit breaker for the power windows.
So if you have no power windows, [or somethig else doesn't work it might be
reated to your problem ], look for the 7.5 IGN fuse and then the blowers and
windows should work.
If you have power windows operating, then it's only the blower circuits. or
is something else not working?
The two 20AMP blower fuses get power from an 80 AMP fuse link [ a fuse in
the wire buried in the harness near the battery, even looks like part of the
wire] but it also feeds the ignition so if the truck runs it can't be that
unless your circuit has been modified from the 85 circuit.
So logically thinking
........ two blower relays don't fail at the same time? two blower on/off
switches don't fail at the same time? two seperate fuses don't fail at the
same time? ....... since I assume all other electrical items function
normally.....
It has to be the grounding of the blower circuit .
ground points are located ....
A .... under the left front pillar
B ... right front fender
C ... engine block
look for a broken or corroded wire on these ground points.
to see if grounding is the problem, find the ground wire to the rear blower
and jumper it to a new ground point and see if the blower works

> My wife is driving a 1990 4RUNNER without any heat for a month now!
> The previous posting was helpful. I am wondering if there is a fuse
[quoted text clipped - 6 lines]
> need an inline fuse for that? Any help or good link would be HOTLY
> appreciated! (minus 25 degrees tonite!!!!!)

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