No HI Blower Speed

[SmittySS]

Howdy!
My 96 Suburban does not have High Blower, it hasn't since I bought the truck.
When the other speeds stopped working this past winter, I replaced the resistor as well as the blower motor. I installed the new blower because the original blower had a terrible squeak.
However, with the new parts installed it still did not have HI.
Using a test light, I determined that there is power from the control head to the relay, but there is no voltage supplied to the relay when it is activated.
The 50 amp fuse under the hood is good.
Is there a place where this wire, from the under hood fuse box to the connector under the dash, commonly fails?
Look forward to hearing from anyone with info, or links!

Smitty

 

[Dr.Zoom]

Bad switch? Not sure about your question about a common failure point though. Can you test that the relay is getting power from the switch? Should be pretty straight forward to find where you aren't getting power and then solve that.

 

[SmittySS]

I'm wondering if there is a common fail point for the wire that comes from the 50 amp fuse to the HI blower relay.

My switch is working properly, there is no power on the RED wire at the relay. This power should be supplied by the 50 amp fuse in the under hood fuse box, and the fuse is good.

If this is a known common fail, it would be great to go directly to the point in the wire that is broken and fix it, rather then chasing the break in the wire down myself.
I will likely just run an new wire from the fuse box to the relay to solve the problem.

Smitty

 

[1999gmc]

Have you checked to make sure the pin in the bottom of the fuse box has not pushed out that goes to the blower motor? Mitchell says there is a splice by the ECBM where the red wire from 50 amp fuse splices and goes to other stuff. I had that on a Tahoe. The wire popped out of the bottom of the fuse box connector, so when you check the fuse the busbar was suppling voltage but the wire going to the accessories wasn't connected to the other side of the fuse.

 

[SmittySS]

I discovered where the connection was lost for the HI blowers power.
I knew the wire ran across the engine compartment thought the engine harness, so I broke the loom open at the most convenient spot closest to the under hood fuse box, to see if the wire had 12 volts at that point. It did not!

I decided to cut the wire there. I verified with a jumper wire that it would in fact power the HI blowers, which it did.
I opened the harness in the small section from that point to the fuse box... lo and behold, there is a junction point there which had rotted away. Where two of the three wires were still connected, the taped connection was actually hot to the touch. This junction off of the 50 amp fuse apparently goes into the vehicle at the "convenience center."

Attached are a couple of pics of what I found, one of the broken junction, and another to show perspective of the location.

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[Dr.Zoom]

It's hard to see what's going on there. Was it a connector? Just looks like sort of a "stump". Good find!

 

[SmittySS]

You are exactly correct!
It's just a stump. Originally was three wires soldered together and wrapped with tape.
The third wire was the one that came disconnected, leading to the HI blower relay.

Smitty