WAY OT '92 Deville climate control fan

I need some help from you guys. I bought a 92 Deville back this summer. When I bought it, everything worked other then the trunk pull down motor. The cruise, air, windows, seats and everything worked. About a month ago the CC fan quite working so today I did a little investigating to find out how to fix it. I unplugged the 2 prong wire harness from the fan with the CC on defrost and high fan. I had one of those little test lights and put one end on the battery neg and the other on either prong of the harness end. Nothing lit up on either prong. Then I put the test light on the battery pos and on each harness prong. On the black prong, the tester lit up bright and the purple prong it lit up abour half brightness. Then I put the CC to auto and tested things again. The black prong lit up about half brightness and the purple prong did not light at all.
I am really confused because the way I understand it, one of the prong should have lit with the test light on the batt negative. I have heard that on this model the CC has a tendency to go out and is not available new. I am trying to figure out if the CC has gone bad or if it just a fan issue. I used to have a Seville and it burned out the fan last winter so i am hoping this is similiar but at $100, I want to make sure it is a fan issue and not a fried Climate Control unit.

You already know this, but remember that the engine has to come to temp before that fan can run.

Maybe a bad ECM temp sender?

Allan

really? I didn't know that. It would work this summer on a 60 degree morning, first thing when the car was started. Does that make sense?

Yeah,

It's been too many years ol' Pard.

Can't remember the specs, but that dude will not turn a wheel if the combination ambient/engine temp is below a certain thresh-hold. They do that so that the heater is not blowin' cold air on ya.

Forty degrees kind of rings a bell, but like I say it's just been too many years ago that I had to work on those jokers.

Allan

ok, thanks Allen, wasn't aware of that. learn something new everyday.

other than Allens ideas, the only other idea i can give you is to try the Caddilac Forum , I learned a lot from those guys ,and thats how i stumbled across this forum ... I owned a 94 Northstar some 5 yrs back , that car had AMAZING sterio radio , nice SCAT-POWER , and 20-26 mpg . ..BUT needed new heads at 215K, yucky paint, had way too much TUPPERWARE hanging off it ..terribly uncomfortable after a hundred miles and , I am Sorry to tell you , it was the worst car I ever owned ,only exceeded by a Cutlass , and a GranPriCK,.. on the otherhand every Ford truck or Crown Vic or Marqius I ever owned is still out there doing the job...

Your blower motor control module is almost certainly fried.Almost always fails due to a blower motor drawing too much amperage,so install a NEW motor regardless.

The module is located where the blower resistor would normally be which is under hood on top of HVAC evaporator case and held on with 2 screws.

Replaced a TON of these back in the day at the dealer.