4Runner blower problems

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Alex - 19 Dec 2006 16:46 GMT

Hi folks,

I'm trying to troubleshoot a non-working fan on a '91 4-Runner and was
wondering if someone can offer some tips. (The fan in question is the
inside blower fan/AC.) It no longer comes on. This happens at ALL
speeds, includiing the highest. I've checked whatever fuses I could
think of and even have given the 'CDS FAN' relays a few wacks with a
screwdriver, just in case they got stuck... No luck.

I've taken off the glove compartment and gotten to the motor, but am
not really sure what to look for there. I've disconnected what appears
to be the power supply wire to the motor and, with the fan switch
turned all the way up, hooked up a voltmeter to all the terminals,
every which way I could think of. I can't seem to register a voltage
there. (BTW, should I still expect to read somewhere around 12V DC
there, just like I do at the battery?) This seems to imply that
there's no power to the motor, which would then rule out the motor
itself. However, I'm:

1. Not 100% convinced that I'm measuring voltage in the right place and
in the right manner
2. Even if I am, am not sure where to go look for the problem at this
point.

I've also done my best at trying to measure voltage across the relay
terminals (again, CDS FAN #1 & 2, with the engine running and fan
switch all the way to ON). And again, I've been unable to register any
kind of voltage, but am not sure that I'm doing it correctly.
(Measuring across the 'already ON' terminals, not the switched ones.)

Can someone offer some ideas to try next? Could it be the switch
itself? Is there an easy way to test that theory? Should I just get
the right relays and try those? (Are the CDS FAN the right relays?
Where can I get them?) I've also read some references in this group to
a blower resistor pack on the motor, but it sounds like since the motor
won't come on even at highest speed, when the current should flow
directly to it, this may not be the culprit.

Please help before I do any more damage. I know just enough to cause a
blackout in the neighborhood. :-)

Thanks in advance,

Alex

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Ray O - 19 Dec 2006 17:39 GMT

> Hi folks,
>
[quoted text clipped - 4 lines]
> think of and even have given the 'CDS FAN' relays a few wacks with a
> screwdriver, just in case they got stuck... No luck.

I believe that the "CDS Fan" relay is for the condenser fan in the engine
compartment and not for the AC/heater fan.

> I've taken off the glove compartment and gotten to the motor, but am
> not really sure what to look for there. I've disconnected what appears
[quoted text clipped - 31 lines]
>
> Alex

You have a volt meter and access to the blower motor so you are in the right
area. Power to the blower motor passes through a resistor pack that resides
in or near the blower cage. Since you do not have voltage at the blower
motor, the next step is to work your way backwards towards the power source.
Problems with the resistor pack are common causes of blower problems so I
would check that next. If you look at where power comes into the resistor
pack, you can follow it out where it goes to the blower. See if there is
voltage coming into the resistor pack and coming out of the resistor pack.
If there is voltage to the pack but none coming out, then there is an open
circuit in the pack. If you are handy at soldering, look for a break
somewhere in the pack.

Signature

Ray O
(correct punctuation to reply)

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Alex - 19 Dec 2006 19:51 GMT

Thanks Ray. Am about to look at it. One question though: I was under
the impression that on the highest fan setting, power went directly to
the motor, bypassing the resistor pack. So, if the motor didn't work
even on the highest setting, then the resistor pack might not be the
cause. Or does power go through the pack (but not the resistors) even
on highest settings?

If I end up having to look at the switch, is there an easier way to get
at the sucker, other than taking off all of the panels in front of it?

Thanks again,

Alex

> > Hi folks,
> >
[quoted text clipped - 55 lines]
> circuit in the pack. If you are handy at soldering, look for a break
> somewhere in the pack.

Reply to this Message

Ray O - 19 Dec 2006 20:11 GMT

> Thanks Ray. Am about to look at it. One question though: I was under
> the impression that on the highest fan setting, power went directly to
> the motor, bypassing the resistor pack. So, if the motor didn't work
> even on the highest setting, then the resistor pack might not be the
> cause. Or does power go through the pack (but not the resistors) even
> on highest settings?

I believe that the wiring for the blower passes through the resistor pack
frame but not through the resistors with the blower on the highest speed
setting.

> If I end up having to look at the switch, is there an easier way to get
> at the sucker, other than taking off all of the panels in front of it?
>
> Thanks again,
>
> Alex

According to the pictures on this web site with instructions for installing
an accessory bracket
http://www.pro-fit-intl.com/Adobe/TY-70-90.pdf the switch looks like it will
take less than 5 minutes to get at it.

Signature

Ray O
(correct punctuation to reply)

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Alex - 19 Dec 2006 20:43 GMT

Thanks Ray. I got the Climate controls panel off, so it looks pretty
much like that picture now. The trick now would be to get to the back
of that panel, in order to get to the switch wiring and take in/out
voltage reading there... Can't seem to get at it w/o removing the
clock and the trim panel around it. Arrgghh...

Another follow-up question about the resistor pack possibility. Is the
resistor pack upstream or downstream from the blower motor plug (where
I'm taking the voltage reading). In other words is it like A) or B):

A) SWITCH --> RESISTOR PACK --> PLUG --> BLOWER MOTOR
B) SWITCH --> PLUG --> RESISTOR PACK --> BLOWER MOTOR

Since there doesn't seem to be any power at the PLUG terminals, then if
it's A), then it might be the resistor pack. If it's B), then it's
something else.

Thanks!

Alex

> > Thanks Ray. Am about to look at it. One question though: I was under
> > the impression that on the highest fan setting, power went directly to
[quoted text clipped - 18 lines]
> http://www.pro-fit-intl.com/Adobe/TY-70-90.pdf the switch looks like it will
> take less than 5 minutes to get at it.

Reply to this Message

Ray O - 19 Dec 2006 21:54 GMT

> Thanks Ray. I got the Climate controls panel off, so it looks pretty
> much like that picture now. The trick now would be to get to the back
> of that panel, in order to get to the switch wiring and take in/out
> voltage reading there... Can't seem to get at it w/o removing the
> clock and the trim panel around it. Arrgghh...

Once you get the hang of taking stuff apart, it gets easier. Removing the
trim around the clock and audio system does not look too difficult, and the
clock and/or HVAC controls are probably held with 2 orf 4 screws.

> Another follow-up question about the resistor pack possibility. Is the
> resistor pack upstream or downstream from the blower motor plug (where
[quoted text clipped - 10 lines]
>
> Alex

I am not real clear on what you mean by "upstream" and "downstream" and I do
not have a wiring diagram for your truck, but in general, power goes from
the switch to a relay, then the relay provides higher current power to the
resistor pack, and then power goes to the blower.

If the resistor pack has just 1 connector plug, then some of the pins on the
plug connect the resistors to the power supply (relay) and some of the pins
on the plug connect the resistors to the load, which in this case is the
blower motor. A wiring diagram would help identify where each wire and pin
on the connector leads to. With the fan switch on, I would think that there
should be power to at least some of the pins on the resistor pack plug.

If the switch is too hard to reach, look for a relay, fuse, or circuit
breaker for the heater fan.

Signature

Ray O
(correct punctuation to reply)

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Danny G. - 19 Dec 2006 18:14 GMT

> Hi folks,
>
[quoted text clipped - 40 lines]
>
> Alex

If you print #37 at this link it should help:
http://autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/16/1a
/4e/0900823d80161a4e.jsp

Autozone.com should have a complete repair manual and more for your truck there online and free.

GL Dan

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