Hello again, so a while back when I finished building my car it had perfect ice cold and mean icy cold air and 1 day just randomly stopped, I finally decided to have a look to see why, I still have full freon after about 2 years, the blower works fine, but I did find the common 10 fuse that goes out for the ac was blown on mine, replaced it and still nothing and it also hasn't blown since, so I checked every fuse and relay in the car and they are all good, check the connection for the ac compressor and it was good so I checked to see if the compressor was getting power with car and ac on and it was getting .025 DC, so I then checked the relay and it's getting about 3.5 - 4 volts. And at this point me and my dad wich has been a mechanic for 30 years are at a dead stop, and nothing comes up when I try to look it up so my last thought was to ask you guys cause sure I'm not the only one to have had this problem, anny help is greatly appreciated. Thank you for your time. Almost forgot to mention is a 2005 jaguar s-type 4.2L v8 sport with auto

 

Bad pressure transducer at the A/C condenser or failed control module in the car. On my S-type it turned out to be both...

 

Can you please elaborate how you know the refrigerant quantity is correct? Not trying to bust your behind, but it's a common misconception that pressure can accurately show refrigerant quantity. Your system could be nearly empty, but if there's still a tiny bit left, static pressure will appear normal. More on that in a minute.

Which fuse? Under the hood, fuses F32 and F38 are both part of the HVAC system. Big difference in troubleshooting, so it's important to know which one had blown.


Yeah, that's basically zero voltage. Your meter is picking up stray voltage from who knows where, which happens with a digital meter. Where did you take this measurement? Was this at the connector to the compressor clutch?

That's an odd reading. Usually it's all or nothing. Could be another anomaly due to the sensitivity of a digital meter. But we can simply say the required voltage was not present. Once again, exactly where did you record this value? There are 5 sockets where the relay is plugged into the panel:

At socket #3, you should have battery voltage available at all times via fuse F32.

At socket #1, you should have battery voltage with the ignition on via fuse F38. Ignition off = no voltage.


More details in the HVAC troubleshooting guide, including details about the lack of correlation between refrigerant pressure and quantity:

https://www.jaguarforums.com/forum/s...ol-how-185002/


In the guide, I tell everybody to test the Dual Climate Control Valve, detailed in post #2. Don't just gloss over that, as it's very important to confirm the DCCV is properly shutting off the flow of hot coolant to the heater core when commanded.

After that, move on to post #5 for details of how to test when no cooling is present. It shows how to test the compressor clutch, etc.

Wiring diagrams can be found here, select the link for your year at the top of the page:

JagRepair.com - Jaguar Repair Information Resource

Figure 03.4 shows the compressor clutch and relay on a non-supercharged V8. Figure 06.1 shows the rest of the HVAC system.

 

Any updates? Seems you were hot on the trail...