04 Suburban Z71 heater fan headache - The 1947 - Present Chevrolet & GMC Truck Message Board Network

rickpilgrim · 03-03-2015, 03:14 AM

Our 04 sub Z71 with auto temp has the front heater fan on high all the time even when shut off. Also sometimes the display blanks out or the 2 temp knobs don't change the temp. O Reilly's cannot seem to find a relay anywhere on their diagram and it all worked a day ago and this morning it acted up.I know it's something simple, just would be nice to not pull fuse on shutdown and re install on startups. Ideas what to replace anyone?

Mr-Jack · 03-03-2015, 12:12 PM

start shooting wires...you might have something shorted to ground. did you get a copy of the wiring diagram from the part's store.

4x4toy · 03-09-2015, 05:27 AM

You need a blower motor control module. It is next to the blower motor under passenger side dash. Newer GM vehicles have pulse with modulated fans to control speed, no longer use blower resistors. Buy a GM replacement, stay away from aftermarket. If it does have the resistor style fan control it will have a relay built in and that may get stuck and have the fan blow high all the time. 2004 could have either one.

rickpilgrim · 03-09-2015, 12:14 PM

Our 2004 Z71 has the blower control module with the built in resistor. I replaced it with $100 aftermarket one allready in there and will get the GM one when that acts up.
Thanks for the help.

03-03-2015, 03:14 AM	#1
rickpilgrim Registered User Join Date: Apr 2011 Location: Wausau, WI Posts: 591	04 Suburban Z71 heater fan headache Our 04 sub Z71 with auto temp has the front heater fan on high all the time even when shut off. Also sometimes the display blanks out or the 2 temp knobs don't change the temp. O Reilly's cannot seem to find a relay anywhere on their diagram and it all worked a day ago and this morning it acted up.I know it's something simple, just would be nice to not pull fuse on shutdown and re install on startups. Ideas what to replace anyone?

03-03-2015, 12:12 PM	#2
Mr-Jack Beer Drink'n Knuckle Dragger Join Date: Mar 2010 Location: Eatonville, WA Posts: 493	Re: 04 Suburban Z71 heater fan headache start shooting wires...you might have something shorted to ground. did you get a copy of the wiring diagram from the part's store. __________________ GOD BLESS MY BROTHERS & SISTERS THAT SERVE WITH US *- 67 GMC Long-Wide* *350/SM420* *My BACON Wrapped Meatloaf Recipe*

03-09-2015, 05:27 AM	#3
4x4toy Registered User Join Date: Jan 2009 Location: Southern Md Posts: 228	Re: 04 Suburban Z71 heater fan headache You need a blower motor control module. It is next to the blower motor under passenger side dash. Newer GM vehicles have pulse with modulated fans to control speed, no longer use blower resistors. Buy a GM replacement, stay away from aftermarket. If it does have the resistor style fan control it will have a relay built in and that may get stuck and have the fan blow high all the time. 2004 could have either one. __________________ 04 Yukon XL 2500 w/ Quadrasteer 61 Chevy C60, 261 inline six 86 Chevy C20 2wd, Banks 6.2 05 GMC Sierra 2500hd Duramax

03-09-2015, 12:14 PM	#4
rickpilgrim Registered User Join Date: Apr 2011 Location: Wausau, WI Posts: 591	Re: 04 Suburban Z71 heater fan headache Our 2004 Z71 has the blower control module with the built in resistor. I replaced it with $100 aftermarket one allready in there and will get the GM one when that acts up. Thanks for the help.

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