Chill Factor

| August 01, 2005

The message center display shows what’s going on in your reefer unit’s
microprocessor.

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.

  1. Turn the unit off, allow it to sit for three minutes or so, and check the engine oil level.

  2. Glance at the coolant overflow tank [in this unit’s case it is located in the top corner of the unit on the driver’s side]. Never open the radiator cap unless the engine has cooled thoroughly.
  3. Glance at the fuel filter. If there is water or dirt obvious in the bottom of the bowl, open the drain cock and drain enough fuel into a safe container to remove the accumulated dirt or moisture. If you need to drain a lot of fuel to clean up the bowl, you can reprime the system by pumping the priming pump next to the engine’s injection pump. Just open the red valve, unscrew the top of the priming pump, and pump the plunger up and down to operate.
  4. Check the belts to make sure they are not cracked or frayed. This should not be a major concern as long as you inspect and adjust them at maintenance intervals.
  5. Run a pre-trip check of the system’s component via the micro. To do this, first turn the Start/Run-Off switch on. Then press the Select key until the message center display indicates “PRESS THE = KEY TO START PRETRIP.” Once this message shows up, press the = key below the up and down arrows.
  6. You’ll now see TEST #1 in the message bar. Verify that the complete display is turned on, all the lights in the light bar come on, and that the buzzer buzzes.
  7. Once the pre-trip is completed, the unit will continue running at the previously set temperature and in the previously selected running mode. “PRETRIP PASS,” “PRETRIP FAIL AND COMPLETE” or “PRETRIP FAIL IN TEST” will be shown if the pre-trip cycle was aborted by an alarm before completion. Any problems that were found will be spelled out. If an alarm is shown that allows the unit to continue operation (the pre-trip was completed), get the problem repaired as soon as possible. If the unit fails any critical tests, it becomes inoperable until repaired to prevent damage to its internal components.

Routine Maintenance
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:

  1. Place a 20-quart pan below the drain plug and remove the plug. While the oil drains, make sure the pan can also collect oil from the oil filter, and then unscrew the filter with a strap wrench and remove it.

  2. Wipe the filter base with a clean rag. To replace the filter, coat the rubber gasket with clean engine oil. Then install and tighten it the number of turns past the point where the gasket contacts the base that are specified on the side.
  3. Allow a few minutes for all the oil to drain, wipe the plug and seating surfaces on the oil pan, and then reinstall and tighten the plug.
  4. Refill the engine with oil and start the engine and run it until oil pressure is established before shutting down for the remainder of the work.

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.

  1. Place a pan under the filter. Loosen the drain plug, and use a strap wrench to loosen the filter slightly at the top. Drain the filter bowl and filter. A drain hose can be connected to the drain plug.

  2. Once the filter has drained, unscrew it from the mount at the top and remove the bowl from the bottom. Wipe the bowl out with a clean rag, coat the gaskets at top and bottom with clean engine oil, and screw the bowl onto the lower end of the new filter and tighten it. It’s easy to tell which end the bowl is screwed onto – the filter must end up so the printing is right-side up.
  3. Fill the filter and bowl to the top with clean diesel fuel.
  4. Install the filter onto the mount and tighten with a strap wrench as recommended on the side.
  5. Open the red bleed valve. Then unscrew the priming pump plunger and operate the pump by pulling the plunger up and down slowly. When you feel resistance, the system should be getting full. To ensure proper prime, start the engine and run it while pumping until it runs steadily. Then shut it down and close the bleed valve.
  6. Clean the inlet strainer in the fuel pump by first unscrewing the mounting bolt that attaches the inlet fuel line. Remove the upper copper ring seal, pull the banjo fitting off the bolt and then remove the bolt, keeping the lower copper ring on the bolt. Unscrew and remove the strainer. Replace the seals if the rubber centers are worn.
  7. Blow the strainer out with compressed air and clean it in solvent; then dry and replace in reverse order.

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.

  1. Remove the left side door for access. Pull down on the upper hinge pin to disengage it and then remove the door.

  2. Unfasten the clips and pull the cover off the air cleaner assembly. Then remove the air filter.
  3. Press the new filter into position so that its rubber seal is forced over a fitting until it seats. Then reinstall the cover with the water drain downward and “TOP” marking at the top, and fasten the clips.

Belt checks
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:

  1. Check for cracks between the ribs and for glazing. The belts must be replaced if showing either trouble sign. Although belt tensioning is simple, replacement is complicated and should be left to a professional mechanic.

  2. Check belt tension. If possible, use a belt tension gauge. If none is available, check to see whether or not the belts offer solid resistance when you press them inward with your thumb. Tension should be adjusted if the belt moves with little pressure.
  3. To adjust tension, the idler pulley must be rotated. On the lower belt, first loosen the large hinge bolt at the bottom of the pulley and the upper bolt where it slides. Use a prybar to pull the pulley slightly toward you to tension the belt, and then tighten the bolts. On the upper belt, only a single bolt has to be loosened and retightened.
  4. A small belt drives the generator on the outboard end of the engine. It should be tensioned only by hand by rotating the generator, after loosening the hinge bolt at the top and the adjusting bolt at bottom. The adjusting bolt should be torqued to 16 pounds-feet and the hinge bolt to 80 pounds-feet.

Oil checks
Check the oil in the belt drive gearbox:

  1. Use an Allen wrench to remove the plug from the right side (as you view the gearbox), and see if fluid drains out.

  2. Bring the fluid level up to the bottom of the plug, but don’t overfill it. Too much lube means churning and overheating. Use the approved fluid.
  3. Reinstall the plug and tighten till just snug.

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.


Safety First
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.


For further information, please contact the following:

Carrier Transicold
www.transicold.carrier.com
(800) 227-7437

Thermo King Corp.
www.thermoking.com
(952) 887-2200

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