Fan wont blow on high.

[Schurkey]

it was the red wire right at the connection under the glove box. It melted the connector on the red wire. Just wondering what would cause this and how do I prevent this from happening again

Usualy caused by excessive current draw. Sometimes (rarely) caused by contaminated or damaged connector that has high resistance.

I would be checking the current (amperage) draw of the blower motor. If it's in spec, replace the damaged wiring and move on. If the amperage draw is too high, replace the damaged wiring, replace the blower motor, verify there's no excess debris lodged in the A/C evaporator or HVAC blower-box, and move on.

 

[351FUN]

Agreed, test lights have their place but anything like this I'm grabbing the fluke and seeing what the actual numbers are.

 

[bigcreepo]

hey do you by chance have a pert number or what kit did you get to replace it? im having the same problem and its melted them together. thanks in advance.

 

[Schurkey]

Similar melted 3-wire connector:

Repaired by using a single-wire Weatherpack connector in place of the damaged connection. The other two wires in the 3-wire connector still had good conductivity, and the connector without the big red wire fitted together OK, so I just put that connector back together.

 

[bigcreepo]

Similar melted 3-wire connector:

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Repaired by using a single-wire Weatherpack connector in place of the damaged connection. The other two wires in the 3-wire connector still had good conductivity, and the connector without the big red wire fitted together OK, so I just put that connector back together.

You must be registered for see images attach

the red one melted my connector so I have to replace it

 

[Schurkey]

Consider a 3-wire Weatherpack connector.

 

[bigcreepo]

hey guys happy weekend, so I replace the melted connector wire with new connections, tried the high but still nothing. I used my fluke tester and I only get continuity on the high setting. not 12volt. I don't have a test light just a fluke t-pro it can do both ac and dc. I checked every fuse and they are all ok, I can hear the relay turn on for the lower setting and click on the high setting. but I don't know if its the relay and that was gonna be my next move. its the original relay and was wondering if it could be that?

I read that the wire is a fuseable link too it that correct or is that wrong? anyhow any hvac blower experts that can help would be greatly appreciated. thanks in advance.

this is for my 1996 GMC Sierra c3500 single cab truck. 5.7 2x4

 

[east302]

Disconnect the relay connector and check for

*12V on orange with switch in high (confirms blower switch)
*12V on red at all times
*varied voltage on blue at lower fan speeds (confirms resistor and blower switch)

If that all checks out and you get no voltage at the purple blower wire with everything connected, then the relay would be suspect.

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[Schurkey]

I checked every fuse

Including the under-hood 50-amp "Blower Fuse 3" from post #4?

How about the 25 amp instrument panel "Htr-AC Fuse 12" from that same diagram?

its the original relay and was wondering if it could be that?

Sure. Test it and see. Or swap with another relay.

I read that the wire is a fuseable link too it that correct or is that wrong?

I see no fusible links in that diagram.

 

[bigcreepo]

Including the under-hood 50-amp "Blower Fuse 3" from post #4?

How about the 25 amp instrument panel "Htr-AC Fuse 12" from that same diagram?


Sure. Test it and see. Or swap with another relay.


I see no fusible links in that diagram.

I checked every fuse under the hood too. ill give it a second look tomorrow and thanks for the help! ill keep you posted on what I find.