The message center display shows what’s going on in your reefer unit’s
If you’re paid to deliver a load of ice, you won’t see a dime if you arrive with water.
A reefer driver is responsible for his load, and it’s his job to look out for trouble with the reefer and head it off, if possible. Reefers work the same way as your cab air conditioner, but they provide more cooling per gallon of fuel. They are powered by their own engine. Look at one example: in the case of the Carrier Transicold Ultra XTC refrigeration unit, a Kubota direct-injection diesel provides 36 horsepower at 2,200 rpm and glow-plug-assisted starting. We used this unit as a guide to reefer care practices.
We consulted Senior Technician Pat Naylis of Carrier Transicold Pennsylvania East in looking over an Ultra XTC, this one owned by New Century Transportation of Westhampton, N.J. The Ultra XTC offers extended service intervals; the microprocessor controls will even help you keep tabs on developing problems. A pre-trip checkout, partly done by the microprocessor or “micro” that controls the unit, will help guarantee that the unit will run reliably until you deliver your load in perfect condition.
Performing a pre-trip
Naylis recommends performing a pre-trip on your reefer unit each morning before setting out. The unit’s microprocessor is designed to perform a number of checks in an automatic sequence to help you find and fix any problems before you lose a load.
The reefer unit’s engine holds 15 quarts of oil and uses a large filter. This allows oil changes at 2,000 hours, unless you use Mobil Delvac 1 5W-40 oil, in which case 3,000-hour maintenance intervals are the standard. When using Mobil Delvac 1 and the special bypass oil filter, the maintenance interval is 4,000 miles.
The first step when doing the 2,000 or 3,000-hour maintenance is to make sure the engine has been running long enough (at least 30 minutes) to get the oil hot. Then shut down the engine.
To change the oil:
To service the fuel filtration system:
The fuel filter should be changed at 2,000 hours unless an ESI (extended service interval) filter is used. Then the interval is 3,000 hours. This filter can only be fitted to newer models – check the service manual for specifics.
Servicing the air cleaner:
Next, take a look at the air restriction indicator, located below the inlet air hose. The indicator will show red if restriction has been excessive, even if the engine is off when you’re looking at it. If the air cleaner gets clogged, the engine will also smoke quite heavily, Naylis says. But it normally won’t clog between maintenance intervals unless running in a dusty environment. If the indicator shows excessive restriction, the air cleaner should be replaced at more frequent intervals.
Belt condition and tension are critical. Belts will slip if tension is inadequate or they are glazed, Naylis says. This will result in engine overheating and high “head pressure,” the pressure in the condenser. This can result in compressor failure.
Inspect the belts:
Check the oil in the belt drive gearbox:
Return the unit to operation, and allow it to run for at least five minutes to equalize all the pressures. Then check the refrigerant level in the receiver-drier. This device is located just behind the condenser, on the left side of the unit as you face it from the front. It has two sight glasses, with fluid indicated by floating balls. The ball must be floating in the lower sight glass under all circumstances. The ball in the upper glass will be floating only under rare load conditions. If the lower ball is not floating and the unit is giving poor cooling performance, it is probably undercharged with refrigerant because of a leak. Have it serviced by a reefer technician.
Check the oil level in the compressor by looking at the sight glass. The glass is mounted on the visible side of the compressor crankcase. You should see bubbles indicating the oil level about half way up the glass. If the level is low, the refrigerant system probably has a leak and should be serviced.
Because the oil circulates throughout the system and will leak out with any leaking refrigerant, any leak is indicated by a visible oil stain, Naylis says.
Inspect the compressor coupling, located in the well between the engine and compressor. Any visible cracks in the plastic indicate it should be replaced. Check the compressor shaft seal, visible where the shaft goes into the compressor crankcase. Visible dirt indicates the seal is probably leaking. Have the seal checked for a refrigerant leak.
Also, inspect the rubber mounts on the compressor and engine. If rubber has been compressed or is cracked, there may be problems with vibration or even belt slippage and unit overheating. Defective mounts should be replaced by a professional.
Inspect the fan shaft bearing, located behind the drive clutch and pulley on the shaft. Oil leakage means the bearing should be replaced.
Inspect all hoses for brittleness, cracking or chafing and replace as necessary.
Inspect the trailer rubber door seals, and have them replaced if worn or cracked. Poor seal will result in high fuel consumption and an inability to maintain the box temperature.
Doing all these checks and services will help guarantee a minimum of lost loads and a long reefer unit life.
Before starting to work on the unit, you must switch off the Start/Run-Off switch before opening the doors and looking inside the unit. The unit may start at any time unless switched off.
Remember that refrigerant is always under pressure in the entire system. Escaping
refrigerant often results in frostbite. Only those trained in refrigerant system work, familiar with proper service procedures and equipped with special gauges and connectors should ever attempt to open up the service valves or other fittings and charge or discharge the system.
The high pressure lines, compressor surfaces, condenser and related parts will be hot unless the unit has been shut down for some time. Always avoid touching them unless you know the unit has had plenty of time to cool.
Getting Ready for Pickup
Knowing how to properly operate your reefer unit is an important part of the job. First you must find out the required temperature for each load from the shipper, your broker or dispatcher. For example, ice cream is kept at -20 degrees F. Other frozen foods may be kept at about 0 degrees or +10 degrees F. Fresh vegetables are often kept at 35 degrees F.
But switching on the reefer unit when you pick up your load is not enough, Naylis says. Turn the unit on and set the temperature an hour or more before you pick up the load. The box has to be at the set point before you load it.
When the pre-trip has been run, press any key. The temperature set point will then be displayed on the left side of the message center of the controller display. To change the temperature set point, once it is displayed, press the up or down arrows. Once you have brought the set point to the temperature needed for the load, press the = button to set it in the memory and activate it.
The unit normally runs in the start-stop mode. This is the normal mode for frozen food. You’ll see “START STOP MODE SELECTED” in the lower message center and the start-stop light at the top of the controller display will be lit when this mode is selected.
Fresh vegetables and some other cargoes require that the air be circulated constantly to keep humidity from accumulating on the product. In stop-start mode, the engine shuts down as soon as the set temperature is reached, and this stops the fans. However, in continuous mode, the engine will continue to run, and the temperature will be kept at the set point by varying the compressor’s capacity via the cylinder unloaders and suction throttling valve. To set the unit for continuous run, press the START-STOP/CONTINUOUS key until the CONTINUOUS RUN light at the top of the display illuminates, and “CONTINUOUS RUN MODE SELECTED” appears in the lower liquid crystal display.
Thermo King Corp.
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