Aircon issues

[faxfan2002]

A few months ago I had the 801225 - "Compressor: shutdown due to negative pressure in the refrigerant circuit".

Took to a garage chain to have it checked out and they said the couldn't find a leak and topped up the refrigerant and all was good.

Fast forward a few months and I'm getting the 801225 again. I'm guessing there is a slow leak, so I purchased -

A/C Pro digital trigger and A/C pro A/C recharge (that seals small leaks).

However when I connect the A/C Pro digital trigger it reads 0 PSI, I assume it's one of three things -

1. Looking at the connectors I suspect it may not be fully connecting - assuming the pin needs to be depressed in the car fill port?
2. Showing 0 PSI because the compressor is shutdown?
3. It is actually 0 PSI?

I connected up the refrigerant can to the trigger, connected it and as soon as I pressed the trigger it came up with 60 PSI, I disconnected it and the trigger still showed 60 PSI, pressing the trigger (when disconnected from the car) it hissed and went to 0 PSI.

Any advice / guidance would be gratefully received

[faxfan2002]

I'm using the "yellow" port not the "blue" port. It's a 2014 650i.

[Qsilver7]

From what/how you wrote what you did…were you following the instructions that came with your kit? Or are you just screwing the connector on and pressing the trigger on the can (that’s what you wrote). Aren’t there other things you’re supposed to do? If yes, then what where they and did you do them?

The engine & compressor needs to be running and the AC turned to the highest fan setting and coldest temp setting…you never mention if you did any of that.

[faxfan2002]

Yes, I followed all the instructions very carefully - aircon on max a/c, blow for several minutes etc. before doing anything.

But the compressor is shutdown as per the error message from the car, wonder if that could be the issue...

[arucano]

If the system pressure is too low, the compressor will not engage. It could also be a faulty pressure sensor. If the gas pressure is high enough for the compressor to kick in. Test the compressor clutch resistance for continuity. If that is OK, the problem is in the control system for the clutch (I think there is a relay in the circuit).
If someone on the forum has a diagram, it would be handy if it could be posted so the diagnostic steps can be worked out.