Quick answer: The five most common reasons a refrigerated van stops cooling are refrigerant loss, a dirty or blocked condenser, a failed door seal, a compressor fault, or an electrical failure. Of these, a dirty condenser is the only one a driver can address on the road.
The refrigeration unit was working at the start of the day. Now the temperature inside the cargo space is rising and the load on board is at risk. The instinct is to keep driving and hope the unit recovers. It will not.
This guide gives you a systematic way to identify what is most likely wrong, what to check without tools, and when to stop the vehicle and call for help.
Check these four things first
- Is the unit turned on and set to the correct temperature? Confirm the cab controller shows the correct setpoint. A setpoint that has been accidentally changed to +15°C explains a cargo space at +12°C immediately.
- Is the condenser airflow blocked? The condenser unit on the roof or front wall needs clear airflow to release heat. A tarpaulin, loading dock overhang, or parked position against a wall can restrict airflow enough to cause cooling loss. Move the vehicle to an open area and wait 10 minutes.
- Are the cargo doors sealed? An incompletely closed door, even by a few millimetres, allows warm air to enter continuously. Check the door latch is engaged and the seal compresses evenly around the full perimeter.
- Is the vehicle engine running? On a direct drive unit, the engine drives the compressor. If the engine is off, the unit is off. If the unit appears to be running (fans operating) but not cooling on a direct drive setup, the compressor is not being driven.
Symptom-cause-action table
| Symptom | Most Likely Cause | Action |
|---|---|---|
| Unit not starting at all | Electrical fault, blown fuse, failed relay | Check fuse box; call technician if fuse is intact |
| Fans running but no cooling | Refrigerant loss, compressor failure | Call ARCtick technician — do not reload cargo |
| Cooling but not reaching setpoint | Low refrigerant, dirty condenser, door seal failure | Clean condenser; call technician if persists |
| Short-cycling (starts and stops repeatedly) | Pressure fault, blocked filter drier, refrigerant issue | Stop operating; call technician |
| Heavy ice on evaporator coils | Defrost fault, door seal failure, blocked drain | Manual defrost (turn unit off 30 min); call technician |
| Cargo warming gradually over the run | Door opened too frequently, failing insulation, low refrigerant | Check door seals and insulation panels; call technician |
| Temperature alarm will not clear | Underlying fault not resolved | Do not reset and ignore; call technician |
Refrigerant loss: the most common cause of cooling failure
Refrigerant does not evaporate or deplete through normal operation. A unit with lower refrigerant than it should have has a leak. The most common leak locations are refrigerant line fittings, the compressor shaft seal, and any point where a line passes through the van body.
The signs of a refrigerant leak are: gradual cooling capacity loss over days or weeks, an oily residue around line fittings or the compressor body, and a unit that runs continuously without reaching setpoint. A sudden and complete loss of cooling that was not preceded by gradual decline points more to a compressor or electrical failure than a refrigerant leak.
Refrigerant handling is restricted by law to ARCtick-licensed technicians under the Australian Refrigeration Council scheme. Do not attempt to add refrigerant without a technician. Adding refrigerant to a leaking system without sealing the leak is a waste of money and does not fix the problem.
Condenser coil condition: the check you can do on the road
The condenser coils release heat from the refrigeration cycle to the outside air. If the coils are clogged with road dust, insect debris, or condensed dirt from the engine bay, they cannot release heat efficiently. The unit runs but cannot achieve setpoint.
On a van with an accessible condenser unit, visually inspect the coil fins. If they are visibly blocked with debris, compressed air from a service station can clear enough to restore partial cooling. A full coil clean at a workshop uses a specific cleaning agent and water rinse. If the coil is clean and the unit still cannot reach setpoint, the problem is elsewhere.
When to stop and call for help
Stop loading cargo and call Auto Frigo on 0486 023 788 when:
- The unit runs but cannot get below +10°C after 30 minutes in an unloaded van on a moderate day
- The compressor makes a new grinding, rattling, or knocking noise
- The temperature alarm returns within minutes of being reset
- There is a visible oil residue around any refrigerant fitting or line
- The unit short-cycles more than 3 times in a 15-minute period
Auto Frigo provides emergency call-out within 200km of Melbourne. For scheduled repair bookings at Somerton or Dandenong South, use the online booking system. For the full list of common faults and repair costs, see the transport refrigeration repairs guide.
Frequently Asked Questions
Can a refrigerated van cool down faster if I turn the unit to maximum?
Setting the setpoint lower than required does not make the unit cool faster. The compressor runs at the same capacity regardless. What changes the speed of temperature pulldown is the thermal mass of the cargo, the insulation quality, and the ambient temperature outside. Pre-cooling an empty van for 20 to 30 minutes before loading is far more effective than adjusting the setpoint after loading.
Why does my van cool down at night but not in the afternoon?
Is it safe to carry cargo if the unit is running but the temperature is 2 degrees above setpoint?
How quickly can a refrigerated van lose its temperature if the unit stops completely?
A properly insulated medium van with a full chilled load will rise approximately 1°C to 2°C per hour from the cargo thermal mass in moderate ambient conditions. In summer at 38°C ambient, this rate increases significantly, particularly with frequent door opens. A van at 3°C with a stopped unit can reach 8°C in 2 to 4 hours in Melbourne summer conditions. Do not wait to see what happens.
My van is cooling but there is condensation dripping inside the cargo space. Is this a fault?
Some condensation on the evaporator is normal. Condensation dripping from the evaporator unit or pooling on the floor is not normal and indicates the drain line is blocked. Blocked drains allow water to accumulate, which can freeze on the evaporator and restrict airflow. At the next service, the drain line should be cleared. If water is pooling heavily between services, the drain should be cleared earlier.
