My Focus saloon 2003 , has just started running the air con all the time even though it's turned off at the switch. Any ideas please . Peter 

1 hour ago, Welder said:

Focus saloon 2003 , has just started running the air con all the time

Hi,

I am assuming it is manual a/c, not climate control.

Also I am guessing you have checked that the airflow switch is not in the screen defrost position, as this triggers the a/c to come on.

On the Mk2 Focus, and on US Mk1 Focus, there is a GEM test. The GEM handles the a/c button & light.

"Press and hold in the rear demister button while starting the car and you will get a tone.

Once activated the test mode will sound a tone when any switch or lever is triggered.

Open each door in turn, bonnet, boot, wiper, indicators etc and a tone will sound/hazard lights will flash which will make it easier to pin down any faults."

This should check that the a/c switch is working. Also check if the indicator light is going on & off.

Usually, the pcm (aka ECU) controls the a/c. It operates a relay (R11?), which then powers the electro-magnetic clutch on the compressor. Try removing the a/c relay, or the a/c fuse (F15?), to check if the relay is jammed on. 

If the compressor runs without electrical power, then perhaps its clutch is jammed by dirt or corrosion.

If removing the fuse stops the compressor, then check the relay and whether it is being turned on. There also seem to be a couple of Diodes in the FJB, check that these are not short circuit, as one may be on the a/c circuit.

 

Thank you for your reply will check when off work next . Peter