HVAC controls testing

[billbob1936]

Hello. I'm looking for help testing out my HVAC controls. I noticed my AC hoses freezing over, and sure enough, the blower was no longer working. I've tested the blower and it works fine with 12 volts supplied to it from under the hood. I have 12 volts at the light green wire feeding the controls, but no voltage output on any of the tri-wire connections regardless of Heat/Cold switch setting and/or fan position. Same goes for continuity testing on the removed unit. The blue wire/AC output on the controls does turn on with the AC switches pushed to the on position, so it appears that at least some power is entering the device. Would someone know the power output expectations on the terminals. Also, does this device have a history of failure? Thanks.

 

[Challenger RTA]

Accessory wiring. start with the fan sw. The single terminal on the fan sw is the power. Connect one lead there. Test the other two in terminals see of you have continuity. If not bad.

 

[billbob1936]

Accessory wiring. start with the fan sw. The single terminal on the fan sw is the power. Connect one lead there. Test the other two in terminals see of you have continuity. If not bad.
View attachment 129217View attachment 129215

Thanks. I'll save that diagram for future issues. Turns out, the fuse (that appears to be normal) was the culprit. It is slightly warped behind the glass, so it must be internally pulled away from the metal end-point. I guess that's better than replacing a $200 control unit. Lol Thanks again for the response!