A/C Compressor

[woodways3]

Hi my A/C Compressor is not working .The pulley spins freely,i know about the gap .My question is the power supply to the compressor has a type of bullet connector just in front of the unit .i pulled this apart and connected a meter between the two ends turned on the ingnition and A/C switch .Should there be 12v showing?? If so im confused because as far as i can see the fuse in the engine bay alongside its relay seem ok .I swopped the relay for a similar in the fuse box.I must say im rubbish at car electrics.Ive already packed the pully out a bit but no joy yet. The car is a 2002 V 70.

[cheshired5]

With cabin temp selectors at minimum, you should get voltage at the compressor plug with the engine running.
It's not going to power up with just the ignition on.

[woodways3]

Originally Posted by cheshired5

With cabin temp selectors at minimum, you should get voltage at the compressor plug with the engine running.
It's not going to power up with just the ignition on.

Hi back to my question.With the engine on and of course the A/C switched on should the voltage at the compressor connection be 12v or is it less? If it should be 12 im lost as as far as i can see in the fuse box in the engine bay the fuse and relay seem ok.Being an estate there are more fuses in the back but no idea what for.

[cheshired5]

What voltage are you getting?

[XC70Bob]

If you A/C system has lost all or part of its charge then you wont get any voltage on the connector in question to prevent the compressor from damage.

[woodways3]

Originally Posted by cheshired5

What voltage are you getting?

I was struggling holding the meter points in the connections whilst the engine was running ,i think it was 2.6 v

[woodways3]

Originally Posted by cheshired5

What voltage are you getting?

I was struggling to hold the meter points whilst the engine was running ,i think it was 2.6v

[stuart bowes]

in situations like that I generally wedge a pin or nail into the connector and use crocodile clip connectors

just for fear of putting my hand anywhere near the belts

interesting to know about the low on gas / ac not working thing, would the light still light up on the button, would there be a DIM message or anything. just curious

[XC70Bob]

Originally Posted by stuart bowes

in situations like that I generally wedge a pin or nail into the connector and use crocodile clip connectors

just for fear of putting my hand anywhere near the belts

interesting to know about the low on gas / ac not working thing, would the light still light up on the button, would there be a DIM message or anything. just curious

There are normally 2 switches in any A/C system one for high pressure and one for low pressure,

I doubt they would stop the button light from being on as the system could actually run and just trip one of these switches under certain conditions , for example if your radiator fan were to fail you would likely trip the high pressure switch in traffic, but it would reset once you got to open road and had good air flow over the rads.

A low quantity of gas that's not low enough to actually stop the system altogether often cases the compressor to short cycle , because the low pressure switch trips stopping the compressor until sufficient gas has passed round the system for the switch to see sufficient pressure and allow the compressor to run again.

I doubt there would be any error message display either ( did not get one on my 2005 XC70 ) but you should be able to read the switch state and system pressures via vida.

[volvo again]

If you're trying to measure voltage at the plug you need to connect the meter between plug and earth, not inline

As stated, if there's no gas or a fault elsewhere you won't get anything at the compressor, various sensors/pressure switches won't allow the compressor to run.