Noisier and weaker after chemical wash: blower off-centre

The aircon cooled well before the chemical servicing. Afterward, the airflow felt weaker and a soft rubbing noise appeared during operation. When a unit performs worse right after a service, the reassembly is the first place to look, not a failing part.

By Team Snowflake | Updated 3 Mar 2026

Case summary

Panasonic Wall-mounted5 years oldHDBSerangoon, Singapore

Concern: Unclear whether the service had damaged the blower motor, or whether a part had started failing on its own.
Found: Blower wheel reassembled off-centre on its shaft after chemical servicing
Key check: Inspected the blower wheel position and shaft clearance for anything disturbed during reassembly
Result: The rubbing noise stopped and the airflow returned to its pre-service strength. Both symptoms traced back to the wheel's position on the shaft, not to any part damaged during the wash.

What we were told

The aircon worked fine before the chemical servicing. Afterward, a soft rubbing noise appeared during operation and the airflow felt noticeably weaker. The servicing company was called back but insisted the work had been done correctly.

What we checked

When performance gets worse right after a service, the reassembly is the first place to look, not a failing part. We opened the indoor unit and checked every part a chemical wash disturbs: the blower wheel, its shaft seating, the housing clips, and the filter frame. The rubbing noise was the first clue, since it changed with fan speed rather than staying constant.

Airflow felt weaker at the grille than before the service, without any drop in cooling temperature.
A soft rubbing noise came and went with fan speed, rather than staying constant like a motor fault.
The blower wheel sat slightly off its shaft centre, close enough to brush the housing at points in its rotation.
The shaft screw was snug but had not been tightened against the centred mark on the shaft.

What we found

The blower wheel was refitted slightly off-centre on its shaft during the chemical wash reassembly. An off-centre wheel brushes the housing at certain points in its rotation, which produced the soft rubbing noise. The same off-centre position also disrupts the even airflow path through the wheel, cutting the volume of air reaching the room. Neither fault came from a worn part. Both traced back to how the wheel was seated when the unit was closed up.

What fixed it

We recentred the blower wheel on its shaft, aligning it against the marked centre point, and tightened the shaft screw firmly. We then spun the wheel by hand to confirm it cleared the housing at every point in its rotation, with no contact anywhere. No parts were needed. The wheel was undamaged, just seated wrong. We ran the unit for an extended cycle and confirmed the rubbing noise was gone and the airflow had returned to its pre-service strength.

Outcome

The rubbing noise stopped and the airflow returned to its pre-service strength. Both symptoms traced back to the wheel's position on the shaft, not to any part damaged during the wash.

What this case teaches us

Noise and weaker air after one service usually point back to the reassembly

When airflow drops and a soft noise appears right after a wash, suspect the reassembly before suspecting a failing part.
An off-centre blower wheel brushes the housing at points in its rotation. It costs nothing to refit, once found.
Tell us the service date and whether the noise changes with fan speed. That pattern points straight at the blower wheel.

Questions this case answers

Aircon noisier and weaker after a chemical wash: what went wrong?

Something was refitted out of position when the unit was closed up. Here the blower wheel sat slightly off its shaft centre, close enough to brush the housing at points in its rotation. That contact made the soft rubbing noise, and the same off-centre position disturbed the airflow path and cut the volume of air reaching the room.

Soft rubbing noise from the indoor unit: is the motor damaged?

A noise that rises and falls with fan speed follows the wheel, not the motor. A motor fault tends to hold a constant character instead. That was the first clue on this unit, and the shaft screw was then found snug but never tightened against the centred mark on the shaft.

Can this be fixed without new parts?

It was here. The wheel was recentred on its shaft against the marked point and the screw was tightened firmly, then the wheel was spun by hand to confirm it cleared the housing everywhere in its rotation. Nothing was damaged, only seated wrong. An extended run confirmed the noise had gone and the airflow was back to its pre-service strength.

What should I tell the next technician about a post-service problem?

The date of the service, what was done, and whether the noise changes with fan speed. Those three details point straight at the parts a wash disturbs: the blower wheel, its shaft seating, the housing clips and the filter frame. Without them the search starts wide, and a reassembly slip is easy to mistake for a failing component.

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Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.

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