Aircon (again!)

[steve329]

Right so the air con seems to be working well at the moment (still doesn't come on all the time but it mostly plays ball) apart from Iv noticed that sometimes you can hear a couple of quiet clicks from behind the dash (sound like relays) and you get a slight judder from the engine as though load has been applied or removed, this happens once every minute or so (not times it) but pretty regular, only happens when air con is on? What could this be?

[Mirez]

That'll be the compressor clutch relay turning on/off - perfectly normal.

You can't run the compressor non-stop as it would ice up the lines but since the compressor is driven directly from the aux belt of the engine it would be if there wasn't some intervention. An electromagnetic clutch is used to engage the compressor, which is electrically driven via a relay, as the relay energises a click is heard and the clutch engages thus putting a hefty load onto the engine (which is the jolt you feel).

[steve329]

Ahhh cool (no pun intended) I thought it may just be normal but wanted to check, as sometimes the air con doesn't come on, although it is deffo getting better, I wonder if the last owner rarely used it and it's taking some loosing up :-/ I do find if I'm stationary and turn the air con on a blip of the throttle helps