Hello. I have acquired a 2008 XJ with approx 19,000 miles on it about two months ago.
Yesterday when I stopped for a light, the A/C began blowing hot. I engaged the A/C again when I was moving & the A/C blew cold air sporadically. Then, I was parked for awhile and the A/C blew hot again; this time I happened to notice the engine thermometer was very high nearly into the red thus I turned off the car. Strange that no sound alarms or error codes ever came up. I decided to drive the XJ home with the A/C off; the engine temperature did not rise so long as the A/C was disengaged. Today, I drove it for 30 minutes with the A/C on and all was fine. Could the internal computer have fixed the issue?
I'm suspecting the Thermostat may be on the way out. But, I thought I would ask whether anyone has had this same issue? If so, what resolved it?

 

If the temp gauge made it to the red then it got REALLY hot, like possible engine damage hot.

Did you hear the cooling fan running when it was hot? Worth checking that it's operational.

There weren't any check engine lights or warnings?

I'd be checking the operation of the fan, check fuses, etc. Would be good to get it to a workshop with a diagnostic system to see if there are any stored codes.

 

Cambo, thank you for the reply. Yes, I did hear the cooling fan running. Yes, strangely enough no warning signals. I am leaning toward the Thermostat mainly because the engine temperature would immediately drop back to normal upon the A/C being turned off. Although, the heat indicator showed it as being high, indications seem to be it was inaccurate since it did immediately drop back to normal. However, I will get it the XJ over to an authorized/approved Jag mechanic to run a diagnostic code prior to having a Thermostat installed. It is my understanding Thermostats are replaced very often on XJ's. Who knows?

 

The fact that the AC blew hot means the radiator cooling fan is not running right and the AC condenser was overheating. Get it checked out. There is a cooling fan module that can be failing as well as other causes. I would replace the thermostat too but it is pretty new, unlikely the problem.

 

Oldmots, Thanks for the info. I will attempt to get the diagnostics read & have a Jag technician fix the problem next week. I will report back with their findings.

 

Took the car yesterday to an authorized Jaguar mechanic. They ran the diagnostic codes & checked everything related to the coolant system; nothing turned up. The XJ still has performed since the day of the few infractions. I did purchase an authentic Thermostat online for $132; I intend to keep it on hand while maintaining an eye on the temperature gauge every time I drive the XJ. Should it run hot again, I will have the Thermostat installed and then report back some time afterward with an update as to whether the issue is resolved; until then, assume it's running fine.