Air conditioning troubleshooting

[firemedicsafd]

Is there a how to or YT video on diagnosing a/c system issues. 88K5 blazer with stock A/C system. Mine will not turn on at all. I know I don't have a/c itself because the components aren't assembled in the engine bay, but the heater should work. But it does not. Fan will not come on at all when it used to. The sliders work fine inside but nothing happens. Thank you for your help!

 

[88Silverado]

Assume you verified fuse is good. I had a similar problem where the fan just stopped working one day. I checked fuse and the fan first with a 12V source at the fan ternimal. Finally found the circuit traces on the slide controller assembly were burned open. Replaced it with one from LMC. Later had some issues with intermittent fan speed setting and I replaced the resistor bank in the blower box and all's well.

Good luck

 

[6872xtc]

There's the fuse, the resistor pack, and the relay on the evaporator housing, (under the hood, by the blower motor) and, I believe the switch on the top of the control panel, in the dash, to operate the blower motor.
After checking the fuse, I would jump to the blower motor, check for proper ground, and then jump power to the blade terminal for the motor. This would tell if the motor is bad or not, or lacking a ground path.
If it works, then verify that there is no power at all, into or out of the relay, which is right there. Could be as simple as bad connections at the motor or relay.