- 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.
- 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.
- 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.
- 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.
Check the oil in the belt drive gearbox:
- Use an Allen wrench to remove the plug from the right side (as you view the gearbox), and see if fluid drains out.
- 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.
- 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.
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.