Polo MK4 AC Noise: Diagnosis & Repair Guide (Solution)

Mitsubishi Polo MJ 2002: Noise may occur when the air conditioning is turned on.

Affected vehicle identification numbers (VINs):
Bis Fg. No. 9N 3Y 090 000
Bis Fg. No. 9N 3D 070 000


Definition:
These are described as whining or wind-like noises, or also as the operating noise of the pump for the power steering system.

Cause.
If the hissing sound after turning off the air conditioner is no longer audible, then the expansion valve may be the cause. During the calibration of the expansion valve, there were tolerances that were too large.

Solution.
In case of a defect, please install an expansion valve with part number 6Q0 820 679 A.