A/C System - Diagnostic Hints
GROUP 64
Heating and Air Conditioning
Bulletin Number
64 05 99
Woodcliff Lake, NJ
September 1999
Product Engineering
SUBJECT:
DIAGNOSIS HINT: E38, E39 A/C Inoperative
MODEL:
E38, E39 produced 9/98 and later
Situation:
Complaint of A/C not functioning. The following malfunctions may be encountered:
-- A/C compressor always "on".
-- Auxiliary fan does not switch on.
-- High side pressure reading above 300 lbs. and compressor pressure relief valve may have been activated.
Cause:
IHKA possibly not coded correctly.
Correction:
Recode the IHKA with CD 18.0 or higher.
Procedure:
To verify the A/C operation:
1. Start the engine and turn the A/C "off".
2. Visually inspect the A/C compressor to determine if the clutch is engaged.
3. If the compressor is always engaged, recode the IHKA module. After coding, check for proper A/C operation.
If the compressor is not engaged after coding, shut the engine off and connect the A/C manifold gauges. Start the engine and activate the A/C.
Set the temperature to 60 F.
4. Check the system pressure. If the pressure is low, the refrigerant may have been lost through the compressor relief valve.
5. Recover the remaining refrigerant and recharge to the specified quantity. Check the system for proper operation and refrigerant leaks. If the
system is not functioning properly, further diagnosis is required.
Warranty Information: For information only.
