Fuel - Engine Surges/Hesitates With A/C Switched ON
85bmw05GROUP 13 Engine - Electrical
Bulletin Number 13 04 85 (1036) Page 1
Montvale, NJ May 1985 Technical Dept.
SUBJECT: Engine surging - A/C compressor clutch rapidly engaging and disengaging
MODELS: 3-Series (E 30) 5-Series (E 28) 6-Series (E 24) 7-Series (E 23)
Complaint: Engine surges/hesitates with A/C switched "on" or idle fluctuates with A/C switched "on" and at the same time, compressor clutch cuts "on and off" too often.
Problem: The A/C system may be overcharged. The excessive FREONS charge causes the high pressure cut-out switch to open and the compressor clutch to disengage. Once the system pressure has dropped the high pressure switch will then close engaging the clutch.
Correction: Perform the following repairs on ALL cars at PDI and on cars sold when they come in for service, or when you receive a customer complaint.
NOTE: Perform these checks before troubleshooting the idle control system for an idle fluctuation complaint.
1. Check the A/C refrigerant capacity label on the car. If you find a 1300 grams label on a 535i, 524td, 318i, or 325e, this is an indication the system is overcharged. A more complete listing of correct labels is given in SI bulletin 64 05 85 (1038).
2. Replace the label with the "correct" one.
3. Engage the A/C. Turn the temperature selector to the maximum cooling position. Turn the blower fan to speed position "1". Run engine at 2000 RPM. If the compressor cycles normally, do not proceed any further. However, if the compressor cycles rapidly, continue with steps 4, 5 and 6.
4. Observing safety precautions, (with engine speed at 2000 RPM) slowly discharge FREON from the A/C system until bubbles begin to appear in the sight glass.
5. Add just enough FREON until bubbles just disappear in the sight glass.
6. Verify that the condition has been corrected.
Warranty
Status: Reimburseable under the provisions of the applicable new car warranty.
Defect code: 64 50 00 77 00
Labor Allowance: 4 FRU WT
Labor Operation: 00 000 00