2006 Focus ST odd A/C issue

[Tame Technician]

The A/C does blow cold, but the air con compressor seems to be cutting in and out far to much. If I hold a fast idle, say 2000rpm with the A/C on the compressor cuts in, runs for about 30 secs, then starts to cycle in and out (nothing unusual about that you might think) but its cutting in for 10 secs, then out for 10 secs, then in for 10. My other car (jag) with same type magnetic clutch A/C runs almost constantly, maybe cutting out after nearly a minute for a few seconds then back in.

This wouldnt realy be a problem but when driving on very light throttle, say 30 - 50 mph just cruising along, you can feel the engine stumble as the compressor cuts in, feels almost like a misfire, certainly holding back for a split second.

Does anyone have any ideas what this could be.????

The A/C gas was recovered and measured at 380grams, recharge to 600 grams. I've reshimmed the compressor clutch as the gap was to big, is now approx 20thou (0.5mm) but this has made no difference. Cooling fans are running ok, condensor doesnt appear to be blocked and get warm but no too warm.

Help

[Rickyy]

I'm no expert, but don't they have a low pressure switch? Could be that playing up.

[Lumpyuk]

Thought this was the norm for the St with a/c on?

[blueST]

Mine cycles about that often, always has and seems to work fine.