06 jag stype heat all the time ac on left side dash but weak system is charged

Had Similar problem with my 04 Jaguar S Type. There're are many test you can do to see what might be malfunctioning. I new mine need the Heater Control Valve since its was corroded. I replaced the unit which i purchased on Ebay for 89.00. This still didn't fix the problem however i new it was possibly the Climate control unit which will tend to burn out if the HCV is not working for a long time. replaced the unit and working great. If your's just went then it could be just the HCV. This can be a expensive fix by the dealer, so if your handy its not hard to replace the HCV unit. Which is located in front engine under your coolant reserve tank. Check out http://jaguarclimatecontrol.com for possible solutions.