a/c selector switch

[LANIAC]

does the main feed from the fuse block run through the selector switch. so if it were bad would that cause a malfunction to the relay ,resistor and blower mtr. ,getting hot with a test light at relay and selector switch but no hot after each one

 

[animal]

@chengny is one of the wiring guru's

 

[gmachinz]

No. There is a 14ga brown wire which supplies power tonthe selector switch. From there you have low and medium leads (yellow and light blue iirc) which go through the resistor board and through a closed set of contact at the blower relay before going to the motor via the purple wire. High speed bypasses the resistors and runs full blower power off the battery direct as in from the +12V common junction block.

 

[animal]

My apologies @gmachinz . I always think of you for the wiring kits and such, but spaced out and did not think about you here. Thanks for the reply

 

[LANIAC]

blower motor doesn't work, checked blower mtr and its good, checked the hot wire coming from junction block and it lights at the relay bolted to a/c box. shouldn't the purple wire light up after the relay

 

[animal]

I had an issue when I bought my truck with my blower motor. Took the motor out and hooked it to the battery. Worked fine, put it back in, no worky. I thought I had a wiring problem. Bought a new motor and put it in and it worked.Old Motor was going bad but it still checked "OK"

 

[LANIAC]

i'll try a new one, but shouldn't the purple wire running from the relay to the blower mtr light up, or does it mean the resistor is bad, or possibly the relay

 

[gmachinz]

Make sure that ground wire going to the blower motor case is really tight. And the red is always hot at the relay since it comes from the battery junction. The AC blower relay is really just an old school version of what we know of as a 5-pin Bosch style relay. Purple to blower is 30, med and low speeds are in series through 87a, red wire is 87, green is 86, a switched hot while black would be an 85.

Make sure too that the black wire on that blower relay is properly grounded with no breaks anywhere-it grounds to the blower motor case and from there to the chassis.

 

[LANIAC]

Thanks guys i appreciate all the info, turns out that the selector switch was getting a bad connection, i hope to posts some pics of my truck soon