The #4 position on my blower dial stopped working. I've replaced both the resistor and the dash module and still #4, doesn't work.

 

Not sure what you're working on. In the 98+ 2nd gens with manual HVAC controls where #4 is the highest setting, the fan will be powered through the HVAC fuse in the underhood fuse block. The fused power runs through the blower motor relay as well which should be located up on the firewall above the HVAC housing somewhere near where the blower motor resistor is located under the hood on the passenger side.

 

2000 Blazer 2dr 4x4

 

This

Not to be confused with the blower motor resistor, this is literally a relay that's bolted with a single bolt to the firewall.

Very common for the relay to give up. I'm guessing because it sits right above the engine and just cooks in the heat, but that's only a hypothesis of mine...

 

Thank you. I picked one up. Tomorrow I'll see if it's the fix.

 

Replaced the blower a few months ago, the resistor last and the climate control module last week and the relay today. Still no power to #4. I did my best to check the wires on the resistor and they seem to all have current. What's left?

 

Fuse or wiring.

 

How many fuses are on a 2000 Blazer in regards to the fan speed? What I found seemed fine.

 

As I stated, the HVAC fuse in the underhood fuse box feeds +12v power to the blower motor relay.

About the only other thing it could be is the blower motor relay not being commanded to switch to full +12v power from the HVAC fuse.

You will have to do some testing at the relay to see what is going on. When I get home I can see if I can get a wiring diagram for you. Can't do that too well from my phone.

 

I have a "Chilton's", or the like. But any help is appreciated. Thank you.