[Timritchieblue]

Update..I was driving truck to my toolbox , transmission started acting weird?? Parked, and trailers to shop. WAITING FOR Diagnosis.
Im learning learning lil by little..scared OB2, nothing,

Hp tuners is incorporated into the trucks PCM. So hopefully we can track the Transmission problem. Then I’ll return to A/C.

 

[n9cv]

Back on Mar 9th I posted in this because of your comment of when I press the AC button the light will not turn on. I hope you saw it, but you just never replied. That light is turned on ONLY when the fan is in position one or higher,,. NOT in the lowest OFF position. The light is controlled right there in the HVAC module by the blower switch along with the AC switch . To turn it off, the lead from the fan switch off position to the logic portion of the HVAC module is grounded (-12 volts DC). The absence of the light on tells me that either the bulb is bad, you have the fan switch in the off position, the blower motor switch is bad (probably shorted) or that lead is grounded by the HVAC control module.

The lead leaves the blower switch on pin A of the HVAC module, and runs on a dark green wire that returns to the logic portion of the HVAC module on PIN 7 labeled on the schematic "OFF BLW MTR CONTROL". With that line grounded, the HVAC module is never going to tell the BCM to turn on the compressor.

So until you can get that light to turn on and off correctly, nothing else you check is going to work to fix your problem.

If you do end up replacing the module, be careful. I got one from an 06 to put in an 05 and they were different. I ended up robbing the switch out of the 06 module and putting it in the original 05 HVAC module.

Good Luck

 

[cart7881]

Just a note and it might not even be applicable in this case: If a fan speed is selected and the A/C is turned off, and the mode selector is turned to full defrost, the compressor will operate and the indicator light in the A/C switch will be off. 🙂

 

[Timritchieblue]

Back on Mar 9th I posted in this because of your comment of when I press the AC button the light will not turn on. I hope you saw it, but you just never replied. That light is turned on ONLY when the fan is in position one or higher,,. NOT in the lowest OFF position. The light is controlled right there in the HVAC module by the blower switch along with the AC switch . To turn it off, the lead from the fan switch off position to the logic portion of the HVAC module is grounded (-12 volts DC). The absence of the light on tells me that either the bulb is bad, you have the fan switch in the off position, the blower motor switch is bad (probably shorted) or that lead is grounded by the HVAC control module.

The lead leaves the blower switch on pin A of the HVAC module, and runs on a dark green wire that returns to the logic portion of the HVAC module on PIN 7 labeled on the schematic "OFF BLW MTR CONTROL". With that line grounded, the HVAC module is never going to tell the BCM to turn on the compressor.

So until you can get that light to turn on and off correctly, nothing else you check is going to work to fix your problem.

If you do end up replacing the module, be careful. I got one from an 06 to put in an 05 and they were different. I ended up robbing the switch out of the 06 module and putting it in the original 05 HVAC module.

Good Luck

I seen your comment, I went out to start testing, I have no light engagement switch on?? Doesn’t matter where the fan switch is on ??
I’m hoping to find out something on transmission. Need my truck back.

I got myself into a mess

 

[cart7881]

Update..I was driving truck to my toolbox , transmission started acting weird?? Parked, and trailers to shop. WAITING FOR Diagnosis.
Im learning learning lil by little..scared OB2, nothing,

Hp tuners is incorporated into the trucks PCM. So hopefully we can track the Transmission problem. Then I’ll return to A/C.

Regarding the A/C. I'm still not clear on how and when this issue started. From the first post I assume that the truck has a swapped engine. I also asume that when the truck was purchased, with the swapped engine, that the A/C was operating normally. Then, after you "cleaned up" some wiring, the A/C would not operate. Are those assumptions accurate? If so, are you convinced that something you "cleaned up" didn't contribute to the problem?