98 Chevy Venture HVAC blower adventure

My wife's car. The blower stopped blowing on setting 5 last year. Then it lost 3 a few months ago. Then 1. Then 2. Then 4 finally died. No blower. No front defrost. This is the Northeast. Autumn in the Northeast. Not recommended.

So I dove into it today. Without a manual... As Chris would say, I nuked it out. The blower is located at the front passenger's feet. It's easy to get to; there's a carpeted cardboard cover with several of those plastic 'pop' fasteners. A quick tug at the front ad it comes off. The courtesy light comes out after a quarter turn.

The normal cause of failure for these things is the resistor block. So I started looking for the resistor block. Of course, it's behind the motor, next to the firewall. Lovely. It turns out to be pretty easy to remove the blower. There's a two-wire connector. Push the top (it's one of thos prong types) and pull it out. Remove the 2 screws and the blower motor and squirrel cage comes out. It took a bit of twisting.

Now I can clearly see the resistor block. It has 3 screws, one of which is almost impossible to get out. Loosen the two nearest the firewall about 1-2 turns, then remove the one closest to the passenger's feet. Pull it down, toward the floor and then it should tip enough to pull it off the two screws toward you. Pull the black connector off and you're good to go.

So now I have in my hand one 12v squirrel cage and one resistor block. It occurs to me that I have a cellar full of 12v power supplies, so I go down to the lab to check it out. I hook up a 12v current limited supply and turn it on. It works! Very nice... the fan turn and churns. Well at least that's one thing that I don't have to buy.

I spent about a half hour trying to figure the pinout for the resistor block, but it remains a mystery. I couldn't tell if it was bad or good. So I turned my attention to the connector in the car. I tested every combination of voltage and continuity vs switch position and got nothing.

Nothing?

Is the switch bad? Feh. Time to burrow into the dash.

This turned out to be simple! Pull the ash tray out and you'll see a screw on the right side. There's a mate on the left under the power socket cover. Remove them and the console frame pulls out from the bottom. It becomes obvious what to remove next. All the switches are mounted to a single carrier. Two more screws and it comes out, revealing the blower switch.

Pulled the connector off of that and I see a burnt socket, with a burnt pin matching it in the switch. Hm. Turn on the key so the system is energised. I test the socket and find 12v in the middle of the 3 side. Short that to the socket opposite it on the 4 side and probe the other end - voltage! Crap, the switch is looking bad.

Lay the blower on the floor, hook up the resistor block (on the floor) and connect it. Short out the two sockets and the fan spins. Yep. Bad switch. So I put the resistor block back, put the blower back, put the courtesy light back, put the cardboard back. Short together the 12v side of the connector with the pin for speed 3, turn on the key and voila! Always on, but it won't leave the wife stranded without a blower. Electrical tape for safety and put the console back together sans switch.

Tomorrow I'll get a new switch. It should take less than 15 minutes to install.