hey yall, im new here so please forgive me if this question has been answered.
I picked up a 1999 blazer from auction a week ago and ive been fixing some misc issues with it. 1 issue that im having a hard time fixing is the AC/heat. When i turn the **** to turn on my ac/heat nothing happens, like 0 air is comming out, blower motor not kicking on, and ac clutch not engaging. I tried obvious stuff like fuses and relays but nothing. I also changed a couple leaking vacuum lines cause i know the ac is vacuum operated and nothing again. i switched out the climate control panel with a junk yard replacment and nothing (the junnk yard replacment might also be inop). Here is what i can tell yall, when i go switch the ac on i can hear vacuum air noises (idk best way to describe it lol) but nothing comes on. what should i try next? thanks everyone!!!

 

I'd get that fan working first. When I had trouble getting all 4 fan speeds, this fixed me up: Dorman 973-005 HVAC Blower Motor Resistor Compatible with Select Chevrolet / GMC / Oldsmobile Models. On a 2002 chevy blazer screws are tucked away, need a small ratchet, like 1/4"

 

I believe there is a pressure switch on the AC system that might prevent the compressor pump from activating, but I'm not sure.

Do you know if the system has refrigerant in it?

If you decide to go with a full AC system rebuild, I have a writeup about doing that on my build thread.

 

It sounds like you need to chase the power first. Do you get power to the proper wire at the control switch?

 

So you get no blower fan on any speed and the compressor clutch never engages?


George

 

Yes sir that's correct. The bearing is spinning freely but it's not engaging. The blower motor doesn't kick on aswell. The rear defrost button is illuminated so I know the panel is getting power.

 

By bearing do you mean the ac compressor clutch? Are you sure it never engages intermittently?

Have you looked at the system pressures?

Is it manual or automatic AC?

George

 

I don't think that anything about the A/C system would stop the heater (HVAC actually) fan from working.

 

Do you have Electronic /Computer Climate Control or
Manual controls?
Difference is blower motor with manual controls has 5 position switch to control blower speed using blower resistor.
Electronic / Computer control has automatic / variable speed control, blower speed is controlled by solid state controller. mounted on firewall close to blower motor. Blower motors are not interchangeable.
If you have manual controls testing blower is easy. If your not 100% comfortable working with electrical circuits safely and use safe procedures, do not test. Im offering advice only, use at your own risk!
1. Check fuse, Ignition in Run position, put blower in high speed position. Blower should run. High speed bypasses the resistor unit. If blower runs only in high then you have defective resistor, blower switch or wiring.
2. If blower not running. Check blower motor relay located on firewall. Jump Orange? and Purple? (colors may vary) wires to check relay.
3. If still not working. Jump between battery and blower motor.
4. Verify ground between blower and ground and re-test, if not running you need new blower motor.
5. If blower runs you have: Bad blower switch, relay or terminals. Less likely is wiring, however vehicle's have had multiple owners and could have wiring modified / cut or age related failure.
Wiring schematic attached