Just purchased 2002 Jaguar S-Type - At times heater or defroster doesn't blow warm or hot air. Buttons fan, temp adjusting controls work, AC works fine gets cold all time just heater not warm or hot.

turn the temperature up to the hot to blend the hotter temperature

the vent adjusting knob/switch has probably lost its connection to the vent adjuster have to strip out the area round heater controls a check the vent operation

Your control panel might be broke..

To troubleshoot this types of problem,click the link below :----http://howtobyme.blogspot.in/2012/02/heater-blows-only-from-defrost.html
--------Go through the procedure to confirm the issue.

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Engine Overheats and heater blowing cold?

http://howtobyme.blogspot.com/2011/11/engine-overheats-and-heater-blowing.html

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Heat blows cold on drivers side and hot on passenger side?

http://schematicsdiagram.blogspot.com/2011/12/heat-blows-cold-on-drivers-side-and-hot.html

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No heat on car? http://technoanswers.blogspot.in/2012/02/no-heat-on-oldsmobile-silhouette.html

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Heater blows intermittently and temp gauge goes erratic? http://technoanswers.blogspot.com/2012/01/heater-blows-intermittently-and-temp.html------------Heater blows cold? http://schematicsdiagram.blogspot.in/2012/02/heater-blows-cold.html
---------Car heater blowing warm, but not hot air? http://schematicsdiagram.blogspot.com/2011/12/car-heater-blowing-warm-but-not-hot-air.html-------- Heater/AC blower motor not working?

http://technoanswers.blogspot.in/2012/02/heaterac-blower-motor-not-working-on.html

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A/C, heater, defroster fan, not working? http://technoanswers.blogspot.in/2012/02/ac-heater-defroster-fan-not-working.html Heater problem? http://technoanswers.blogspot.in/2012/02/heater-problem-on-isuzu-trooper.html---------

This will help.Thanks.

For this types of problem,i suggest you to check this help links:----Car heater blowing warm, but not hot air?http://schematicsdiagram.blogspot.com/2011/12/car-heater-blowing-warm-but-not-hot-air.html
---------A/C, heater, defroster fan, not working?http://technoanswers.blogspot.in/2012/02/ac-heater-defroster-fan-not-working.html
--------Heater problem?http://technoanswers.blogspot.in/2012/02/heater-problem-on-isuzu-trooper.html
---------Engine Overheats and heater blowing cold?http://howtobyme.blogspot.com/2011/11/engine-overheats-and-heater-blowing.html
-----------Heat blows cold on drivers side and hot on passenger side?http://schematicsdiagram.blogspot.com/2011/12/heat-blows-cold-on-drivers-side-and-hot.html----------------This will help.Thanks.

Jaguar S-type 2000 fabrication year is equiped with:
1. Control system = Automatic temperature control
2. System layout = Single evaporator - dual zone
3. Refrigerant circuit type = Expansion valve
General information:
1. System control
1.1. Compressor operation controlled by refrigerant pressure sensor.
1.2. Compressor will not operate if refrigerant level is low!
1.3. System incorporates an A/C evaporator temperature sensor.
1.4. System incorporates an engine coolant heater regulator valve.
1.5. A/C control module incorporates self-diagnosis function.
1.6. The A/C control module fault memory can only be accessed and erased using diagnostic equipment connected to the Data Link Connector (DLC). See picture below:
1.7. Engine Control Module (ECM) incorporates A/C related trouble codes.
1.8. Malfunction Indicator Lamp (MIL) will iluminate if certain ECM faults are recorded.
1.9. The ECM fault memory can only be accessed and erased using diagnostic equipment connected to the Data Link Connector (DLC).
Trouble code Fault location
B1200 A/C control module - internal failure
B1251 In-car temperature sensor - open circuit
B1253 In-car temperature sensor - short to earth
B1255 Outside air temperature sensor - open circuit
B1257 Outside air temperature sensor - short to earth
B1259 A/C sunlight sensor - open circuit
B1261 A/C sunlight sensor - short to earth
B1262 A/C heater defrost flap motor - short circuit, open
circuit, short to earth
B1263 A/C heater fascia flap motor - short circuit, open
circuit, short to earth
B1264 A/C heater footwell flap motor - short circuit, open
circuit, short to earth
B1265 A/C heater air mix flap motor - short circuit, open
circuit, short to earth
B1676 Battery voltage - voltage too low / high
B1946 A/C evaporator temperature sensor - open circuit
B1947 A/C evaporator temperature sensor - short to earth
B1966 Heater output temperature sensor 2 - open circuit
B1967 Heater output temperature sensor 2 - short to earth
B2428 Heater output temperature sensor 1 - open circuit
B2429 Heater output temperature sensor 1 - short to earth
B2477 A/C control module - incorrect programming

Probably the heater control valve, had same issue, started with one side not hot, then erratic, hot then cold while heat is set to hot, now both side are cold to lukewarm. diagnosed as heater control valve, common for jag s-types and x-types. located on the passenger side, down low the side of the radiator, it has several hoses into and out of valve, and a electrical connector.

Heater control valve faulty,
Air lock/blockage to heater matrix,
control unit voltage sender.
Check the above in this order. I assume you are operating heater control functions correctly and the heater display is showing no unusual infor.?
hope this helps. good luck.

common problem, check under dash by the gas pedal if control arms are muving went selecting from ac to heat cuz this it is the control for the vents to go from ac to heat and to defrost.

Replace the temp control on this car, it should be electrical control not cables.