New blend motors but............

I've done a search but can't quite get the answer.
Briefly, AC worked fine after I fitted a new condenser and had it re-gassed in the Summer. In September the right hand heat blend motor stuck on cold so not the best idea for the winter and I reluctantly put the car (2000 P38) into local large indepedent for the dreaded dash out trick. New blend motors in, ridiculous bill paid (13 hours) and told I needed a re-gas as they had disconnected the pipes behind the dash for some reason!!! Anyway went and had it re-filled (I watched it being done) and all was fine. Lately I noticed the compressor clutch wasn't kicking in as often as before but did now and again. There is still gas in the system (screwdriver in the valve test) and if I put a live feed direct to the compressor it kicks in. I have checked the supply end of the plug and with the engine running and the AC set to low and there is no voltage.

My question is would the ECU sense a low gas therefore not put power to the switch or could I be looking at something more sinister? All suggestions gratefully received. Would testbook be likely to show anything?

13 hours for dash out and inn to fit new blend motors strange I removed the dash fascia to drill a oring out and put all back in just under 7 hours amd I have never pulled a dash out before one you take the dash fascia out you can see all blend motors if my memory serves me right

As with you question about testbook I would be surprised if it did show anything

I think you may know the answer already? compressor dont you think, seems it could be on its way out, that's what mine started to do, then gave up the ghost

The ac compressor doesn't run continuously and in these cold days the system can maintain a given temp without the ac being on. If when you select the ac off button the light above flashes that means it needs the ac on to maintain temperature.....

If it doesn't flash then it wouldn't need it anyway.

I kind of hope that is it because believe it or not the compressor is covered in my warranty, even though the car is the age it is.

It has been flashing and it didn't kick on. My other cars both have AC and they click on as soon as you press the button. Both have Auto setting too.