Dash display external temp can switch off A/C.

[precopster]

So I just went through the saga of finally fault finding my A/C system in my 2001 T5

Most of the time it would work fine, especially when not stuck in traffic and coasting on highways. On cooler days it was also working OK. This led me to believe that the engine cooling fan operation was suspect. When caught in traffic and in direct sun the A/C would not come on. If I was caught under a bridge in shade back it would come. The cooling fan is commanded on depending on evaporator temperature but only comes on when the compressor is cycling. I was still unsure what the issues were.

I found 2 problems:

1) The external temp sensor in the RHS mirror was often incorrect and read -10C or anything under 0degC at most times. Vida didn't see it as a failure as the temperature was being read and sometimes it was accurate for about 10 minutes after a start then it always plummeted.

2) The small fan at the rear of the temp sensor on the Climate unit had failed. Vida diagnosed this with CCM-0003 low signal cabin fan (not to be confused with the blower fan which is another story)


The diagnostic search function in Vida said that CCM-0003 would prevent A/C operation. Upon looking at the tiny fan at the rear of the CCM sure enough it wasn't turning. I replaced the fan and Vida reported it was turning and drawing current. I drove around for a day and still the A/C was sporadic and intermittent so again back to the drawing board.

I was preparing another CCM (climate module) for Henry to clone for me when I asked him if the A/C is affected by the external temp readings from the RHS mirror. He replied that it would prevent A/C from coming on if readings were below 0 degC.

I had a spare set of power mirrors that I had from a Pick and Pull and replaced the RHS (passenger side for LHD) mirror and voila !! External temp readings were normal and the A/C is now cycling healthily. It wasn't a moment too early as I was already scouring listings for a replacement car for Summer.

Goes to show that even Vida can be wrong and knowledge of the climate system's weaknesses by Henry is what helped me to diagnose. Thanks again Henry!!