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2005 Silverado Blower


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larry78
User

Jun 18, 2010, 8:14 PM

Post #1 of 9 (5898 views)
2005 Silverado Blower Sign In

Blower on 2005 Silverado does not run on any setting. When removed from truck, blower will run on 12 VDC power supply but seems to turn a bit stiffly and seems to draw a lot of current (wires get warm). 12 VDC power supply is rated at 2.5 amps and trips off after about a minute. Relay board seems funky. When I wiggle the connector with power on, the relay chatters. Voltage at blower connector is erratic (0-10V) on 5 and on setting 1-4 does not change (12V) Also one lead (black wire) in the connector block on the relay board shows signs of over heating. Fuse in underhood fuse block is not blown.

Should I replace both the blower motor and relay board?


Sidom
Veteran / Moderator
Sidom profile image

Jun 18, 2010, 9:10 PM

Post #2 of 9 (5886 views)
Re: 2005 Silverado Blower Sign In

There is actually 4 fuses for that system, blwr mtr 40a, heater a/c 30a & 2 hvac 10a fuses. If all the fuses are good an one wire shows signs of getting hot, it shoulds like the motor may be drawing too many amps. It's possible that on it's way out the motor took out the resistor with it.....

The motor gets it's power & ground thru the resistor. You can check both wires of the blower motor with a test light with the system on. If both have power, then the ground is bad. To test it you would be able to ground the black wire and the motor should come on.


larry78
User

Jun 19, 2010, 6:18 AM

Post #3 of 9 (5881 views)
Re: 2005 Silverado Blower Sign In

All 4 fuses were good. I am getting 12 V to ground off the black terminal with the fan switch on 5. Guess I will replace relay board and motor.

Thanks for the help.


Sidom
Veteran / Moderator
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Jun 19, 2010, 9:19 PM

Post #4 of 9 (5875 views)
Re: 2005 Silverado Blower Sign In

If all the fuses are good and you're getting 12v to the motor on high then it sure looks like the resistor is bad. Those did/do have a problem with the control heads but you said you're getting 12v coming thru the switch and going to the motor.

About the only other possibility would be a bad ground wire to the resistor (black wire). You could check that with your test light. Hook the clip to the batt + (or any good 12v source) then touch any good ground to make sure it lights up. Disconnect the connecter from the resistor & probe the black wire, if it lights up then you have a ground on that wire. Also make sure the terminal is in good shape & hasn't been overheat & is weak.........

It sounds like the fan motor is bad from what you've posted. To accurately test it you would have to measure how many amps it was pulling.

About the only other thing that could cause this heat problem would be excessive resistance in the ground circuit.. You could do a voltage drop test on the ground wire. Any drop over .3v would be too high & could cause some problems.......


larry78
User

Jun 20, 2010, 7:17 AM

Post #5 of 9 (5865 views)
Re: 2005 Silverado Blower Sign In

I got a new motor. NAPA did not have the right resistor (2 form factors, go figure) but I "borrowed" the wrong one for a test. When I bench tested the motor, it seemed to pull way less current. At least it did not trip the breaker on my little 12 VDC power supply. When I connected the new (wrong form factor) resistor the blower worked on all 5 settings....problem solved.

So, bottom line, when I get the right resistor (on order) it will be fixed.

Thanks for your help!

Larry


Hammer Time
Ultimate Carjunky / Moderator
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Jun 20, 2010, 7:44 AM

Post #6 of 9 (5860 views)
Re: 2005 Silverado Blower Sign In

Gold star for Sidom.................. Well done






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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Jun 20, 2010, 7:45 AM)


larry78
User

Jun 20, 2010, 7:49 AM

Post #7 of 9 (5856 views)
Re: 2005 Silverado Blower Sign In

Just saw a GM service bulletin on this problem. Apparently the connector was underdesigned, causing the heating problem. They recommend replacing the connector on the harness side as well so...one more part to order.

More info for your file!

http://www.motorcity1.com/TSB_Heater.htm

Thanks,

Larry


(This post was edited by larry78 on Jun 20, 2010, 7:55 AM)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 20, 2010, 8:00 AM

Post #8 of 9 (5851 views)
Re: 2005 Silverado Blower Sign In

Yes, you should always check the plug for any signs of overheating. That's a common problem in many different blower circuits.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Sidom
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Sidom profile image

Jun 20, 2010, 4:14 PM

Post #9 of 9 (5845 views)
Re: 2005 Silverado Blower Sign In

Glad to hear ya got it going (or gonna get it going) Larry..... Thx 4 letting us know the outcome...

Good catch on the connecter.

GM reallly seems to have problems with their connecters.... Seems like almost everything has a new connecter for it....Crazy






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