So my air con clutch is not engaging.

I'm seeing 8.65V at the compressor (whether air con should be on or not) with what looks like an occasional higher spike (but my digital multimeter can't really keep up).

I'm pretty sure the climatronic unit is working OK as the engine fans spin up when it thinks the air con should be on and the internal blowers fire up correctly etc.

Any ideas where I should start looking?

There's a 4-pin connector that slots in a bracket above the starter motor. Two of the wires go to the a/c clutch (the other two go to the alternator). It's not uncommon for bad connections to affect the operation.

There's a 4-pin connector that slots in a bracket above the starter motor. Two of the wires go to the a/c clutch (the other two go to the alternator). It's not uncommon for bad connections to affect the operation.

Thanks, I'll check it out.

Life's been a bit manic so apologies for being slow to report back.

I wiggled the wires as suggested above and I can now feel a change in engine revs when the aircon engages (by turning on/off the econ button). However Kwikfit have just done a regas and its still not running cold.

What do I try next?

Take a look inside the a/c pulley. Does the nut in the centre rotate?