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Proposed Maintenance Advisory —
Heavy-duty in-cab air conditioning

Inspect the Evaporator Coil to see that it is free of dust, leaves, and other foreign material which may have been drawn through the air filter. Debris on the evaporator coil or fan blades will impair the cooling efficiency and reduce the air flow. Remove the debris by using a vacuum hose or air hose. Use care to prevent possible damage to near-by components such as blower wheels, wiring and capillary tubes. ASSURE THAT THE CONDENSATE DRAIN HOSE IS CLEAR OF ALL DEBRIS.

The Condenser Coil should be periodically cleaned in the same way to remove insects, leaves, straw, and other debris. A partially blocked condenser will cause excessive head pressure and reduce the cooling performance of the system and shorten the compressor and clutch life.

Inspect belts for proper tension. Loose belts cause slippage which results in intermittent cooling and BELT DAMAGE. Belts under excessive tension will place damaging stress on the clutch, compressor bearings and crankshaft. Too much tension will also reduce flex life of the belt. Retighten loose compressor belts to 100 lbs.

Inspect alignment of the clutch to the drive pulley. If the compressor has shifted out of alignment, belt wear and clutch bearing failure will result. Drive belt misalignment must not exceed .01 inch per inch. (1/8” per foot)

If the system is a combination heater and air conditioner, check to assure WATER VALVE SHUTS OFF WATER FLOW TO THE HEATER CORE.

Check the sight glass to determine the level of Freon. Run the engine at 1200-1500 RPMs and return to idle. If bubbles appear continuously, there is a possibility of a refrigerant leak. IF THE AMBIENT TEMPERATURE IS BELOW 70 DEGREES F. THE SIGHT GLASS MAY SHOW BUBBLES EVEN WITH THE PROPER REFRIGERANT LEVEL.

Inspect the hoses for abrasion or wear, particularly at bends, clamps, or in areas that may rub against parts of the machine. Check compressor discharge hose for bake out hardness close to compressor.

Inspect the drain hose leading from the evaporator. It should not be forced into the unit as to cause looping which restricts the natural flow of moisture. Restricted drainage due to kinking or accumulation of dirt and debris will over flow the condenser drainage system and cause leaking of the unit.

Nuts and bolts on the compressor mounting bracket and clutch should be tightened securely before inspecting and adjusting the belt tension and pulley alignment. Recheck the pulley for alignment with unit operating.