I have the same problem. Change your heater hoses, top and bottom !
You don't change it. Ask your driver to get the car at a specialised service :)
You need to replace the heater coil !
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Check the following items............... 1. A/C heater controller. 2. A/C heater controller doors.
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look under the car from the front its just above the main cross member a little bit to the driver side the wirers are on the passanger side you will need a 15 mm socket to remove it
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