Car air conditioning not kicking in.

[dobbslc]

The garage can't look at it for two weeks so we had a prod last night and found that the compressor clutch works when given a 12v feed, the relay functions when removed and tested and the cable between the relay and clutch is good.
The relay isn't getting a signal from the car so it's probably low gas or faulty pressure switch.
What I did find was a resistance of 2 ohms between the battery terminal and the car body on a piece of cable only 12" long!
I disconnected it all and cleand everything up but its made very little difference.
I even re crimped the lugs.
I need to look at this again as I think 2 ohms is to high for a short bit of 25mm cable.
I've got the pressure gauge now so will try it tonight.

 

[keithski122]

Its a mazda so there’s probably nothing wrong apart from being low on gas.There again there will be a reason why its low on gas.
With diagnostics always start with the basics.

 

[Ubique]

Was the 2 Ohms with the battery disconnected? if not, then the reading will be incorrect. It's more accurate to measure volt drop if checking a 'working system'.