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Few days ago I noticed that the aircon in my shed4 is not working, it’s not blowing cold air at all. I had it serviced last year as a preventative thing as I had no information when it has been done previously.
When I turn the AC on, the light on the dash stays on as if it was working, same with the MAX button. Unfortunately the compressor does not kick in, checked visually that the middle part of the pulley is not spinning when AC is engaged.

What I have checked until now:
- No error codes
- Transport mode is not on
- I have checked in INPA that the radiator fan is working in all of the speeds
- I have engaged the AC clutch in INPA, does not engage.
- There is pressure in the system (~6 bar in INPA)

What should I check next? I have yet to check the fuses/clutch relay. Of I understood correctly, the’re located behind the glovebox?

I went through many of the topics with a similar issue but could not find a solution to my problem in them.

There is a thin trigger wire to the air-conditioning compressor. This is known to break on other BMWs/MINIs. I doubt the Z4 is immune.

I'd be testing that first - probably by feeding 12v directly into the relevant pin on the relay socket, or directly to the plug on the compressor - if accessible - and seeing if the clutch engages. If not, probably the wire (or the clutch).

Like this: https://www.zpost.com/forums/showthread.php?t=850538

(Unfortunately, not all models have this as a separate part of the compressor - looking at you, R53!, so hopefully it is separate as in that link - although I don't know what engine/chassis that is for)

May or may not be a thing…. But had a similar issue with my wife’s car, the system had completely run out at one point as she always drove with it off ‘to save fuel’.

The HP side had run out as had the LP side, so even after taking to garages to get gassed (LP side), the pump wouldn’t engage as the HP side was still sensing as low so protects the pump.

Ended up jumping the relay terminals to engage the pump, whilst gassing at the same time to force it to charge. All seemed worked fine after that!

Is your temperature reading ok on the dash? External temp sensor is part of the decision circuit

And if that’s ok I’d be looking at the green wire next

Does the engine cooling fan spin up when AC is switched on?

TriggerFish, checked the cable visually and it seems to be in good shape. I know what you mean with the R53, replaced few coils on those things…

m_lehcim, cheers mte, thats somwthing to keep in minf when I go and see the regassing chaps probably sooner than later

bigwinn, temp on the dash is fine; fan does not start when the AC is on; took the cover off to have a look at the green cable and visually looks fine but apprently it can be rotten on the inside. Any easy way to check it?

And something else I have noticed is that the fan aux belt has a very tiny chirping noise that was not there. Belt is a Contitech with ~2000 miles and I replaced the tensioner couple weeks ago. What did look a bit strange is that it seemed as the ac compressor was not turning at all, could that be the source of the noise? Belt just rubbing on the pulley without it spinning?

I might be just imagining things, would not be the first time. I think I have to take the belt off and try to spin the compressor just to be sure.

It’s a fairly easy job to splice in a wire to bypass the connector

I found another topic where someone had issues with the fan and the problem was the green cable. But he was unable to activate the fan with INPA and got some error codes. https://z4-forum.com/forum/viewtopic.php?t=105320#top

My fan works when activated in INPA on all the speeds, thats why I’m confused.

m_lehcim wrote: Mon Jun 02, 2025 6:34 pm The HP side had run out as had the LP side, so even after taking to garages to get gassed (LP side), the pump wouldn’t engage as the HP side was still sensing as low so protects the pump.

Sorry but that is utter nonsense. Your garage obviously knows absolutely nothing about an A/C system (which is worrying and dangerous TBH).
A/C are NEVER (or shouldn't be) recharged from the low side these days. The refrigerant should be 'weighed' in, as a liquid, from the high side.

The refrigerant system (gas) is a single circuit, it doesn't 'run out' on one side. It can't. At rest, both 'sides' will be the same as they equalise out when not running. The HP (high pressure) switch is there to protect the system from, basically, bursting. The LP (low pressure) switch is there to protect the system from running with too little refrigerant (or basically empty) and seizing the compressor.

The OP says his scan tool is showing pressure, at rest, at 6 bar (89 psig) which is more than enough to satisfy all safety switches, so the clutch should engage. It is either an electrical problem, or the scanner/ sensor is lying. A quick press on the low side A/C line schrader valve will tell if there is definitely pressure. DO NOT try this on the high side schrader, or you will get liquid and it will burn you!

Geting back to this as it got very warm on the track yesterday. Fuses checked and they’re both fine. Tried to find where the relay for the aircon is to check if there is continuity on the magnetic clutch. I know there are some behind/below the fusebox under the glovebox but none of them is for the AC

Check the wires on the pressure sensor which sits near the rear of the engine bay. I had one where the wire was broken but looked secure until I wiggled it.
Have you checked the pressure sensor itself is ok?
If that doesn't detect any pressure then the compressor won't kick in.

Wires/connector seem to be ok. Fired up INPA once more just to check, I thin everything is in order.

Is the aircon relay by any chance located in the small box under the bonnet?