BOWL 9B7922 - Caterpillar

Introduction to Air Conditioning Service Tools
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When you are servicing an air conditioning system, many special tools are needed in addition to the basic mechanic's tool box. Several special tools are covered in the following materials.Electronic Leak Detector
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The electronic leak detector is considered to be the safest and most accurate means of finding a leak in the system. Many electronic detectors can detect small leaks that are equivalent to 1/2 oz. per year. When the leak is found, the detector will beep, activate a light, or the detector will beep and activate a light.To obtain accurate results, leak detection must be performed with the system under pressure. A 50% refrigerant charge in the system is enough to locate most leaks. Very small leaks may require that the system pressure be increased above normal before the leaks can be located.Refrigerant Tanks
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The standard tank (1) in which refrigerant is sold should never be used to reclaim refrigerant. Refrigerant tanks (2) that are used on recovery/recycling equipment, must be approved by the Department of Transportation (DOT). DOT approval is indicated by "DOT 4BW" or "DOT 4BA" that is stamped into the tank.Safety codes recommend that closed tanks not be filled with liquid over 80% of the tank volume. The remaining 20% of the tank volume is left for liquid expansion.This is called head pressure room.Recover, Evacuate, and Charge Unit
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The refrigerant recovery unit should be used to recover refrigerant from the air conditioning system when you make repairs. The refrigerant can then be recycled and reused in the system after the repairs are completed.An automatic air conditioning recover, evacuate, and charge unit may be used to perform a one step recovery, evacuating, and charging operation. The evacuation time and the amount of refrigerant charge are both programmed into the unit. After the refrigerant has been recovered, the unit will evacuate and charge the air conditioning system automatically.A large variety of units are available. Some units (Illustration 4) are used to recover, recycle, evacuate, and charge refrigerant. Other units may only recover the refrigerant. The refrigerant is then transferred to a recycling unit in order to be recycled.Vacuum Pump
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The vacuum pump completely removes all air and moisture from the air conditioning system. This is done by lowering the pressure within the system to a point where moisture turns to a vapor. The vapor is then pumped out of the system with the air.To remove all moisture from the system, the vacuum pump should operate with the low pressure gauge at 981 mbar (29 in. Hg) for a minimum of 30 minutes.Note: All refrigerant should be recovered from the system before you connect the vacuum pump.Refrigerant Charging Scales
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The two types of refrigerant charging scales are the manual operated type (1) and the automatic type (2). Each type allows the specified amount of refrigerant to be added to the system regardless of the ambient temperature.Currently, the charging scale is the recommended method when you charge the air conditioning system on