I van has vents in the back but I could never get them to blow. I figured it must be related to this mystery knob to the left of the steering wheel that apparently didnt do anything when you turned it.

I started my troubleshooting back at the rear heating and air conditinoing unit. This thing is pretty slick. It has engine coolant hoses run to it as well as ac compressed gas lines. The wiiring is pretty simple. Its a 4 pin molex connector. I didn't have a wiring diagram but I knew at least one of them had to be +12. I checked every one of them and no 12v.

That means the problem is further up stream. I checked every fuse in the fan (and replaced 3 blown ones) but still the rear ac did not get power. The problem had to be that switch.

I pulled out the dash to get to the switch, then tested it switch. Sure enough, there was no combination of switch turns that allows flow down the leads. The switch was internally busted. I connected the wires manually one set at a time to test the rear blower. Thank God. It works fine. The mystery rotary switch is a blower motor speed controller. The three output wires are for low, medium, and high speed. All work as they should.

This means that the driver can control the rear blower motor speed using the rotary switch, but how does he control the temperature. Well there is a 5th wire going into the bottom of the heat / ac unit. My theory is this 5h wire is hot when the AC is on, and off when the AC is off. In this way, the rear passengers get low, medium, or high air flow of full heat, or full ac, with no middle ground.

Its not as snazzy as newer systems that allow rear passengers to control the temperature too, but it sure will be nice to have it working again. I wonder how long that faulty switch has disabled the system. I have ordered a replacement switch for $5. Should take of the issue right away.

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Smll Med Lrg	Smll Med Lrg Acme unit, no model number anywhere, go figure	Smll Med Lrg	Smll Med Lrg climate control never lit up at night
Smll Med Lrg	Smll Med Lrg turned out bulb had fallen out	Smll Med Lrg	Smll Med Lrg I reinstalled it with a dab of super glue to hold it in place
Smll Med Lrg factory wire harness for rear blower motor controls. I wonder by con van co. didnt use these wires	Smll Med Lrg	Smll Med Lrg	Smll Med Lrg
Smll Med Lrg old dash had glue residue all over it from old fake wood sticker	Smll Med Lrg old dash was also cracked.	Smll Med Lrg rather than spend hours cleaning old dash I just got another one off ebay, much easier and cheap	Smll Med Lrg also picked up replacement switch, works like a charm
Smll Med Lrg Nikki cleaned up the old plate and recolored the text	Smll Med Lrg new switch, new looking plate, and old knob installed on new dash	Smll Med Lrg i liked the all wood look from before, but it was in bad shape. This looks much better