Technical Air con pressure sensor

[BlueDan]

Does anyone know where it is, on a 100HP in particular, so I can try to test it?

Fuse 19 and relay 05 are OK and it was only recharged around this time last year. Hopefully it's this sensor at fault fooling it in to not starting (no click or change in engine idle noise) and there isn't that bad a leak somewhere instead. :/

I've followed the pipes out of the bulkhead, one through the compressor, then both under the header tank, behind the headlight and down to the condenser and I can't see it.

 

[Most Easterly Pandas]

IIRC drivers side (RHD) just where it enters the condensor (lower pipe). Near the oil filter / water pump

 

[BlueDan]

Ahh yes, there it is (thanks!) - simply (by small FIAT standards) remove the front fog light to view it. Access to the rear to probe at it with a multimeter, without removing it and letting any pressure (which may or may not be there) out of the system will require the use of the pit in my cousin's garage.

 

[PuntoHowTo]

Unplug it and short the connector, if the system springs into life either sensor is dead or no pressure in the system, although the chances are you have a leak somewhere

 

[BlueDan]

Yeah, I was considering doing that instead as a brief test - easier than trying to probe at it, given where it is. I'm not sure what value resistor I'd need though, if any ("signal needs to be between 1v- 4.5v before it will say OK and allow compressor to start")? - I've got some 330 ohm already here.

 

[jrkitching]

although the chances are you have a leak somewhere

:yeahthat:

I'd say the odds favour losing the refrigerant over a failed pressure sensor.

 

[BlueDan]

Yep, tried bridging with a 330ohm resistor and a piece of wire (one then the other), no difference after running for ~10 minutes... arse!

I'll find a specialist that'll do a dye test plus required repairs once work allows.