Daf xf 105 a/c

[airconmanbuddy]

Hi all :off topic:, hopefully i'll get some decent input here,

I'm currently working on a Daf truck XF105 is the model, The problem is the a/c wont engage, We have tested all the points and switches for voltage, The system is all set to go there is even voltage down to the compressor but it does not engage? The compressor is brand new so there is no fault there.

Would there be a sensing voltage there at the compressor? I'm thinking it maybe the compressor relay in the fuse board.

All help welcomed :)

[monkey spanners]

Have you got continuity through the coil? Is there 24V (or 12V if its a 12V system) at the coil, Both positive and negative?

With the engine off but the air con set to run with power to the coil, push the clutch plate in with a handle on a hammer or similar, if it then pulls in the air gap is too big due to wear or wrong clearances set.

Is it a 24V coil but a 12V system?

[charlie patt]

you may have voltage but you may find when you connect comp you lose voltage if this is the case check the loom where the cab lifts up this is where you will find a break when you put the loom under load it may have a break in a wire and stops passing current when running use a voltmeter and sea where you lose the voltage

[airconmanbuddy]

Yeah had it running and the voltage is always there? I've not checked for continuity actually I will try that, and the coil is 24v.

I had this once on a Mercedes truck and it had voltage at the clutch but when the ignition was turned on it dropped the voltage completely. We found it was a little circuit board which controlled the fans and direction of the air which was causing the fault but this system doesn't have this setup.

[airconmanbuddy]

And i will try that with the hammer handle on monday,

Thanks for the input guys much appreciated

[charlie patt]

also check the pressure switch by the condensor on the front step the wires get poor there and when under load you get a bad resistance enough to read on a meter but not enough to pass current the plug arangement is poor on these and the man units

[airconmanbuddy]

also check the pressure switch by the condensor on the front step the wires get poor there and when under load you get a bad resistance enough to read on a meter but not enough to pass current the plug arangement is poor on these and the man units

There seems to be current going through it i've had it apart all seems good there i think but will double check monday thanks :)

[airconmanbuddy]

Sorted, thanks or the input. It was a bad earth, i've taken the earth straight to chassis now.