311B, 312B, 315B, 320B, 322B, 325B and 330B Excavators Air Conditioning and Heating Refrigerant System - Evacuate Caterpillar


Refrigerant System - Evacuate
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311B, 312B, 315B, 320B, 322B, 325B and 330B Excavators Air Conditioning and Heating [RENR1041]
1.1. Flow Chart for the Evacuation Process
2.1. Installing the Manifold Gauge Set (Evacuation)
3.1. Evacuation
4.2. Airtight Check
5.1. Removing the Manifold Gauge Set

------ WARNING! ------

Personal injury can result from contact with refrigerant.

This system is under pressure at all times, even if the engine is not running. Heat should never be applied to a charged system.

Contact with refrigerant can cause frost bite. Keep face and hands away to help prevent injury.

Protective goggles must always be worn when refrigerant lines are opened, even if the gauges indicate the system is empty of refrigerant.

Always use caution when a fitting is removed. Slowly loosen the fitting. If the system is still under pressure, evacuate the system recovering the refrigerant before removing the fitting.

Personal injury or death can result from inhaling refrigerant through a lit cigarette.

Inhaling air conditioner refrigerant gas through a lit cigarette or other smoking method or inhaling fumes released from a flame contacting air conditioner refrigerant gas, can cause bodily harm or death.

Do not smoke when servicing air conditioners or wherever refrigerant gas may be present.

Before any checks of the air conditioning and heating system are made, move the machine to a smooth horizontal surface. Lower all implements to the ground. Make sure the transmission is in neutral or park and that the parking brake is engaged. Keep all other personnel away from the machine or where they can be seen.


If replacement of a component is necessary or repair to a component is necessary, the refrigerant in the system must be recovered. Also, if the system has lost any charge after a long period of time, the refrigerant in the system must be recovered. It is necessary to perform the evacuating procedure to delete the system of all air and moisture. You must run the pump for 90 minutes in order to remove water vapor. Also, you must run the pump for 90 minutes in order to attain the vacuum that is listed in Table 1. A complete charge must never be given to a system without first performing the evacuating procedure. Before you evacuate the system, refer to the following manual.

  • Testing and Adjusting, "Refrigerant Leakage - Test"

  • Testing and Adjusting, "Refrigerant Recovery"

  • Testing and Adjusting, "Refrigerant Compressor Oil - Check"

If the system has been left open for more than 1/2 hour, the system has been exposed to air and to moisture. Therefore, a new receiver-dryer, an in-line dryer or a desiccant accumulator needs to be installed. Moisture will combine with metals in the refrigerant system. This will produce highly corrosive by-products. The by-products are oxides, iron hydroxide and aluminum hydroxide. Moisture can freeze the expansion valve and moisture can freeze the orifice tube. If there is water in the system, the water must be removed by pulling a vacuum and boiling the water for 90 minutes. Refer to Table 1 that is shown below.

Table 1
Boiling Point of Water Under Vacuum 
Temperature of Work Area (°C (°F))  Vacuum That Is Required In Order To Boil Water In An Air Conditioning System (m bar (Hg)) 
38 (100)  948 (28.0) 
32 (90)  965 (28.5) 
27 (80)  975 (28.8) 
21 (70)  988 (29.2) 


NOTICE

All refrigerant must be recovered before the evacuating procedure is started. Never discharge the refrigerant through the vacuum pump.


Flow Chart for the Evacuation Process



Illustration 1g00476489

Installing the Manifold Gauge Set (Evacuation)



Illustration 2g00469391
(1) Low pressure valve
(2) High pressure valve
(3) Low pressure hose
(4) High pressure hose
(5) Service valve (low pressure side)
(6) Charging hose
(7) Vacuum pump
(8) Service valve (high pressure side)
(9) Manifold gauge set

  1. Close low pressure valve (1) and high pressure valve (2) of manifold gauge set (9).

  2. Connect charging hose (6) to vacuum pump (7). This hose was connected to the recovery station when the refrigerant was recovered.

  3. Make sure that the two hoses are properly connected.

Evacuation

The evacuation process is necessary if the following situations occur.

  • Component replacement causes the recovery of refrigerant.

  • The repair of components causes the recovery of refrigerant.

  • Refrigerant charge has been lost for a long period of time.


NOTICE

If the refrigerant system has been open to the outside air (without being plugged) for more than 30 minutes, the receiver-dryer must be replaced. Moisture will enter an open refrigerant system and cause corrosion which will lead to component failure.


This evacuation process will remove all air and moisture from the system.



Illustration 3g00469391
(1) Low pressure valve
(2) High pressure valve
(3) Low pressure hose
(4) High pressure hose
(5) Service valve (low pressure side)
(6) Charging hose
(7) Vacuum pump
(8) Service valve (high pressure side)
(9) Manifold gauge set


NOTICE

All refrigerant must be recovered before the evacuating procedure is started. Never discharge refrigerant through the vacuum pump.


  1. Open high pressure valve (2) and low pressure valve (1). Both valves are located on manifold gauge set (9).

  2. Turn on vacuum pump (7). Evacuate the system for ten minutes.

  3. When manifold gauge set (9) reaches a reading of −0.1 MPa (−14.5 psi) or more, close valves (1) and (2). Make sure that the specified amount of vacuum was reached.

  4. Turn off vacuum pump (7).

Airtight Check

After the evacuation process is complete, leave both valves closed. Keep these valves closed for five minutes. Then, check that the reading on the gauge does not return to zero.

Note: If the reading moves toward zero, a leak is evident. Tighten all connections and evacuate the system again in order to make sure that there is no leak.

Removing the Manifold Gauge Set

To avoid a condition of low charge, properly remove lines of the manifold gauge set. The correct charge can only be obtained if the lines are emptied of all refrigerant.

  1. While the compressor is operating, close the service valve (high pressure side). Disconnect the hose from the system.

  2. On the gauge set, open the high pressure valve and the low pressure valve. The refrigerant in the lines is removed by the compressor through the low pressure hose.

  3. Close the service valve (low pressure side) and disconnect the hose from the system.

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