Removal refrigeration unit from a DAF 105 tractor is a technically complex procedure that requires not only physical strength from the mechanic, but also a deep understanding of the design of refrigeration systems. Often the reason for dismantling is a compressor breakdown, a refrigerant leak, or scheduled maintenance that cannot be carried out without removing the unit. Owners of DAF trucks value the reliability of their vehicles, but when it comes to air conditioning systems, they have to deal with nuances that are not obvious at first glance.
The process requires careful preparation of the workplace and the availability of special tools, since many fasteners could “stick” tightly during operation. It is important to understand that simply unscrewing the bolts is not enough: you need to properly drain the oil, relieve pressure in the system and disconnect the electrical connectors without damaging the wiring. Any mistake at the dismantling stage can lead to expensive repairs or the inability to start the system in the future.
In this article we will analyze in detail each stage of the work, paying attention to specific aspects of the DAF 105 design that often confuse inexperienced craftsmen. We will look at the preparation of equipment, the procedure for disconnecting lines and the features of removing a heavy unit from a niche in the cabin or frame. Compliance with the technology will allow you to complete the work efficiently and safely.
Preparation of the workplace and the necessary tools
Before starting any work with the refrigerator on the DAF 105, it is necessary to ensure safe working conditions. The truck should be parked on a flat, solid area, preferably under a canopy, so that direct sunlight does not heat the system, increasing excess pressure in it. Be sure to use wheel chocks, as you will have to apply significant force to the fasteners, and the machine’s displacement is unacceptable.
To perform dismantling efficiently, you will need a standard set of mechanic tools and specialized equipment. It is strictly prohibited to work with the refrigeration circuit without a vacuum pump and a pressure gauge station, since the release of freon into the atmosphere not only harms the environment, but also makes it impossible to check the tightness of the system after repair.
- 🔧 A set of wrenches and sockets (including extended ones for hard-to-reach places)
- 🔧 A pressure gauge station and hoses for pumping out refrigerant
- 🔧 Vacuum pump to remove residual freon and moisture
- 🔧 Containers for draining compressor oil and refrigerant
⚠️ Attention: Before starting work, be sure to check the condition of the hoses of the pressure gauge station. Cracks or abrasions can lead to injury due to high pressure or air entering the system.
Pay special attention to lighting. The niche where the refrigerator is installed on the DAF 105 is often dark, and poor visibility can cause the key to fall off or damage neighboring components. Using a headlamp or portable lamp will greatly simplify access to hidden bolts and connectors.
☑️ Preparation for dismantling
Draining the oil and releasing pressure in the system
The first technical stage is reducing the pressure in the circuit and removing working fluids. In DAF 105 systems, especially if they have been in use for a long time, the pressure may remain high even after inactivity. Relieving pressure must be done carefully, through the service ports, directing a stream of gas into a prepared container or through a pressure gauge hose into the ventilation (if this is allowed by recycling standards in your region).
After the pressure drops, it’s the oil’s turn. The compressor oil in DAF refrigerators often has a specific chemical composition (polyester or polyalphaolefin), which is hygroscopic and requires careful handling. Drain the oil through the compressor drain plug or, if the design does not allow, through the disconnected pipe, substituting a measuring container.
| Refrigerant type | Oil type | Pressure at 25°C (bar) | Marking color balloon |
|---|---|---|---|
| R134a | POE (Polyester) | 6.5 - 7.0 | Light blue |
| R404A | POE (Polyester) | 10.0 - 11.0 | Orange |
| R410A | POE/PAG | 16.0 - 17.0 | Pink |
It is important to accurately determine the type of refrigerant used, since mixing different types of oils or freons can lead to the formation of acids and compressor failure. Various installation modifications may be found on the DAF 105, so check the plate on the unit.
Why should you not mix oils?
Mixing mineral and synthetic oils (for example, POE and MO) leads to stratification of the mixture, loss of lubricating properties and the formation of solid sediment, which clogs the capillary tubes and removes the compressor from building.
Dismantling of electrical connections and wiring
The electrical part of the refrigerator on the DAF 105 is a complex network of sensors, relays and controllers. Before physically removing the unit, it is necessary to de-energize the system by disconnecting the ground on the truck battery. This is a critical step to prevent short circuits if the wire insulation is accidentally damaged during removal.
Begin by disconnecting the main wiring harness from the control unit. Connectors may be dirty or oxidized, so use contact spray to clean them before disconnecting. Carefully snap off the latches without using excessive force, as the plastic becomes brittle over time and may burst.
Pay attention to the temperature and pressure sensors. They are often located in hard-to-reach places and have thin wires. When removing the refrigerator, these wires may become stretched and break if they are not disconnected or released from the clips in advance. Test the circuit with a multimeter to make sure there are no breaks before disassembling.
- 🔌 Turn off the main fuse of the refrigeration unit
- 🔌 Remove the connectors from the solenoid valves
- 🔌 Disconnect the wires from the evaporator sensors and capacitor
- 🔌 Check the integrity of the harness insulation for chafing
Disconnecting pipelines and heat exchangers
The pipelines of the DAF 105 refrigeration unit are made of copper or aluminum and connected by soldering or using threaded fittings. Dismantling most often requires flaring or sawing off the tubes if they do not have service valves. Use a pipe cutter to obtain a clean edge, which will be useful during reassembly.
When disconnecting the condenser and evaporator, be prepared for residual gas to escape from the system. Keep plugs ready to immediately seal any open tube openings. Moisture or dust entering the copper lines is unacceptable, as this will lead to the formation of ice plugs and corrosion.
Heat exchangers on the DAF 105 can be fixed quite rigidly. Make sure all mounting brackets are removed before removing them. Sometimes it is necessary to remove part of the cabin lining or frame elements to access the rear pipes.
⚠️ Attention: When working with an open flame (burner) to solder pipes, use extreme caution. There may be flammable materials, plastic parts in the cabin, or residual oil nearby.
If the tubes are stuck, use penetrating lubricant, but avoid getting it inside the system. After disconnecting all lines, visually inspect them for cracks or severe corrosion. Deformed areas will need to be replaced.
Removing the compressor and main unit
The compressor is the heart of the refrigeration unit, and on the DAF 105 it is usually attached to the engine or a separate subframe through damper pads. Before removal, check the tension of the drive belt (if the compressor is mechanical) or the condition of the electrical connections (if it is electric). Loosen the tension mechanism and remove the belt.
Unscrew the compressor mounting bolts. Due to vibrations, they can be very tight. Use a long-handled wrench, but be careful not to strip the threads. It is better to place a stop under the compressor, since after unscrewing the last bolt it can drop sharply.
Removing the main unit (monoblock) from the DAF 105 frame requires the help of a second person or the use of a lifting mechanism. The weight of the installation can reach several tens of kilograms. Carefully lift the unit to remove it from the mounting slots and remove it from the niche.
Cleaning the seat and troubleshooting components
After removing the refrigerator, you must thoroughly clean the seat. years of operation leave behind layers of dirt, oil, and corrosion products. Use a degreaser and compressed air to clean the mounting surfaces on the DAF 105 frame. This ensures a tight fit for the new or repaired unit.
Carry out troubleshooting of the removed units. Inspect the compressor for shaft play, check the condition of the valve group. Blow the heat exchangers with compressed air in the opposite direction of flow to remove dirt from the lamellas. If oil stains are found, look for the leak.
Check the condition of the rubber seals and dampers. Over time, rubber hardens and cracks, losing its shock-absorbing properties. Replacing these cheap parts now will save you nerves and money in the future by preventing vibration and noise.
- 🧼 Clean the mounting sites from dirt and oil
- 🧼 Check the integrity of the threaded connections on the frame
- 🧼 Inspect the condition of the vibration mounts and rubber bushings
- 🧼 Measure the resistance of the electric motor windings
Assembly and initial launch of the system
Assembly is performed in the reverse order. Place the unit in place, secure the compressor and connect the pipelines. When soldering copper pipes, be sure to use nitrogen purge to prevent scale from forming inside. This rule is often ignored, but it is the scale that causes the breakdown of new compressors in a short time.
After assembly, the system must be evacuated. Connect a vacuum pump and evacuate the air until a deep vacuum is achieved (usually below 500 microns). This will remove moisture and remaining air. Then charge the system with the exact amount of refrigerant specified in the DAF specification.
Carry out the first start-up under the control of pressure gauges. Listen to the operation of the compressor: there should be no extraneous knocking or vibration. Check the temperature at the outlet of the evaporator and make sure that the refrigerator begins to get cold.
What to do if there is no cold after startup?
If the system does not cool after startup, check the operation of the condenser and evaporator fans. Make sure the thermostat is working properly and set to the correct temperature. It is also possible that the capillary tube is clogged or there is an air lock in the system, which requires repeated evacuation.
How often do you need to change the oil in a DAF compressor?
In hermetic compressors, the oil is changed only during a major overhaul or replacement of the compressor. In semi-hermetic units available for maintenance, it is recommended to change the oil every 2000-3000 engine hours or annually, depending on the intensity of operation.
Is it possible to use automobile freon in a refrigerator?
Use automobile freon (usually R134a) in stationary or transport refrigerators designed for other refrigerants (for example, R404A) are strictly prohibited. This will lead to incorrect operation of the system, overheating of the compressor and possible destruction of components due to differences in pressure and properties of oils.
Why does the compressor hum after installation?
The hum can be caused by improper installation of vibration supports, an overtightened belt (if the drive is mechanical) or water hammer if liquid oil has entered the system or refrigerant Also check the tension of the mounting bolts.
Is it necessary to flush the system when replacing a compressor?
Yes, if the old compressor burned out or chips were found in the system, flushing is required. Use a special flushing solvent or pressurized nitrogen to remove oil breakdown products and metal dust from heat exchangers and tubes.