The appearance of condensation on the glass surfaces of a display case is a signal that cannot be ignored if you value your revenue and the quality of goods. Sweating refrigerator not only creates an untidy appearance that scares off buyers, but can also indicate serious problems in the operation of the cooling equipment. Moisture can penetrate inside the packaging of products, shortening their shelf life, and constant dampness accelerates the corrosion of metal parts of the case.
The reasons for the formation of excess moisture can be hidden either in a banal failure to comply with operating rules, or in complex technical malfunctions of the system No Frost or Static Cooling. Often, store owners try to wipe the glass with a rag, not realizing that without eliminating the root cause, condensation will appear again in a few minutes. Understanding the physics of the process and the design of your model Polair, Carboma or Ariad will help you quickly localize the problem.
In this article we will analyze the main scenarios why refrigerated display case it is covered in perspiration, and we will offer a step-by-step algorithm actions. You will learn to distinguish normal operating condensation from a sign of breakdown, and also learn how to correctly set temperature conditions for a specific type of product.
Physics of the process: why condensation forms
To effectively deal with the problem, you need to understand the basic physical principle. Condensation is the moisture contained in the air, which changes from a gaseous state to a liquid upon contact with a surface having a temperature below the dew point. In the case of a display case, this surface is the inner glass or metal side.
The air in the sales area always contains a certain amount of water vapor. When you open the door or if the seal is leaking, warm, moist air enters the chamber. When faced with cold walls or glass, it cools sharply and “gives up” water in the form of drops. The higher the humidity in the room and the greater the temperature difference, the more intense the process.
Modern models of showcases are equipped with a glass heating system, but they are designed for certain conditions. If the store is hot or the air humidification is turned on, standard heaters may not cope. Dew point displaces, and moisture settles where it should not be.
⚠️ Attention: The constant presence of water at the bottom of the display case can lead to a short circuit in the electrical lighting circuits or defrosting heating elements, if the design does not provide reliable waterproofing.
It is important to note that a small amount of condensation on the rear wall in some operating modes is normal. However, when the side windows or the front glass of the display case “cry”, interfering with the view of the product, this requires intervention.
Violation of tightness and problems with the seal
One of the most common reasons why the display case sweatsis the loss of tightness of the refrigeration circuit. The main barrier to warm air is a rubber seal (cuff) located around the perimeter of the door or lid. Over time, the rubber loses elasticity, cracks or deforms.
If the seal does not fit tightly to the body, a gap is formed through which there is a constant flow of warm air. This leads not only to excessive fogging, but also to continuous operation of the compressor, which increases energy consumption. You can check the tightness with a simple test with a sheet of paper: clamp the sheet with the door and try to pull it around the perimeter.
In places where the paper comes out too easily or, on the contrary, gets stuck tightly, most likely there is a defect. It is also worth inspecting the seal for contamination: sticky traces of food or dust may interfere with a tight fit.
- 🔍 Visual inspection: look for cracks, tears or flattening of the rubber.
- 📄 Paper test: the sheet should be pulled out with noticeable resistance along the entire perimeter.
- 🧹 Cleaning: wipe the seal with a soft cloth and soapy water to remove grease.
- 🔥 Warming up: if the rubber is simply deformed, you can gently warm it up with a hairdryer and straighten it.
In some cases, a full one is required replacing the seal. This is a consumable material, and its wear is inevitable during active use. Order original components for your model Brand or MHMas universal tapes may not provide the required fit geometry.
Malfunctions of the defrosting and drainage system
If everything is in order with the tightness, you should pay attention to the automatic defrosting system. In display cases, moisture is removed through the evaporator, where it freezes and then thaws and flows into a drainage tray. If this process is disrupted, water begins to accumulate inside the chamber and condense on the glass. No Frost The moisture is removed through the evaporator, where it freezes and then thaws and drains into a drainage tray. If this process is disrupted, water begins to accumulate inside the chamber and condense on the glass.
A common problem is clogging of the drainage hole. The melt water does not have time to escape and overflows over the edge of the tray, falling on food and glass. The cause may also be a failure of the defrost heating element or timer. In this case, the evaporator becomes overgrown with a “fur coat”, the cooling efficiency drops, and the compressor works non-stop, causing freezing and subsequent abundant thawing.
Checking the system requires care. The drainage hole should be inspected for ice plugs or debris. For cleaning, you can use a special soft wire or cable, carefully inserting it into the channel.
☑️ Diagnostics of the defrost system
If you find that the back wall of the display case is covered with a thick layer of ice, and there is water underneath it, this is a sure sign of a malfunction defrost cycle. In models such as Polair or Ariad, the defrost sensor often fails, which does not give a command to turn on the heater.
⚠️ Attention: Do not try to break off the ice with a knife or sharp objects - there is a high risk of damaging the evaporator or puncturing the refrigerant tubes, which will lead to expensive repairs.
The influence of the external environment and the placement of equipment
The location of the refrigerated display case plays a critical role in the formation of condensation. If the equipment is installed in direct sunlight or next to heating devices, the thermal load on the glass increases many times over. In this case, even a working glass heating system may not cope.
It is also important to take into account the presence of drafts. A flow of cold air from an air conditioner or an open store door directed directly at a display case can create local areas of glass overcooling, causing dew to form. An incorrect gap between the back wall of the display case and the wall of the room disrupts the air circulation around the condenser.
The technical characteristics of the room also matter. Supermarkets with high ceilings and humidifiers may have high humidity levels. Such conditions require display cases with enhanced glass heating or additional thermal curtains.
- ☀️ Avoid direct sunlight falling on the display case.
- ❄️ Do not install equipment in the area of air conditioning.
- 🌡️ Maintain a distance from the walls (minimum 30-50 cm) for ventilation.
- 🚪 Minimize the time the doors are opened on hot days.
If it is impossible to move the display case, consider installing additional screens or changing the direction of air flow in the sales area. Sometimes a simple solution is to adjust the operation of the general ventilation system.
How does the temperature in the sales area affect the operation of the display case?
Each degree of temperature increase in the sales area increases the load on the compressor and the glass heating system. At temperatures above +25°C, standard display cases can work with overload, which leads to fogging.
Loading and operating errors
Often the reason the refrigerator sweatsis incorrect loading of products. If goods are stacked against the back wall or side panels, they block the circulation channels. Cold air cannot be evenly distributed throughout the chamber, “warm pockets” are formed, where condensation falls.
It is especially critical not to close the air intake line (usually located in the upper part of the back wall or under the shelves). Impaired circulation leads to temperature sensors reading incorrect data and the compressor operating mode is disrupted. Products in the depths may freeze, and near glass they may deteriorate from moisture.
It is also worth monitoring the temperature of the loaded products. Placing warm goods in the display case is strictly prohibited. A sharp jump in temperature and humidity inside the chamber is guaranteed to lead to fogging of the glass and increased load on the unit.
Follow the “maximum load” rule: do not place products above the level LOAD LINEif such markings are present on the glass or inside the chamber. Exceeding this level disrupts the operation of the air curtain in open display cases.
| Parameter | Normal | Violation | Result |
|---|---|---|---|
| Filling the volume | Up to the loading line | Above the line | Air curtain failure, condensation |
| Gap at the walls | 3-5 cm | Close | Lack of circulation, local overheating |
| Product temperature | Chilled | Warm/Hot | Sharp jump in humidity, ice |
| Cleanliness of channels | Free | Closed with packaging | Incorrect operation of sensors |
Regular revision of the display of goods is not only a matter of aesthetics, but also a technical necessity for the long life of the equipment. Properly arranged products spoil less and do not create excess moisture.
Technical faults: refrigerant and compressor
If all of the above reasons are excluded, the problem may lie in the “heart” of the refrigerator. A refrigerant (freon) leak leads to a decrease in cooling efficiency. The compressor starts to work continuously, trying to gain temperature, but cannot. This causes severe freezing of the evaporator, which then, during stop cycles, produces a lot of water.
Another option is a malfunction of the compressor itself or the start relay. If the unit hums but does not start, or operates intermittently, the temperature regime is disturbed. In such cases, not just condensation, but ice or, conversely, a complete absence of cold in humid air may appear on the glass.
Diagnostics of such problems requires special equipment: pressure gauges to check the pressure in the system, leak detectors and electrical testers. It is impossible to fix a freon leak on your own without a vacuum cleaner and a filling station.
⚠️ Attention: If you hear hissing or see oily spots on the tubes at the back of the display case, immediately unplug the equipment and call a technician. Working with refrigerant requires a license and compliance with safety regulations.
In modern electronically controlled display cases, the cause may be a controller failure. Incorrect readings of temperature or humidity sensors lead to incorrect activation of glass heating elements or fans.
Prevention and setting parameters
In order for the question “why the display case is sweating” to arise as rarely as possible, it is necessary to implement regular maintenance. Scheduled cleaning of the condenser from dust, checking the condition of the seals and monitoring the operation of the fans will extend the service life of the equipment.
It is important to correctly set the temperature conditions in the controller. Different food groups (meat, dairy, vegetables) require different temperatures. Setting too low values unnecessarily leads to excessive cooling of the glass and dew.
Use the capabilities of modern controllers Carel or Dixell. Many of them have a “Time Defrost” or “Counter Defrost” mode, which can be optimized for current operating conditions. Also check the delay settings for turning on the fans after defrosting - this prevents the release of moist air onto the glass.
- 📅 Weekly: washing the display case and checking the water flow.
- 📅 Monthly: cleaning the condenser and checking the seals.
- 📅 Quarterly: checking the operation Heating elements and calibration of sensors.
- 📅 Annually: full diagnostics of the refrigeration circuit by a specialist.
Timely prevention is cheaper than repairing or replacing damaged products. Keep an eye on the condition of your equipment, and it will delight you with transparent glass and stable cold.
Is it possible to wipe foggy glass with alcohol?
The use of alcohol or special antifogs (anti-foggers) gives a temporary effect, creating a film that spreads moisture. However, this does not solve the problem, but only masks it. In addition, harsh chemicals can damage the glass coating or the plastic casing of the display case. It is better to eliminate the cause, not the effect.
Why does the display case sweat only in the morning?
This may be due to the night mode of operation (if the display case is switched to energy saving mode and the glass temperature drops) or with a sharp temperature change when the store opens, when cold air from the street enters the room and encounters equipment heated up overnight.
How often should the seal be changed?
The service life of the seal depends on the intensity of door opening and cleaning conditions. On average, in high-traffic supermarkets, replacements are made once every 2-3 years. In small shops with careful operation, it can last 5 years or more.
Does the type of glass affect fogging?
Yes, double-glazed windows with argon or a special low-emission coating fog up much less often than single glasses. If the problem is critical, consider upgrading the glazing of the display case.