Choosing a transport refrigeration unit without understanding the differences between types is like buying a commercial oven without knowing the difference between convection and deck. The hardware looks similar. The applications are not.
There are four main types used across vans, trucks, and trailers in Australia. Each suits a different operating profile.
Direct Drive Units
A direct drive unit takes its power from the vehicle’s engine via a belt or a power take-off (PTO). The compressor runs when the engine runs. When the engine stops, so does the refrigeration.
This is the most common setup for delivery vans and light trucks making frequent short stops. It is mechanically simpler, lighter, and less expensive to buy and maintain than alternatives. The trade-off is that it offers no cooling during extended engine-off periods such as overnight loading bays.
Daikin’s van range, installed by Auto Frigo, includes direct drive units suited to vehicles from small cargo vans through to medium trucks. The Daikin V-Series handles cargo spaces up to approximately 20m³ and holds temperatures from -25°C to +30°C, covering both chilled and frozen loads.
Electric Standby Units
An electric standby unit runs on 240V shore power when the vehicle is parked at a depot or dock, and switches to the vehicle engine when moving. This keeps the cargo space cold overnight without idling the engine.
For businesses that pre-load vehicles the night before, or hold products in a van between shifts, standby capability is not optional. It is a practical requirement. Running a diesel engine at idle for 8 hours to maintain temperature costs roughly AUD $15 to $25 in fuel and adds engine wear. A standby connection eliminates that cost.
Self-Powered Units
A self-powered unit carries its own small diesel or petrol engine. It operates completely independently of the vehicle. The vehicle can be switched off, even broken down, and the refrigeration keeps running.
These are standard on long-haul trucks and refrigerated trailers. For metro delivery use, they are heavier and more expensive than direct drive alternatives, but for any cargo that cannot tolerate a break in cooling (pharmaceuticals, certain biologics, premium seafood), the independence is the point.
Thermo King, Carrier Transicold, and Daikin all manufacture self-powered units for the Australian market.
Multi-Temperature Units
A multi-temperature unit divides the cargo space into two or three separate zones, each held at a different temperature. A single van can carry frozen (-18°C), chilled (+2°C), and ambient sections simultaneously.
This matters for food service distributors who deliver to hospitality venues with mixed orders, or grocery suppliers handling both fresh and frozen lines in one run. Without multi-temperature capability, they need two vehicles. With it, they need one.
The installation is more involved. It requires bulkheads, separate evaporators for each zone, and careful electrical commissioning. Auto Frigo builds multi-temperature conversions for both vans and medium trucks. Build time is typically 5 to 8 days depending on the vehicle size and zone configuration.
EV-Compatible Units
Electric vehicle refrigeration is a growing category in Australia. Traditional direct-drive units cannot connect to an EV’s drivetrain. EV-compatible units draw from the vehicle’s high-voltage battery pack or a dedicated auxiliary battery system.
Daikin’s ZERO series is designed specifically for zero-emission vehicles. It runs entirely on electric power with no diesel engine. For businesses with sustainability targets or operating in low-emission zones, this is the only type that works.
The main practical limitation is range impact. Running a refrigeration unit from the same battery that drives the vehicle shortens the driving range, typically by 15% to 25% depending on ambient temperature and cargo volume. Fleet managers need to account for this in route planning.
Choosing The Right Type
Three questions narrow the decision:
- Does the vehicle need to stay cold with the engine off?
If yes, eliminate direct drive. Choose standby, self-powered, or EV-compatible depending on the use case. - Does the vehicle carry more than one temperature product?
If yes, look at multi-temperature configurations. - Is the vehicle electric or hybrid?
If yes, only EV-compatible units apply.
Beyond these filters, capacity matters. A unit specified too small for the cargo space will run constantly and still fail to hold temperature on hot days. Auto Frigo engineers specify units based on the insulated cargo volume, ambient temperature range for the operating routes, and door-open frequency not just vehicle size.
FAQs
Can I upgrade a direct drive van to standby later?
Yes, most direct drive units designed for standby have a connection port. The upgrade requires an auto-changeover switch and a shore power socket fitted to the van. Auto Frigo can retrofit this on most Daikin and compatible units already installed.
How long do transport refrigeration units last?
A well-maintained direct drive unit in a delivery van typically lasts 8 to 12 years. Self-powered truck units running daily long-haul may need a major overhaul at 10,000 to 12,000 engine hours. Maintenance intervals of every 6 months significantly extend that.
What is the difference between a condenser and an evaporator in a TRU?
The condenser releases heat outside the cargo space (usually mounted on the front wall exterior). The evaporator absorbs heat inside the cargo space (mounted on the interior ceiling or wall). Both are part of the refrigeration circuit. If either fails, the unit stops cooling.
Do multi-temperature systems cost significantly more?
Yes. A basic single-zone van conversion starts from approximately AUD $5,000 to $8,000 for supply and install. A dual-zone multi-temperature conversion is typically AUD $12,000 to $18,000 depending on van size, insulation specification, and the units used. The cost difference reflects the additional hardware, wiring, and build time.
