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Blog Title:
Autologic - Friday Fault 2 Fix: Heater only blowing hot
Posted By:
Admin Admin
Blog Description:


Brands: Jaguar

Models: S Type 2002.5 to 2008

Symptom: Heaters only blowing hot




Cause: various faults on the heater


  1. Remove passenger side dash end panel and locate connector FC4 (14-way green connector.)
  2. Disconnect the connector and on the male side, measure the resistance between pin 9 Brown/Green and Pin 10 Brown/White (On a good Circuit you should have 30 ohms)
  3. If you do not have 30 Ohms, go to the heater valve and measure the resistance across pin 3 Brown/White and Pin 1 Brown/Green of the heater valve – this should be 30 Ohms – if open circuit replace valve and recheck operation.
  4. If you have 30 Ohms across pin 1 and 3 of the heater valve check wiring integrity from connector FC4 Pin 9 (Brown/Green) to Pin 1 of heater valve and FC4 Pin 10 (Brown/White) to heater valve pin 2 If open or short circuit repair as necessary.
  5. Reconnect connector FC4 (14-way Green) and measure the voltage on pin 9 and 10, when the climate control is set to hot you should have battery voltage on both pins and when set to cold you should have ground on both pins.
  6. If you do not have battery voltage check pin 2 Yellow of heater valve – this should be permanent battery voltage, this is fed from fuse 32 (10a) in the engine bay fuse box
  7. If pin 9 and 10 do not switch to ground, suspect an internal control module fault. NOTE: Do not fit another control module until the heater valve has been replaced, as sticking heater valves are the main cause of module failure.


Component Locations:


Heater Valve

  • Petrol Models – On right hand side of radiator under expansion tank
  • Diesel Models – In right hand front wheel arch liner in bumper corner

Climate Control Module

  • Navigation Models – Remote climate control module located above glove box secured to dashboard, glove box requires removal for access.
  • Non Navigation models – Module is the Control panel located above the radio in the centre console.


Courtesy of Autologic: www.autologic.com