Cheers All,

Can anyone tell me, if the AC system has no refrigerant in it, will that prevent the climate control panel from receiving voltage? My Climate system does nothing when I turn the fan switch. No mode selection, nothing. Any help as always deeply appreciated. Troubleshooting tips to determine if my AC control head is functioning properly. Helpful links.

Thanks
Mike

 

Hello,

A low/no refrigerant situation would not prevent power from reaching the Climate Control Panel. The pressure switch in the refrigerant system is an input to the Climate Control computer, which then prevents the A/C Compressor Clutch relay from being energized.

Have you checked the small things first, like fuses, and connectors? Do you get any backlight illumination of the panel when the exterior lamps are switched on?

I seem to remember there being a small micro switch for the Fan Speed Knob, which, IIRC, will prevent the system from functioning when it fails.

EDIT: Check out this link. It is for a 1994 but much of it applies to your 1991. There is a great How-to by Zenidyle within.

Nick

 

Hi Mike,

The refrigerant level has nothing to do with power to the climate control panel. The panel is inextricably linked to the Climate Control Microprocessor (CCM) and the Central Microprocessor (CPU), so off the top of my head I can't recall where the power comes from. You should be able to trace it in the schematics in the 1991 XJ Electrical Guide, which you can download at the link below courtesy of our member Gus and his website, jagrepair.com:

http://www.jagrepair.com/images/Elec...Electrical.pdf

Cheers,

Don

 

This has been a problem for 25 years!!!!!!!!
Please read the TSBs I uploaded to the large file area and GUS should have this on his site also.

bob

 

Thank so much for all of your replies. I really appreciate it. This points me in the right directions. I love this forums!!!!!!!

 

Hello Mike
Just in case, read https://www.jaguarforums.com/forum/x...onsole-170129/
This where I explained that having no voltage at the panel comes from a mis-connection of 2 of the 3 connectors (under the right underpanel, close to the central console)
Cheers