KNOB AS 1500597 - Caterpillar

Caterpillar Products: with Cabs
AllService Magazine SEBD1815, 17 April 1978, "Preparation of Air Conditioner Units for Seasonal Operation". The procedure for preparing air conditioners for seasonal use has been updated in order to include refrigerant R134a.Inspection and maintenance of air conditioner units before they are used regularly can improve the performance of the units. Also, troubleshooting the air conditioner units now will decrease future downtime caused by system failures. During these early checks, many servicemen do not check, test, or adjust several important areas. The areas that follow can cause problems, and as a result can cause much downtime.
Clean or install new fresh air and recirculating air filters.
Check and clean condenser and evaporator coils as necessary. Do not steam clean. Straighten any damaged fins that are on the evaporator coils and on the condenser coils with the 8T-9275 Radiator Tool Gp (Fin Straightener).
Check condensate drain lines for free flow of condensate, and check for proper location of the drain valve. If necessary, flush the lines with water and relocate the valve. The valve should be located between flush and 76 mm (3 inch) from the end of the drain line.
Check and clean clutch wire connection for the compressor. To check clutch operation on systems with adjustable thermostats, turn the thermostat on and off. On some other systems, turn the A/C switch on and off. Systems that have the compressor protection system will need up to 30 seconds before the clutch engages.For systems that are not used for extended periods, run the compressor monthly for a minimum of 30 seconds. This will keep the shaft seal from drying out, leaking oil, and leaking refrigerant.
Check the condition and tension of the compressor drive belt. For compressors that are driven by a V-belt, use 144-0235 Belt Tension Gauge per Service Manual, SENR5664, "Air Conditioning and Heating R-134a All Caterpillar Machines".
Check all hoses and connections for refrigerant leaks. Leaks can be identified by signs of oil and dust accumulation or dye accumulation. Check hoses for worn or scuffed (damaged) areas. Replace hoses that are damaged. As required, add protection to the hoses or relocate the hoses.
Do the performance check as shown in the following manuals: for refrigerant R12 systems, see Service Manual, SENR3334, "Air Conditioning and Heating with R12 Refrigerant" and for R134a refrigerant systems, see Service Manual, SENR5664, "Air Conditioning and Heating R134a All Caterpillar Machines". The ambient air temperature needs to be 10 °C (50 °F) or above for R12 systems and 21 °C (70 °F) or above for R134a systems. If the performance check shows a low charge or the system has been used for two or more years (R12) or one year (R134a) then perform the following steps:
Do a leak check.
Recover the system charge.Note: Do NOT vent refrigerant to the atmosphere.
Change the receiver-dryer, the dryer, the in-line dryer, or the accumulator with desiccant.
Evacuate for 30 minutes.
Recharge the system according to the specifications.
Do another leak check
Do the performance check again after the system has been charged.
Remember that charging an R134a