With the AC button selected, and the car running the AC compressor constantly clicks on and off every few seconds.
Its not mechanical as the compressor, gas level and high pressure switch have all been checked. The PDM is turning the compressor output on and off continually which can be monitored, but if I manually test the output it will run continually without an issue.
I'm trying to understand why the PDM logic has been set up the way it was and why it constantly turns on and off.
The setup is probably not optimum, but this is the way it currently is:
The physical wiring is simple. There is no temperature control circuit, just on or off. When AC is switched at the CAN keypad power goes from the PDM output to the compressor, through a high pressure switch to the single wire point on the compressor clutch, and a signal wire from the same point at the compressor end goes back to a PDM input to tell it the compressor is running. The PDM uses the compressor running signal to tell the dash (Plex) via CAN and the dash tells the ECU (Syvecs) via CAN that the AC is running. It was done that way because they ran out of inputs on the ECU to wire the AC directly.
So the ECU isn't wired to and doesn't control the AC. Only the PDM controls the AC.
The settings in the PDM are as follows:
One of the keypad buttons is designated as the AC.Button channel.
A function AC.Sw is setup based on the AC Button condition:
The 5A compressor output AC Compressor turns on conditional on the AC.Sw value
An input pin designated ACRunning receives the looped back signal wire from the compressor and a CAN output sends that info out to the ECU via the dash.
Is this how it should be setup and are these settings causing the compressor to continually turn on and off?
I don't understand why the output condition was setup using a 'flash' parameter, but if I just change it to AC.Sw true the AC doesn't come on at all.
