My 2002 XK8 (44000 mi) works fine for first 20 minutes or so after startup then blows cool (not hot or cold) air. I id have the system charged. Checked fault codes and got the following

14 Water temperature input malfunction Instrument cluster output Refer to PDU

23 Refrigerant pressure switch malfunction Harness / connector fault Switch open / short circuit Refer to PDU23 Refrigerant pressure low refrigerant charge *Leak from damaged pipe or joint Rectify as required and recharge system

44 Defrost vent motor fault Harness / connector fault Servo motor seized or sticking Flap seized or sticking Refer to PDU

45 Centre vent motor fault Harness / connector fault Servo motor seized or sticking Flap seized or sticking Refer to PDU

46 Foot vent motor fault Harness / connector fault Servo motor seized or sticking Flap seized or sticking Refer to PDU

 

Have you checked your fuses ?

 

As you have had the system recharged and there are presumably no leaks, fault 23 should no longer apply.

The AC (heater) Unit has two Servo Motors on the LH side (items 2 and 3):


(click on the image to enlarge it)

These motors move the flaps to redirect the airflow. Two faults are known:

1. sticking
2. seals breaking up preventing proper closure

This covers faults 44, 45 and 46. The flap positions only affect airflow - they do not affect temperature. A regular for causing cabin temperature issues is a blocked In Car Aspirator. This is behind the small grille in the dash panel:





It collects dust and sends false signals to the AC Module.

Instead of leaving the AC permanently on the preferred settings, a good preventative maintenance routine is to cycle the system through MAX hot to MAX cold and airflow from screen to footwell on a monthly basis. This helps prevent any of the control valves and flaps sticking.

Graham

 

Is there some way to clean aspirator without taking dash board apart? Perhaps vacuuming.

 

I exercised my AC for several days as suggested and it now seems to work. Went out yesterday to "leaf peep" and it blew cold all day.