AC fan motor problem
 

So today while driving my 2005 Silverado 1500 with the AC on full blast, I smell burning nylon or plastic in the cab. I sniffed around under the dash, and on the passengers side, on the far right appears to be the fan motor for the AC and heater. This is where the smell was coming from. The wires were a bit warm leading to the motor, but the motor itself was not hot. No smoke, just the scent of burning insulation or something. My AC/fan control switchhas settings 1 through 5. The smell finally stopped, but now,the fan will not work on setting 5. Settings 1 through 4 work normally, but on setting five, there is no fan function at all.

Has anyone else experienced such a problem? Can anyone suggest where I start troubleshooting.

If the circuit was overloaded or something, I would have expected a fuse to blow, but this is apparently not the case.

Thanks & Regards,

RE: AC fan motor problem
 

The blower resistor burnt up..

you need a resistor and a connector..WARNING..that connector is over a hundred bucks.
pretty easy to install though

RE: AC fan motor problem
 

Thanks for responding, I don't have a service manual. Can you give me a hint where to look for this resistor and what it looks like.

Am I right reading from your post that the resistor can't be replaced without replacing the 100 buck connector?

I assume that once I find it, it will be the connector that smoked also.

Thanks,

RE: AC fan motor problem
 

I dunno if your truck has a cover under the hvac case or not...cheaper trucks don't...

but get on the right floorboard...remove the big cover if you don't see the wiring and such.

NEAR the blower motor is the resistor...two 5.5mm screws hold it in the case....unplug the connector...its a black,flat connector with about 7 wires.....maybe 14 gauge wires.

once unplugged,look in the connector and you'll see its melted.DO NOT TRY to short-cut anything if it is melted...get a new connector and new resistor.

you'll need a mini-torch for the heat-shrink connectors

RE: AC fan motor problem
 

Well Argon:
Your advice was right on the money. After receiving your last reply, but before responding, I grabbed a flashlight and took a look under the passenger side dash. Since mine is a "El Cheapo" work truck, there was no cover to remove. Everything was in full view while standing on your head looking up under the dash.
For the benefit of other "chumps" like myself, who might have this problem in the future, I grabbed the camera and took the attached pics.
No. 1 Shows the connector detached with the far right position fried.
No. 2 Shows the connector socket in the resistor block with the far right position fried.
No. 3 Is the view under the passenger side dash panel showing most components, i.e. the blower resistor block, the connector attached to the wiring harness, and the blower motor in view.
Do I have these parts identified correctly? I think so.
The last loose end is this:
Per your advice, I won't cheap out and will buy new parts and install. But what causeded this burnout in the first place? If I install the new $100.00 plus parts, will it just happen again soon?
How about some advice as to how this "burnout" occured without fuses protecting the circuit?
Should the motor be checked for excessive current draw.
This may be windy, but it may help the next guy.
I really appreciate the help on this.
Best Regards,

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RE: AC fan motor problem
 

Bump

RE: AC fan motor problem
 

I've seen 1 truck repeat...from excess draw from the fan...most I believe are just inferior resistors...A new gm resistor will be of a different design,usually.
The blower fuse is a 40 amp maxi fuse...apparently,thats too much for the circuit.its in the underhood fuse box

RE: AC fan motor problem
 

would down-sizing the fuse to, say, 30 amp help preserve the resistor block? or switching fuse type? (not sure if that is possible) (my resistor block croaked at 90,000 a couple of weeks ago)

RE: AC fan motor problem
 

I guess..they use slow-burn fuses...however,I've never seen the new design resistor ****can

RE: AC fan motor problem
 

Hey Argon:
Thanks for the input on this problem. Could you comment on about when the "new design resistors" came into being. My truck is a 2005 produced in Aug. 04 with recently failed resistors.

And, did my pics show the right parts?

Regards,