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REFRIGERATION

Troubleshooting

Condensation on glass doors

Condensation forms when warm, humid air touches a surface colder than its dew point. On a glass-door cooler, the outer glass sits close to cabinet temperature, so in monsoon conditions in Mumbai, Kolkata or Chennai the outside of the door can mist or even run with water. Double or triple glazing, low-emissivity coatings and in some units heated glass or frame heaters are used to keep the outer pane warmer. When the conditions exceed what the door is designed for, or one of those features fails, fogging starts. Fog inside the cabinet is a different problem and usually points to warm air getting in.

First, check these

  1. Note which side of the glass is fogged. Outside means room humidity is high or the glass is too cold; inside means warm air is leaking in or the door is opened very often.
  2. Check whether an air conditioner, fan or open shop door blows humid air directly onto the glass.
  3. Check the door closes and seals fully. A door that rests slightly open fogs fast.
  4. If the unit has an anti-condensation or energy-saving switch, check whether it has been set to off.
  5. Check the setpoint. Running colder than needed makes the glass colder too.

Likely causes

  1. 1. Very high room humidity

    You can check this

    Signs: Outside fogging that comes and goes with the weather, worst in monsoon mornings or near the shopfront.

    Fix: Reduce humidity where possible, keep the shop door closed if air-conditioned, move the unit away from the entrance, and wipe the glass with a dry cloth. Some fogging in extreme humidity is within design.

  2. 2. Anti-condensation heater switched off or failed

    Technician job

    Signs: Glass or frame much colder than usual; fogging started suddenly; a switch or controller setting for heaters is off.

    Fix: Turn the heater function on if it has been switched off. If it is on but the frame stays cold, a technician needs to check the heater circuit.

  3. 3. Door not closing or gasket leaking

    You can check this

    Signs: Fog inside the glass, frost along the gasket, door self-closer weak.

    Fix: Clean the gasket, check hinges and the self-closing mechanism, and replace a damaged gasket.

  4. 4. Very frequent door openings

    You can check this

    Signs: Fog on the inside of the glass that clears slowly after each opening; worst during evening rush in a busy shop.

    Fix: Fog inside is warm air rushing in. Group restocking into one session, keep doors shut between customers, and avoid propping doors open while loading crates.

  5. 5. Setpoint lower than needed

    You can check this

    Signs: Cabinet much colder than the product needs, such as beverages held at +1 °C.

    Fix: Run beverage coolers at a sensible temperature for the product. A few degrees warmer reduces glass sweating and energy use.

  6. 6. Glazing seal failure

    Technician job

    Signs: Fog or droplets trapped between the panes that cannot be wiped away from either side.

    Fix: The sealed glass unit has lost its seal and needs replacing. Contact your service provider.

When to call a technician

Call for service if fogging appears between the panes, if the glass or frame stays cold with heaters switched on, or if the door will not close properly after cleaning and adjustment. Persistent heavy condensation can drip onto floors and corrode frames, so do not ignore it in coastal locations.

Isolate power before cleaning around door frames or touching any heater wiring. Do not open control panels. Repairs to refrigeration components, especially on hydrocarbon (R290 or R600a) units, are for trained technicians only.

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