having problem with my 2007 Jaguar Xk convertible. Runs cool without ac on, once you turn on ac the temperature goes way up. Fans are working and there is no leakage, thermostat has been replaced and has plenty of fluids.
Any ideas on what could be the problem?

 

Is the coolant mostly water? I bought a Thunderbird waaay back when for super-cheap because the seller said he could never keep it cool. I had to pull over half-way home because of it, but when I checked it (after it cooled all the way) he had put 100% straight antifreeze into it. I drained half the cooling system and filled it with water and viola! It never had a problem after that.
I'm just looking at the cheapest, easiest fixes first for ya.

 

Just because the thermostat has been replaced doesn't necessarily mean it's functioning properly or is not put in backwards. This is typically a thermostat problem. Also, how do you know the temperature is going way up since there are no gauges, do you have a Torque App set up to read temps?