The modern rhythm of life and the development of logistics dictate their conditions, turning a car from a means of transportation into a full-fledged mobile warehouse. Refrigeration unit for a car ceased to be the prerogative of only big business; today it is an indispensable tool for small businesses, delivery of food, flowers and even medicine. Properly selected equipment allows you to maintain the presentation of products throughout the entire journey, regardless of external temperature conditions.
However, the process of integrating climate control technology into the vehicle body requires a deep understanding of the thermodynamics and features of the vehicle’s electrical equipment. Errors at the design or installation stage can lead to failure of both the installation itself and the car engine. In this article we will analyze in detail all aspects of selection, installation and operation. refrigerated trucksso that your equipment works like a clock.
Before you go to the store to buy equipment, you need to clearly define the tasks that your refrigeration unit will solve. The temperature conditions of cargo storage directly dictate the choice of compressor and refrigerant type. For example, transporting ice cream requires deep freezing down to -20°C, while for fresh vegetables it is enough to maintain a temperature of about 0...+5°C. An incorrect choice of installation class will lead either to damage to the cargo or to excessive consumption of fuel and resources.
Classification and types of refrigeration units
The market for climate control equipment for transport offers many solutions, each of which has its own technical features. The main division occurs according to the type of compressor drive, which is the heart of the entire system. Diesel units equipped with their own internal combustion engine, which makes them completely autonomous. They do not depend on the car engine, can operate when the engine is turned off, and are often used in long-haul transportation.
The second popular option is electrical installations, operating from the vehicle’s on-board network (12V or 24V) or from an external 220V network. Such models are quieter, more environmentally friendly and easier to maintain, but their operation directly depends on the battery charge and the operation of the generator. There are also combination models that can switch between power sources, providing maximum flexibility in operation.
The third type is installations powered by a car engine through a belt drive. They are compact and do not require separate fuel, but cooling occurs only when the machine engine is running. To choose the optimal solution, it is important to consider not only the budget, but also the specifics of the routes.
- ❄️ Autonomous diesel: powerful, operate independently of the car, but are noisy and require separate fuel.
- ⚡ Electrical (12/24V): quiet, easy to install, depend on the condition of the car's battery.
- 🔗 From the motor shaft: economical, but do not work when parked without starting the engine.
When choosing, you should also pay attention to the refrigerant. Modern systems are increasingly switching to low global warming potential freons, such as R134a or R404A. The use of obsolete gases may be restricted by law in a number of countries, so purchasing equipment "for growth" would be a smart move.
Power calculation and body preparation
The efficiency of a refrigeration unit depends 80% on the quality of the body's thermal insulation. Even the most powerful compressor will not be able to maintain the temperature if heat flows through the walls of the van faster than the system can remove it. Thermal conductivity materials is a key parameter that you need to look at when ordering a van or converting an existing one.
To calculate the required cooling capacity, the volume of the body, the desired temperature inside and the maximum temperature outside are taken into account. It is also important to consider the frequency of opening the doors: the more often you load goods, the more heat gets inside. Engineers recommend taking equipment with a power reserve of about 20-30% so that the system does not constantly operate at the limit of its capabilities.
When calculating power, take into account the “heat gain” from people: each loader entering the body introduces a significant amount of heat, which requires additional time to restore the temperature.
Insulation materials must be moisture resistant, since condensation is the main enemy of thermal insulation. Polyurethane foam (PPU) and extruded polystyrene foam (XPS) have proven themselves to be the best solutions due to their low hygroscopicity and high insulating properties. The lining is usually made of food-grade plastics or stainless steel.
| Cargo type | Temperature | Recommended power reserve |
|---|---|---|
| Frozen foods | from -18°C and below | High (25-30%) |
| Chilled meat/fish | -2°C to +4°C | Average (15-20%) |
| Vegetables and fruits | from 0°C to +10°C | Low (10-15%) |
| Flowers | from +2°C to +8°C | Average (20%) |
Don't forget about the air channels. Cold air should circulate throughout the entire volume of the body, washing the cargo from all sides. Lack of proper airflow will lead to the formation of “warm pockets” where the product will begin to deteriorate, even if the sensor on the evaporator shows normal.
Connection and electrical diagrams
Installation of the electrical part is the most critical stage where problems most often arise. Wire cross-section must strictly correspond to the current consumption of the installation. The use of thin wires will lead to their heating, a drop in voltage at the compressor terminals and, as a result, failure of the electronics or fire.
The connection must be made through a separate fuse installed as close as possible to the battery. This will protect the wiring in case of a short circuit. For electrical installations, the condition of the battery is critical: a deep discharge can kill a conventional starter battery in a few cycles.
⚠️ Attention: Never connect a powerful refrigeration unit directly to the vehicle's standard wiring without installing an additional relay and fuse. Standard circuits are not designed for long-term high current consumption.
For systems powered by a vehicle engine, it is important to set the voltage thresholds correctly. Charge control relay should shut down the unit if the voltage drops below 12.5V (for 12V systems) to leave a charge to start the engine. Otherwise, in the morning you risk finding a car with a dead battery.
☑️ Electrical check before starting
In complex systems, it may be necessary to install a second battery (AGM or GEL), which will only be responsible for powering the refrigeration equipment. This is especially true for long-term parking with the unit running.
Equipment installation process
Installing a refrigeration unit on a body requires adherence to fastening technology. Vibrations generated during movement should not be transmitted to the compressor and pipelines. Vibration isolation - a prerequisite for the longevity of the system. Fasteners must be treated with anti-corrosion compounds.
Installation of the evaporator inside the body must ensure free flow of air. The distance from the load to the ceiling and to the rear wall of the evaporator must be at least 15-20 cm. Violation of this rule will block circulation, and the unit will run idle, consuming fuel or electricity, but not cooling the load.
The pipelines connecting the external condenser and the internal evaporator must be carefully insulated. Loss of cold in the main section reduces the overall efficiency of the system. All connections must be checked for leaks using a leak detector or soap solution.
The nuances of soldering copper tubes
When soldering copper piping, be sure to use nitrogen purge. Copper oxides formed inside the pipe when heated without gas protection can clog the capillary tube or expansion valve, leading to costly repairs.
After physical installation, the system is evacuated. This is a critical step to remove moisture and air from the circuit. Residual moisture in the system turns to ice and clogs the throttle, and also reacts with the oil and refrigerant to form acid, which destroys the compressor from the inside.
Operation and typical malfunctions
During operation, the owner may encounter a number of typical problems. The most common problem is insufficient cooling. The reasons may be trivial: the condenser (external radiator) is dirty, which has stopped giving off heat to the atmosphere. Regular washing applying a radiator under pressure (carefully so as not to bend the lamellas) solves 90% of such problems.
Another common problem is evaporator freezing. This happens if there is moisture in the system or the automatic defrost system is not working. The ice coat blocks the air flow, and the temperature in the body rises. In such cases, it is necessary to stop the installation and allow the ice to melt, and then look for the cause of moisture ingress.
- 🔊 Extraneous noise: may indicate worn fan bearings or problems with the compressor.
- 💧 Condensate leak: check the drainage tube, it could be clogged with dirt or frozen.
- 📉 Frequent on/off: a sign of a malfunctioning thermostat or lack of refrigerant.
Monitor the indicators on the control panel. Modern controllers such as Danfoss or Thermo King, issue error codes that greatly simplify diagnostics. Ignoring alarms may result in complete loss of cargo.
⚠️ Attention: If you hear gas hissing or see oil stains on the connections, turn off the unit immediately. Operating a compressor with a freon leak without oil will cause it to instantly jam.
Maintenance and seasonal storage
In order for a refrigeration unit to serve for a long time, it needs regular maintenance. Once a season (or every 500 operating hours), it is recommended to check the tension of the belts, the condition of the electrical contacts and the cleanliness of the heat exchangers. Lubrication of moving parts There will also be no need for fans.
In winter, if the unit is not in use, it is advisable to preserve it: disconnect the battery, cover the unit with a protective cover from snow and reagents. If the equipment is operated in winter, make sure that snow porridge does not clog the condenser intake holes.
Regular maintenance is cheaper than emergency repairs or replacing a burnt out compressor. Prevention takes 1-2 hours, but saves thousands of rubles.
When seasonally storing trucks with installations, it is important to periodically (once a month) run the system for 15-20 minutes. This will allow you to circulate oil through the system, lubricate the compressor seals and check the functionality of the electronics. Prolonged downtime without starting can lead to souring of the valves.
Is it possible to install a refrigeration unit yourself in a garage?
Theoretically, this is possible if you have skills in working with electricity, metal and an understanding of the principles of the refrigeration cycle. However, to fill the system with freon and vacuum it will still require special equipment (vacuum pump, pressure gauge station, scales), which is unprofitable to buy just once. It is better to order hardware and installation from professionals.
How much fuel does a diesel refrigeration unit consume?
Consumption depends on the power of the installation and the ambient temperature. On average, small units consume 0.5–1 liters per hour, medium ones - 1–2 liters, and powerful mainline refrigerators can consume up to 3-4 liters of diesel per hour when actively working to lower the temperature.
How often does the refrigerant in the system need to be changed?
The refrigerant (freon) is the working fluid in a closed circuit and is not consumed during operation. If the system is sealed, refilling is only required when repairs or leaks occur. In a normally operating installation, freon lasts for decades without replacement.
Which is better: a used unit or a new one?
Buying a used unit is only justified if you understand refrigeration technology and can check the residual life of the compressor. Repairs to older systems often exceed their cost. For a business where cargo reliability is important, it is always more profitable to purchase new equipment with a guarantee.