99 suburban HVAC controller frying

I am new to the site I have a 99 suburban k1500 in which I have replaced the AC compressor condenser accumulator metering device and lines I have replace the lines with single cab lines pulled vacuum and charged (I am a HVAC technician by trade)


When I start the AC it will run for about 10-15 seconds and then will smoke the HVAC controller blew two of them so far the original and a replacement

Found a wiring diagram of the AC says there's supposed to be a diode between the clutch signal and ground to the compressor and I'm not seeing one on my harness

I'm leaning toward the diode is not blocking the signal back clutch shuts off and back feeds to controller?

Anyone have this issue before

I have also replaced blower motor and resistor

When the controller is good the light will be on the the AC button

When it smokes it will only run at the feet setting for air and no light to the AC switch is on

Another thing I forgot to mention is I have 12 volts to power into controller harness with vehicle not running 14v when it is so it's not the alternator in my opinion

I haven't heard/read anything about a diode in the harness, but I do know that the '95-99 HVAC control switches are notorious for failing. We had to replace 3 on the previous 99 Burb before we got a good one, and Dad was buying Delco ones. Also this was 15+ years ago before the current problems getting good new parts....
I still have the good switch panel that we took out of that Burb after it got totaled. It's going into the current Burb....