Technical Aircon not working

[JohnBessacarr]

Hi All,

Need some advice please. I recently purchased a 2014 Bessacarr motorhome, on a Ducato x250 chassis. The standard aircon is not working. The compressor doesn't want to engage. I've run my diag tool, but no issues reported. Checked the obvious areas, like the fuses, relays, belt on the compressor, etc... but no issues found. The strange thing is, when I turn ON the external lights, via the stalk, the aircon light in the switch also turns ON. So, it seems there is an electrical issue. The passenger side, side light is not working. Could it be linked? Any thoughts, suggestions would be appreciated, thanks.

 

[lycopersicum]

Besides a possible electrical issue, it seems that the compressor will not engage if the refrigerant leaked away.

There is a Fiat service news about possible breaking/chafing of the refrigerant pipes near the radiator when they are incorrectly routed under/over each other, on the 2006-2014 models.

 

[JohnBessacarr]

Ok, thank you. I will check those pipes. I did have a mobile aircon guy come and re-gas my aircon recently. He said the gas was already quite full, and confirmed no leaks.

 

[lycopersicum]

It's probably not that then, but here's the relevant info for reference:

 

[JohnBessacarr]

It's probably not that then, but here's the relevant info for reference:

View attachment 472522

Ok, thank you for sharing this information.

 

[AsdaPricey]

Hello @JohnBessacarr

I feel your pain - the Ducato ac system is fragile.

I’ve left mine as not working, a job for another day.

This thread may help you - if you find the relays as depicted in the diagram in that thread and send power to the compressor you can at least see if the compressor works

 

[JohnBessacarr]

Thank you for this advice. I have located the relay, and will try pushing 12v to the compressor.

 

[JohnBessacarr]

Hi @AsdaPricey

Located the compressor relay in the engine fusebox, and connected the 12v to the compressor terminal, and it engaged and the aircon started working So, as a work around, I've fitted a toggle switch to manually turn the compressor ON and OFF using the relay location, and put it inside the cabin. Thanks again for your advice, from one very happy guy!

 

[AsdaPricey]

A semi win there then. A few questions that spring to mind;

Did you test the relays in case that’s all that was at fault?

Did you test the continuity of the wiring - switch to ecu to relay ?

How is your jury rig toggle switch wired ? Is the relay still handling the current consumption?

 

[lycopersicum]

I've attached the description of the compressor wiring and function from elearn.

There's two fuses and two relays involved, T09 controlled by the ECU activates another relay T05 that activates the compressor solenoid.

It sounds like you got it working after bypassing T09 with a switch, which would indicate that the problem was somewhere on the ECU/sensor side (maybe F18 or T09 itself), or with the dashboard controls.

You will lose a few safety features controlled by the ECU:
- not engaging the compressor without sufficient gas pressure to prevent damage
- ditto if engine coolant is too hot

The ECU also disables AC under high acceleration, not sure if to protect it or to make all power available to the wheels.

 

[lycopersicum]

And here's the more general description of the electrical controls for the AC.

It says: "the climate control system control unit H080 is backlit, via pin 5, when the side lights come on."

Is that what you're observing or did you mean that the AC on light comes on, not just the backlight?

It's possible you do have a common problem to the AC and the side lights, maybe a bad earth, or some common wiring damaged.

 

[jackwhoo]

If you have no working outside temp display on dash .... that will stop ac working. The reason ac ecu needs outside temp signal is to stop ac being switched on at very low temperatures.

It is very common for the door mirror containing the outside temp sensor to get smashed, then replaced with a cheaper mirror without the temp sensor = no ac

 

[SteveiC]

If they are over pressure the a/c will not work.......is it possible that someone with a DIY kit put too much pressure in the system?

has it ever worked? what was last done to the system before it stopped working?