On my 1994 S-10 Blazer, the AC/Heater stopped blowing on high speed about 2 years ago. By switching the speed control quickly back and forth, sometimes High would work. But not anymore. I had the A/C compressor replaced 2 weeks ago and settings 1-3 still worked, but still no High setting. Now, it only blows on Low no matter what the control is set on.

I replaced the blower motor resistor assembly (attached to the blower motor housing) AND the blower motor relay (5 pin relay attached to the back fire wall) and still no change.

The only other guesses that I have at this point are replacing either the inside Control Panel Assembly or the Blower Motor itself. Any suggestions would be greatly appreciated.

Also (unrelated), I need to find a digital instrument cluster for this thing. I've been without it for nearly 4 years now and can't find one at any of the salvage yards around here.

 

Going to try to find a front panel control assembly at a salvage yard today. Hoping that will solve my problem.

 

Ok....so I when I got back from the salvage yard, I installed a front panel control assembly that I pulled off of a wreck. Guess what....still no change. So now I think is HAS to be the blower itself. Right?

Can anyone tell me if there is a way to check the blower motor by "hot wiring" it between full on and off? I would hate to spend even more $$$ to get a new blower and that not do anything either. Any suggestions?

 

If the relay were bad, it could cause no power at all to make it to the blower motor.

Have a look at the schematic below:

 

Thanks for the schematic! I finally broke down and bought a Hayne's Repair Manual to learn some things that I can't figure out on my own. But here is the latest on my AC issue:

When I pulled the replaced front panel back off, I realized that the connector at the top (fan speed selector) was slightly melted between 2 connectors. When I ohmed out the switch itself, I found that it just changes which wires (1,2,3,4) get connected to ground. (For example, 1 and 3 grounded might be speed #2.) Then I realized that pins 3 and 4 were shorted together, essentially creating a "hard-wired" situation that wouldn't matter what the selector switch was set on. "Ah, ha!" I thought. If these were shorted together, then that would keep High from working even if the new relay that I got was working properly! When I put the panel back together without the pins shorted together, speeds 1, 2, and 3 worked just as they are supposed to....and still no High speed 4.

So I went back to my local parts store and bought the Blower Motor Relay (again) and installed it once more. Success! All speeds now work and I can stay cool driving around under the intense Florida sun! XD

 

Congrats on getting it fixed. Its always nice to hear success stories.

 

I just searched this thread and found it very helpful. Your misfortune in all of this was helpful to me lol. So thanks for writing up on everything you did. My problem is just the blower motor im thinking. My a/c has just not been blowing as hard as it used to. I replaced the resistor and the wires are good on the back of the panel switch. Did your blower motor ever make any noises when it wasnt blowing hard?

 

So glad that it helped you out!
I've owned 3 blazers (86, 94, 98) and I've never had a noise from the blower motor before. So I think you may be on to something in thinking that it's the blower itself. When I was thinking of replacing my motor, the salvage yards here wanted $40 for the motor.

Good luck in your diagnosis! Come back and let us know fixes it.