Hi everyone,

I'm troubleshooting the AC system on my 2014 MINI Countryman and I'm trying to figure out whether I'm dealing with a failed compressor/compressor control valve or a control/electrical issue.

Symptoms:

- AC does not turn on
- Compressor never engages
- No cold air

Tests already performed:

- Checked the passenger-side AC fuse
- Replaced the AC pressure sensor/switch
- Tested AC relay separately by applying 5V, and the relay clicks
- Bridged/jumpered the AC pressure sensor connector as a test

When I bridge the pressure sensor connector, the engine RPM changes slightly, almost like the DME is recognizing an AC load request. However, the compressor still never engages.

I also vacuumed the AC system and attempted to recharge it, but it only accepts about 100-150 grams of refrigerant before it basically stops taking more. My understanding is that once enough refrigerant pressure is present, the compressor should engage and begin pulling more refrigerant into the system, but that never happens.

One thing I'm also confused about: why would the AC system only accept a small amount of refrigerant, around 100-150g, instead of taking the full specified charge?

Is that simply because the compressor never engages and therefore does not pull refrigerant through the low side, or could it indicate another issue such as a blockage, expansion valve problem, incorrect charging method, or pressure/temperature condition preventing more refrigerant from entering?

I checked voltage at the compressor connector and measured 0V, although I'm not sure whether this compressor receives constant voltage, PWM control, or is controlled another way.

At this point, I'm trying to determine whether this points more toward:

- failed compressor
- failed compressor control valve
- wiring issue
- relay/control issue
- DME/IHKA not commanding compressor engagement
- another sensor or control module preventing activation

The RPM fluctuation makes me think the car recognizes the AC request, but something is preventing the compressor from actually being powered or commanded on.

What would be the next logical test? Should I be checking for DME command, PWM signal, compressor control valve resistance, relay output, wiring continuity, or something else?

Any advice would be appreciated.

Thanks!