Which tubes in the refrigerator should be cold: complete diagnostics

The question of which tubes in a working refrigerator should be cold and which should be hot often arises among owners of household appliances at the first sign of a failure. Understanding the principle of operation of the refrigeration circuit allows you to carry out initial diagnostics without calling a technician, which can save significant money. Refrigerant circulation the system is a continuous process, and the temperature of various sections of the circuit is strictly regulated by the physics of the process.

Normal operation of the unit implies a clear distribution of temperature zones on external elements. If you notice that condenser remains warm, but the freezer has stopped freezing, or, conversely, the entire body is covered with frost, this is a signal of a heat transfer problem. In this material we will analyze in detail how the system should behave in normal mode and what deviations mean.

However, there are nuances associated with the type of refrigerant and the design of the compressor. Accurate knowledge of the temperature gradient helps to distinguish a simple overload of the thermostat from a serious freon leak or blockage of the capillary system. Let's look at this mechanism step by step.

Principles of operation of the refrigeration circuit

To understand where the cold should be and where the heat should be, it is necessary to briefly consider the path of the refrigerant. The compressor compresses freon gas, turning it into a hot liquid under high pressure. This heated gas is directed to a condenser, usually located on the rear wall or sealed in the side walls of the housing. Here, heat is released into the environment.

After passing through the condenser and filter-drier, the refrigerant enters the narrow capillary tube. It is at this moment that a sharp drop in pressure occurs, and the liquid begins to actively evaporate, absorbing heat from the refrigerator chambers. This process occurs in the evaporator, which in modern models is often hidden behind plastic panels.

⚠️ Attention: The temperature of the tubes may vary depending on the ambient temperature (room temperature) and the stage of the compressor operating cycle. Do not draw final conclusions if the refrigerator has just turned on after defrosting.

Thus, we have two main sections: discharge (hot) and suction (cold). Violation of the temperature balance in these areas indicates a specific malfunction. For example, if the hot zone moves or disappears, this indicates a problem with circulation.

Heat zones: condenser and discharge tube

The first area to check is the high pressure zone. Immediately after leaving the compressor, the (discharge) tube should be noticeably hot. Depending on the model and load, its temperature can reach 50-80°C. This is normal and indicates that the compressor is working and compressing the gas.

Next, the hot refrigerant enters the condenser. In old models this is a grille at the back, in new ones it is often built into the side walls (Hot Side). The sides of the refrigerator should be warm or even hot in the upper and middle parts. If you put your hand on the side of a running unit and feel uniform heat, this is a sign of a working heat removal system.

• 🔥 Discharge tube: Very hot, goes from the compressor to the condenser.
• ☀️ The upper part of the condenser: Hot, here the gas gives off the maximum amount of heat.
• 🌡️ The lower part of the condenser: Warm or slightly hot, the freon has already cooled down and condensed into liquid.

If the condenser is cold or at room temperature, and the compressor is humming, this may indicate a lack of freon in the system or a breakdown of the compressor that does not create the required pressure. In some cases, for example, when there is a blockage, the heating zone may be very short, only at the outlet of the compressor.

Cold zones: evaporator and suction tube

Now let's move on to the question of which tubes should be cold. After passing through the capillary system and entering the evaporator, the refrigerant boils. The tube leaving the evaporator and going back to the compressor (suction) must be cold. Ideally, it even becomes covered with dew or light frost, but it should not be overgrown with a “fur coat” along the entire length to the compressor.

In systems No Frost the evaporator itself is hidden, but the principle remains the same. The cold is generated inside the evaporator unit and the air is circulated by a fan. If you open access to the evaporator (by removing the back panel in the freezer), you will see that the entire coil is evenly covered with frost or cold to the touch.

It is important to distinguish between a “just cold” and an “ice” tube. The suction line of the compressor should be cold, but not freeze through to the metal housing of the compressor. Freezing of the suction tube up to the compressor often indicates excess of refrigerant or a malfunction of the thermostat, which prevents the system from shutting down.

The uniformity of evaporator cooling is a key indicator. If in the system Direct Cool (drip) the rear wall of the refrigerator is only half covered with ice or has “bald patches”, this is an alarming sign.

Diagnostics by temperature: what means absence of cold or heat

Analysis of temperature zones allows you to determine the type of malfunction with high accuracy. Let's consider the most common scenarios that users encounter when diagnosing themselves.

If the compressor is running and humming, but all tubes are at ambient temperature (there are no cold or hot zones), this is a classic sign. freon leaks. The gas came out through a microcrack, and there is simply nothing to circulate. In this case, the refrigerator may hum around the clock, trying to gain temperature, but to no avail.

Another option: the tube at the outlet of the compressor is hot, and then (after 10-15 cm) it suddenly becomes cold or room temperature. This points to clogged capillary system. The plug (often made from moisture or oil oxidation products) does not allow the refrigerant to pass further, creating a zone of high pressure and heat in front of the plug.

⚠️ Attention: If you find that the tubes are covered with rust at the solder points or traces of oil are visible, this is an almost guaranteed leak. The oil comes out along with the gas under pressure.

It is also worth paying attention to the operation of the compressor. If it turns on for a few seconds, clicks and turns off, and the tubes do not have time to change the temperature, the problem may be in the starting relay or the motor itself, which cannot start.

Why can the tubes be colder than normal?

This can happen when operating in super-freeze mode or if there is a malfunction of the thermostat, which is “stuck” in the “on” position, forcing the compressor to work without stopping.

Features of temperature conditions in different types of refrigerators

Different designs of refrigeration units make their own adjustments to diagnostics. Owners should take these nuances into account so as not to mistake the norm for a breakdown.

In refrigerators with a system No Frost the main heat exchanger (evaporator) is located in a separate block, usually in the upper part of the freezer or behind the panel. The pipes going to and from it can be hidden by thermal insulation. Here it is important to check the temperature of the air leaving the ducts and the operation of the fan. If the fan does not spin, the evaporator will quickly freeze and the cold will stop flowing into the chambers, although the compressor may work properly.

Models with one compressor and two chambers often use a weeping evaporator in the refrigerator compartment. Here the back wall should periodically become covered with frost (“cry”) and then thaw. If the wall is dry and warm, there is no cold. If it is constantly covered with a thick layer of ice, the defrost cycle is broken or the door does not close.

• ❄️ No Frost: Checking the air flow and temperature at the outlet of the channels.
• 💧 Drip system: Visual inspection of the rear wall of the refrigeration chamber.
• 🧊 Two-compressor: Each circuit is working independently, check the temperature zones for each compressor separately.

There are also models with a “zero temperature” zone or Fresh Zone. They may have additional dampers and sensors, but the basic principle of operation of the condenser and evaporator tubes remains unchanged.

Checklist for self-checking temperature zones

Before calling the service, conduct a comprehensive check. This will help the technician more accurately navigate by phone or understand that the problem can be solved by simple adjustment.

Start with a visual inspection. Make sure the refrigerator is level, the doors close tightly, and the seals are not damaged. Then let the unit run for at least 30-40 minutes. It is pointless to take measurements before, since the system will not reach operating mode.

Touch different areas. Compare the sensations: if one side is hot and the other is cold, this is a good sign. If the temperature is the same everywhere, look for a leak or a problem with the compressor. Don't forget to check if the condenser is clogged with dust at the back, as this impairs heat transfer.

⚠️ Attention: Be careful when touching the internal elements of the refrigerator if it is connected to the network. Avoid sudden movements to avoid damaging the fragile evaporator tubes, especially in the freezer.

If after checking you come to the conclusion that the temperature regime is broken, do not rush to completely disassemble the unit. Often the problem is solved by replacing the thermostat or eliminating the door misalignment, which you can do yourself if you have the tools.

Frequently asked questions (FAQ)

Why is the top of the refrigerator hot and the bottom cold?

This is absolutely normal for most models. Hot refrigerant enters the condenser from the top, gradually cooling as it moves down. Therefore, a temperature gradient from the top to the bottom of the back wall or sides is a sign of proper circulation.

Can the entire tube from the compressor be cold?

The entire tube cannot be cold, since it consists of a discharge (hot) and a suction (cold) part. If you mean just the suction tube, then it should be cold. If it is covered with a thick layer of ice (“a fur coat”) right up to the compressor, this is a malfunction (the thermostat is faulty or there is an excess of freon).

What to do if the tubes are warm, but the refrigerator does not freeze?

Most likely, there is a refrigerant leak. The gas has come out, the compressor circulates the void, so the tubes do not heat up or cool down. It is necessary to search for leaks, solder and fill the system with freon.

Is it normal that the tubes heat up only when the refrigerator is turned on for the first time?

No. The tubes must heat up and cool down cyclically during operation. If there is heating only at start, and then disappears, perhaps the compressor does not develop the required pressure or the system is clogged.

How often do you need to check the temperature of the tubes?

There is no need to specifically check the tubes. Pay attention to them only if you notice a change in the operation of the refrigerator: it has become worse at freezing, it turns on more often, there is noise or condensation outside.