02 Astra club estate My workshop manual states "don't use the air con if the refrigerant level is known to be low, otherwise damage to the compressor will result" How do I know? - there seems to be no way of checking as far as I can see. And moreover the pump is a belt-driven mechanical thing (I think) So how do I not use it if the level is too low, without stopping the car and calling-out the breakdown wagon?