This involves a 1998 XJ-8. Upon startup, the A/C cools the cabin down, but after the cabin reaches the desired temperature the A/C starts blowing hot air. Even changing the temperature setting to Low at this point does not make a difference. The refrigerant level is OK. The ambient temperature sensor appear to be working properly as the system does display the correct outside temperature. Is there an in car temperature sensor that could be faulty, and where is it located?
Thanks.

 

On my XJR I believe it's located right next to the trunk release behind the grill. See Image... Somebody please correct me if I'm wrong.

 

With thanks to Gary Breyer, I don't know where he stole it from but this prevents me from having to type it out myself:

1. With ignition off, hold down AUTO and RECIRC buttons and then
switch on the ignition

2. Press AUTO button and, if ZERO shows, there's no stored error
codes

3. Press FACE button repeatedly to scroll through stored fault codes

4. Press FACE and HEATED REAR WINDOW buttons together to clear a
fault code.

5. Repeat no 4 if there's more than one code showing

6. Press FAN button to exit

 

Thanks for the information on retrieving the fault codes. Much appreciated.