94 Blazer AC Mystery From Hell!

[TBaganATX]

Ok.. so I'm having issues with my AC in my 94 Blazer. Now realizing there are multiple resistors for w/ AC 3 & 4 speed and w/o AC. I have bought all new relays, changed 1 got the other 4 the other day. I changed the resistor, now realizing that it is for a W/O AC, so I ordered a 4 speed AC, plan on changing this weekend. The 2 are a lil different on has 2 prongs and 3 prongs. The new one has 3 prongs and 2 nubs. I'm guessing the 2 wire will some how connect to the nubs? Also, noticing that my AC speed switch will go 3 speeds and barley puts out air, even on high. Now when I can get it to switch from low/med and med/high the air really starts blowing much harder, then switch to High and blows as it should. Or I can hit a bump and it will switch back and forth or it will just completely, shut off. There is either a short or something I'm missing. Anyone have any suggestions?

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[mtl111]

My only experience with the older style hvac controls are with my Dad's 88' GMC C1500 that unfortunately was totaled by some lady in a Camry. That system always worked fine but it sounds like you may be having issues with the hvac control itself. It may be getting tired and not actually doing what is indicated, especially since it fails when you hit a hard bump. I would check it out and verify it's working correctly. Good luck, keep us posted.

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[wjburken]

@UmmScott

 

[OR VietVet]

Hope it isn't this. $125.79 plus $200 core at RA and is currently out of stock and looks to be a reman: https://www.rockauto.com/en/moreinfo.php?pk=9451016&cc=1050725&jsn=4599

 

[UmmScott]

Sounds like that control head to me.

I would check your powers and grounds thoroughly especially grounds before going further.

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