Cafe unit barely cooling: years of grease sludge on the evaporator coil
A cafe unit had been losing cooling for over a year despite quarterly servicing. The previous contractor blamed a weakening compressor and quoted a replacement. A compressor that still runs and pushes normal airflow rarely fails quietly like that, so the symptom did not fit the diagnosis.
By Team Snowflake | Reviewed 13 Apr 2026
Case summary
Daikin Wall-mounted12 years oldF&BOutram, Singapore
- Concern
- Previous contractor said compressor was weakening and quoted for replacement
- Previous advice
- Previous contractor recommended compressor replacement due to declining cooling output
- Found
- Evaporator coil completely insulated by thick grease and biofilm buildup from years of food-service operation
- Key check
- Removed front cover and inspected coil face. Fins were visibly caked with a thick layer of orange-brown sludge that general servicing had never reached
- Result
- Full cooling returned after the chemical overhaul. No compressor replacement, no parts. Given the grease-heavy kitchen, we recommended switching to six-monthly chemical overhauls. General servicing alone would not stop the same buildup from returning.
What we were told
The unit had been losing cooling gradually over the past year. Quarterly servicing was done on schedule, but each cycle brought less improvement. The previous contractor measured the system, said the compressor was losing efficiency, and quoted a replacement.
What we checked
The unit was running on arrival. Airflow from the vents felt normal in strength but warmer than expected. The compressor cycled normally, with no short-cycling, no unusual noise, and no error codes. That pattern does not match a failing compressor, which usually cycles unstably, trips on overload, or fails to start. So we removed the front panel to inspect the evaporator coil directly.
Compressor running and cycling normally. No short-cycling, no overload trips, no abnormal sound from the outdoor unit.
Airflow strength was normal, but supply air ran several degrees warmer than expected for the set point. That points to weak heat exchange, not weak airflow.
The evaporator coil fins were caked with a thick layer of orange-brown residue. It was a mix of cooking grease, dust, and biofilm built up over years in a kitchen.
The buildup ran deep into the coil. General servicing had only touched the outer layer, leaving the core of the coil blocked.
What we found
The evaporator coil had collected years of grease, dust, and biofilm through its full depth. In a cafe, airborne cooking oil settles on the wet coil and binds with dust into a sticky film that hardens over time. General servicing cleans the filters and drain pan, but it does not open the unit or wash the coil fins with chemical solution. So each quarterly service restored filter airflow while the coil stayed coated. Heat exchange declined slowly, and that decline looked just like a compressor losing capacity.
What fixed it
We recommended a full chemical overhaul instead of a compressor replacement. We dismounted the unit from the wall, stripped down the coil assembly, and applied an alkaline solution under pressure to dissolve the grease and biofilm. We also flushed the drainage system. After reassembly, we ran the unit and measured supply air temperature again. It had dropped sharply, which confirmed the coil was exchanging heat properly.
Outcome
Full cooling returned after the chemical overhaul. No compressor replacement, no parts. Given the grease-heavy kitchen, we recommended switching to six-monthly chemical overhauls. General servicing alone would not stop the same buildup from returning.
What this case teaches us
In a kitchen, grease blinds the coil before the compressor fails
- Normal airflow with warm supply air points to a coil that cannot exchange heat, not a dying compressor.
- General servicing cleans filters and the drain pan. It does not reach grease baked deep into the coil fins.
- Cooking-heavy units need chemical overhauls on a schedule. Quarterly servicing alone lets the buildup return.
Related reading
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