Hi all, brand new member here, just bought an ‘06 4.2 S Type. Essentially it is a great motor but has a few little things that need sorting out. 
I thought it was worth the gamble! 
The seller plugged in a code reader and we got code P0646. I know this could be several things in the AC system, what should I check first? Is there a fuse or relay that controls this and are they located in the trunk fuse box or under the hood? 
TIA for your help 

Mike. 

• Faulty Air Conditioning Clutch Relay
• Air Conditioning Clutch Relay harness is open or shorted
• Air Conditioning Clutch Relay circuit poor electrical connection

Worth checking the above first.

Figure 06.1 of this electrical manual may help. http://www.jagrepair.com/images/AutoRepairPhotos/CarPDFFiles/SType/S-Type-Electrical-2006on.pdf

Hi

code p0646 relates to the air con compressor clutch, open or shorted, odds are the wiring has broken, bad connector or clutch winding burnt out, should be easy test with a multimeter

most common problem with s-type is either the DCCV, dual coolant control valve, sit just behind radiator and or Climate control module, sit above glove box, usually dccv fails and either sticks open or shut, giving either permanent hot or cold heater, sometime they take out the climate module, these can be usually fixed, when you pull the apart you can see blown tracks that just need repairing

cheers

Joe

https://jaguarclimatecontrol.com/diagnose/

Can someone please help me out, I cant find anything in the owners handbook showing the location of the relay that controls the ACC.

I have googled it but can only find the 1999-2001 diagram.

Apart from checking fuses and relays, what is the best way to diagnose what the problem is?

I'm crap at the diagnosing of things, but when I'm pointed in the right direction i can usually get it done.

hi

if its blowing hot, means dccv is passing hot water into the heater matrix, no amount of ac will cool it

has to be a faulty dccv heater water valve or climate module

all the info you need is here http://www.jagrepair.com/

its R8 and Fuse 32 in engine bay fusebox

cheers

Joe

 

UPDATE:

I have changed the DCCV but still no cold air. So I suppose the next step would be the module? Any other suggestions please TIA 

Hi all, We changed the DCCV and still had no cold air. I called our local dealership and they told me that almost always when the DCCV goes it blows the module.

I got the module out and found a burnt line on the board, after a quick youtube search I learned how to repair it and still no joy.

Is there anything else that i can check to get this problem solved?  I have enlisted the help of a local mechanic,he has checked the compressor and the electric clutch and says they are both good. Is there anything else that i am missing?

Many thanks

I have no knowledge of the Climate Control Module but, having worked in electronics (Radar) for many years, in my experience if the track has burnt out there is a good chance the fault has caused (or been caused by) component failure somewhere else.

Rob

 

hi

if dccv did not work its usual the climate module above the glove box

climate module usually blows a track on the board which can be easily repaired by linking out blown tracks, I would link out with 5 amp fuse wire which will offer future protection

as said above, tracks fail for a reason and on the S-type its usually a faulty dccv, since that has now been replaced you should be ok, once the climate module has been repaired or replaced

cheers

Joe

We tried repairing the track on module with no luck, so in the end we are replacing everything, we have replaced the DCCV and the module, still no change. So we have a new compressor and condenser and dryer on order. It was a decent price for the whole kit so decided to go with it. 
of that doesn’t work I’m giving up! Lol