ac fan-fuse 27 pass comp keeps burning out


david ranger

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Thanks RonD and EricB.
I ran the car for 2 weeks without the AC on, using just the fan.
So with the mode selector switch on the VENT position, 1 click counter clock wise.
Fuse 27 did not blew.

If i put the mode selector switch in any other position and thus activating the AC,
the fuse blows. And he does do that now basically immediately while previously after days or weeks.
And he does it with a hard pitch.

If i run the car without AC so just with the AC the same loud pitch sometimes occurs interruppting the sound of the radio
but without any fuse blowing.

So if I interpret the info you so generously provided correctly,
the short should be in the mode selector switch or in the cable GRY/YEL running from
that switch to the connector C2280B in the SJB and to the blend door actuator.
The actuator which I as advised have disconnected since to rule out that factor.

The other wire BLK/LT GRN could not be the problem as the VENT position is also connected to that
wire and i have no short when running just the fan without the AC.

I know how to measure resistance in the cable.
How to measure the model selector switch itself?
 


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RonD

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So as per wiring diagram, the grey/yellow stripe wire on pin 1 of climate control selector has 12volts with key ON
And if in OFF or VENT the fuse does not blow

When any other position is selected then the Purple(violet) wire on pin 2 gets that 12volts and fuse blows

The purple wire connects to pin 41 on computer

So I would pull out the climate control panel and unplug the wiring connector
Key OFF
test purple wire with OHM meter to ground, 0 to 5 ohms is a short to ground

If shorted then I would pull off the Computers connector, and retest just to make sure its not a computer issue


If purple wire has high ohms or N/C(no connection) then purple wire is OK, problem may be inside the switch itself
Key still OFF
Put connector back on the switch
Put ohm meter on pin 2 purple wire at switch and ground
Cycle switch to see if ohms drop low

There is no Ground on this switch so not sure how it would short
 

david ranger

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Thanks Ron D.

I pulled out the climate control panel and unplugged the wiring connector.
I measured resistance number 0.00 on both the purple and red wire.
I measured resistance number 1 on the other 2 wires.
The same result with PCM connector disconnected.
I performed all readings with the ground of the battery disconnected and once with it connected
as i do not know if that has an influence. Now i guess not ;-)

So what conclusion can we draw from this? with the below mentioned also taken in mind:

If i put the mode selector switch in any other position and thus activating the AC,
the fuse blows. And he does do that now basically immediately while previously after days or weeks.
And he does it with a hard pitch.

If i run the car without AC the same loud pitch sometimes occurs interruppting the sound of the radio
but without any fuse blowing.
 


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