COVER AS 3407387 - Caterpillar

Check for frost at the dryer outlet.Note: Moisture on the drier outlet tube after the orifice is normal and this moisture does not indicate a failure with the dryer. Frost on the drier outlet tube after the orifice is an indicator of a low refrigerant charge.
If frost is indicated at the dryer outlet or if pressures are low, proceed to Step 7. Otherwise, proceed to Step 14.
Recover the refrigerant charge from the machine.Refer to Service Manual, SENR5664, "Refrigerant Recovery".
Record the amount of refrigerant and oil that is recovered from the Air Conditioner system.These values will be needed in order to calculate the amount of oil that is needed. Refer to Service Manual, SENR5664, "Refrigerant Compressor Oil - Check" in the Testing and Adjusting Section.
If the charge was low, check the system for leaks.
Use an Ultraviolet light and use an electronic leak detector.Ensure that the following items are checked:
Quick disconnects which are on the dryer
Tighten the drier swivel nut to 27 4 N m (20 3 lb ft).
All connections with O rings in the circuit
Hoses for rubbing, bulging, wet spots (oil leaks)Note: In order to help reveal leaks, simulate the vibrations which are made by the machine by moving the connections.
Recharge the refrigerant.Refer to Service Manual, SENR5664, "Refrigerant System - Charge" in the Testing and Adjusting Section.
Retest the system with the engine at 1400 rpm and check for frost at the dryer outlet.
Ensure that the pressures are normal for the current ambient temperature.Refer to Table 1 for the pressures which are normal for the current ambient air temperature.
If a component is leaking, bill the claim against the leaking component and provide details in the description.
End of TestFor the correct replacement procedures, refer to Service Manual, SENR5664, "In-Line Refrigerant Dryer - Remove and Install".Indications from the Compressor Pressures
Refer to Table 2 in order to diagnose the pressure indications.
Table 2
   
High Discharge    
High Suction    
Low Discharge    
Low Suction    
Pressures Sporadically Fluctuating    
Too much refrigerant charge    
X    
X                
too much oil    
X                    
Restriction on air side of condenser    
X                    
Plugged orifice tube    
X                    
Restriction in high side of refrigerant circuit    
X                    
Condenser fans are not operating correctly.    
X                    
System load high (high ambient, high humidity, doors open)    
X                    
Air in the refrigerant circuit    
X                    
Missing orifice tube        
X                
Thermostat faulty or improperly adjusted        
X                
Low refrigerant charge            
X    
X