My 2003 started blowing hot air out of passenger side and rear seat vents unless I kept the temperature setting on both sides all the way down to 61 degrees. At the advice of people on the forum I replaced the heater control valve. Same problem remained. Took it to a dealer and had the climate control module replaced under an extended warranty. The same problem still remains. When you first start it up after it has been sitting in the sun it comes on and cools the car down and the fan speed decreases, then all of a suden I get this strange heater like smell and hear comes the hot air. I do not know what it will do in cool weather since it has been unseasnoally warm in St Louis until just recently. Any ideas? Could it be the after market heater control valve is at fault? Although it is doing the exact same thing as it did befor I replaced the valve. It may be my imagination but it seems hard braking or turning sharp corners may cause it. Don R

 

I'm thinking one or both internal temperature sensors. I have the opposite problem -- after a year with no heat, I replaced the DCCV while the engine was apart for other reasons. Now I get heat, but only if I dial in 73 degrees or more. I plan to look into the temp. sensors next...

 

I went to jaguarclimate control.com and solved the problem. Turned out it was the internal temperature/moister sensor was dirty and covered with lent. I cleaned it and everything works as intended. this site is great. Read the diagnose it yourself section very carefuly and you can identify your problem Don R