Need help diagnosing blower motor problems.

[spinachrat]

I'm getting wrapped around the axle trying to figure out why my blower motor is not working. I replaced the blower motor and resistor 2 months ago. It recently stopped working completely so I started poking around. When the 12v terminal on the motor is jumped, nothing. When the ground terminal is jumped to ground it works fine on all speeds except high. It seems that the ground wire is bad but I can't figure out where that wire goes. There is continuity between that wire and the orange wire (which dead ends at that connector) on the connector for the HVAC control panel. Anybody have any tips on what to try next?

1995 K2500 6.5

 

[HotWheelsBurban]

I've heard that the '95 trucks use a one year only HVAC switch panel in the dashboard. That said, I have had blower issues with both my 99 Burbs. The other one went through three switches in a few months, and I ended up replacing the resistor and the motor too. My current Burb has a similar situation,and I just haven't had a chance to diagnose it. But I'm 90% sure it's the switch; it often is on these trucks.

 

[spinachrat]

I just ordered a 96+ switch and I'm going to make my own adapter wire harness. We'll see how it goes...

 

[bretcopsey]

I just ordered a 96+ switch and I'm going to make my own adapter wire harness. We'll see how it goes...

I have a 95 also and literally just finished up refreshing my dash. The HVAC switch is dated 2002 and had the adapter harness so I snapped a few pictures knowing these are an oddball configuration. Hope these help you out with making your own harness!

 

[east302]

The GM manual can be downloaded here…

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

From that, here is the diagram for a 95. With ignition on, switch on high, do you get voltage at the blower (purple wire)? It looks to use only one ground for all speeds (G106) which is on the back of the right cylinder head. Seems like you’d have other issues as I’d think other systems use that ground.

Pull the connector at the blower relay (should be next to the resistor) and see if you have voltage on orange (52) at the connector with it selected on high and jumping it to black. Ignition on, do you have battery voltage at the connector on red (542)?

Best guess…your connector at your blower switch is melted and causing a bad connection to the blower switch. For 96-98, these are the replacement but I’m unsure if 95 is the same.

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[someotherguy]

Pretty much in order:

Blower motors go bad (no fan at all)
Blower motor resistors go bad (fails on all BUT high speed)
Ground and power connection to blower motors go bad (no fan at all)
Fan switch and harness connector go bad (random speeds go bad)

The 1995 model is a one-year-only design and 1996-up controls are substituted with an adapter harness, though the fan switch itself is a separate component and usually the control unit is not the failure point for blower fan issues.

The fan switch and harness pigtail are available separately.

Really not difficult to diagnose with a simple test light.

Richard

 

[spinachrat]

I made my adapter harness (with much help from a great YouTube video) and the blower motor now works as it should when the ground terminal on the motor is jumped. I guess my ground is bad somewhere.