My '98 Blazer HVAC blower will not operate on high speed. A while back, it would work only on high, so I replaced the resistor. All was well for about a month. Then, I lost the high speed, but 1,2, &3 work fine. I replaced the relay which did not help. Then, I replaced the blower switch, which also did not help. The relay clicks when turned on "4", but no blower. There is only one hot wire in the 5-wire harness when on high, and that is the one that kisks in the relay. Based on past expereince with relay-controlled devices, should there not be another hot wire in the harness? I also found 2 fuses marked AC or HVAC and both tested good. Any ideas???

 

I was just about to post about this, My A/C blower only works on 4. levels 1,2,3 do not work at all. what do i need to do?

 

You need a resistor. My blower motor was binding up and blew 2 resistors, (had only highest speed) so you might have to replace it as well. Try a new resistor and if it goes bad, replace the motor.

 

Yeah fan relay.
Had the same problem on a e46 bmw worked on high only replaced the relay and worked like a charm should be under the dash somewhere. Common problem for a lot of cars!

2000 blazer 4.3l 4x4

 

There should be two wires at the relay that are hot when on HI. The Red wire which runs straight from the junction block and supplies the power for the blower to run and an Orange wire that is supplying power to actuate the relay. It really sounds like you have a bad relay or a blown Heater/AC fuse (25 amo). The blower on HI runs off a different circuit than the other fan speeds.

 

Is the 25A fuse in the panel on the left side of the dash or the one under the hood? I found 2 possible ones in the inside panel, but there might be one in the underhood panel.

 

Problem solved. Blown fuse in the under hood panel. I found 2 other fuses in the panel on the left side of the dash which checked good. Thought that was all of them. Oh well.......I will know next time! Thanks for the help!


B*B

 

Hey BB, glad to hear your problem was an easy fix. Mine however was not. I bought a new resistor, located it and replaced it, hoped back in the blaze, and still nothing! i was a little frusterated so i drove it up to Pep Boys to see if i could get any suggestions. All he told me was that he could run a diagnostic for $40, other than that he couldnt help me. Even more frusterated now, I went back out to the parking lot too see if i could run my own diagnostic (look to see if anything is visually out of place). I noticed that there was electrical tape on the plug that goes into the resistor. i decided to unwrap it and take a look. I thought maybe there was a short in the wire or something simple.

This is what i discovered:






the plug was literally taped to the wires! not connected at all!!!!
someone just taped it on there and called it a day!
UGH! i was SO pissed off yesterday.. I've calmed down a little bit since then though. lol

But what aggravates me is that i dont even think my resistor needed to be replaced, it didnt look fried. the resistors themself were a little discolored but does that mean it was fried? What do you think?
Close ups are attached.

OLD is on left and NEW is on right



So, I SHOULD be able to take a plug from the JY and wire it up to the existing wires correct?

The principle of the matter pissed me off...

 

Looks like somebody else had a problem and gave up. Get a replacement resistor plug and replace the plug. A good place to start. The resistor might not have been bad, but signs of heat makes it questionable. A new one is probably money well spent. Keep is posted........

 

Will do, not sure when i will be able to get a new plug but ill check out some places.