A/C Evaporator - Ices Up
Group 64Heating and Air Conditioning
Bulletin Number
64 03 00
Woodcliff Lake, NJ
September 2000
Service Engineering
SUBJECT:
E46 Evaporator Ices-up During A/C Operation
MODEL:
E46, produced prior to November 1999
Situation:
The air output from the ventilation grills is reduced (or may even cease) after using the air conditioning for a considerable length of time. The setting of the blower speed on the IHKA control panel remains unchanged, and the blower can still be heard running. After the air conditioning system or engine has been turned off, a large amount of water condensate melts and drains from the vehicle.
The airflow is restored after the A/C system is turned off for at least 30 minutes.
Cause:
A faulty evaporator temperature sensor causes the evaporator to ice-up in air conditioning mode.
Correction:
On a customer complaint basis only, using DIS/MoDiC tester perform a functional check of the evaporator temperature sensor, and replace the sensor if found defective.
Procedure:
1. Connect vehicle to DIS/MoDiC tester.
2. Select "Diagnostic Control Unit Function", and "IHKA Heater/Automatic A/C Control"
3. Select "A/C control system".
4. Select "Evaporator temperature"
5. Select "Display"
6. With the engine switched off, and at room temperature (approx. 68 (F) read the temperature value of the evaporator temperature sensor (should be around 20 (C).
7. Then start the engine and switch the A/C system on. Set temperature on the IHKA control panel at 59 (F), and the blower to the lowest speed. After approximately 3 to 4 minutes of A/C operation, the temperature of the evaporator sensor displayed in the DIS/MoDiC should drop to at least 10(C).
8. If the values specified in step 7 are not achieved, the evaporator temperature sensor must be replaced. (If the test criteria are met, the evaporator temperature sensor is not at fault, and further diagnosis should be performed, e.g.: micro-filter, A/C compressor clutch, etc.).
The evaporator temperature sensor is located above the driver's footwell, on the left lower part of the IHKA box.
Parts Information:
Warranty Information:
Covered under the terms of the BMW New Vehicle Limited Warranty.