My Rube Goldbergish AC is back working..for those search impaired, this is a Sanden SD508 compressor direct driven by a 2 kW 24 volt DC motor. Under dash evaporator and conventional front mounted condenser.
The compressor is mounted on the right frame rail under the passenger seat. Instead of a compressor clutch, a 400 amp relay contactor connects the 80 amps of 24 volts.
The problem? I ran hard aluminum line for the high pressure and didn't isolate against vibrations. The cab mount rubbed a hole in this line. So it needed a flush, complete lube change and recharge. New receiver-dryer too, naturally. Plus I sealed the condenser-radiator so air flow is much better, reducing head pressure and temperature.
I have a digital ammeter hard wired into the left alternator ground and can attest the alternators drive 100+ amperes when needed and engine over 1500 RPM.
The next add on to the AC is a 200 amp rated pulse width modulated DC motor speed control. This speed control needs an enclosure to protect it from water and dirt..although it would be best to mount it in the cab. Just routing the 4 gauge wires (4 of them) needs another big hole I don't want to drill.
Once installed, instead of a temperature control, it will be a variable speed compressor. So jumping into a hot truck, max speed. Once it gets cool, dial it down. PWM is very efficient means of controlling motor speed and functions like a DC transformer. Motor torque is not impacted, only power which means speed.