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


Refrigerant System - Charge
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1.1. Flow Chart for Charging Refrigerant
2.1. Charging the System from the High Pressure Side
3.1. Charging the System from the Low Pressure Side
4.1. Replacement of Refrigerant Tank
5.1. Criteria for the Amount of Refrigerant Needed

------ 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.

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

Personal injury or death can result when charging an air conditioning system with a liquid.

The compressor will pump the refrigerant back into the charging cylinder with the possibility of rupturing (exploding) the cylinder.

Do not operate the engine when charging with a liquid.

Never charge liquid or gas through the discharge (high side of the system) with the engine running.

Keep all other personnel either away from the machine or where they can be seen when working on the air conditioning system.

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Charge the refrigerant circuit only after the evacuation process has been completed. Use a refrigerant tank and a scale in order to charge the system.

Stop the engine. Charge refrigerant from the high-pressure side.

If the system has not been run recently, a 208-1352 Heater is necessary in order to warm the refrigerant tank. A warm refrigerant tank is critical in order to accomplish a full charge of refrigerant. When you charge the system, the system must be maintained in the temperature range 21 °C (70 °F) to 29 °C (85 °F).

Flow Chart for Charging Refrigerant




Illustration 1g01134632

Charging the System from the High Pressure Side




Illustration 2g01134635

(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

(8) Service valve (high-pressure side)

(9) Manifold gauge set

(10) Valve on top of refrigerant tank

(11) Refrigerant tank

(18) Scale

  1. After the evacuation process is completed, connect charging hose (6) to refrigerant tank (11). Hose (6) is the hose that was connected to the vacuum pump.

  1. Open valve (10) that is located on top of refrigerant tank (11). Make sure that pressure valves (1) and (2) are closed. These two valves are located on manifold gauge set (9) .

  1. Purge any air that may remain in the lines by loosening charging hose (6) at the manifold gauge set. Tighten charging hose (6) after 2 to 3 seconds.

    Note: Use a heater blanket in order to warm the refrigerant tank if the tank is not full. Use a heater blanket to warm the tank if the ambient temperature is below 21 °C (70 °F) .

  1. Place refrigerant tank (11) on scale (18). Record the weight of the tank.

  1. Open high-pressure valve (2) of manifold gauge set (9) and charge the system. Check the weight of the tank often. The weight will decrease as the refrigerant leaves the tank and the refrigerant enters the system. Refer to Specifications, "System Capacities for Refrigerant" for the proper amount of refrigerant. The necessary amount of refrigerant is the system capacity by weight. Charge the system with the necessary refrigerant. Close the high-pressure valve (2) of the manifold gauge set (9). You must also close valve (10) that is located on top of refrigerant tank (11) .

  1. Restart the engine and run the engine at the rated RPM until the pressure stabilizes.

  1. To ensure correct system operation, disconnect charging hose (6) and do a performance check. Refer to Service Manual, "Performance Checks for the Air Conditioning System" for the proper procedure.

Charging the System from the Low Pressure Side

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

Personal injury or death can result when charging an air conditioning system with a liquid.

The compressor will pump the refrigerant back into the charging cylinder with the possibility of rupturing (exploding) the cylinder.

Do not operate the engine when charging with a liquid.

Never charge liquid or gas through the discharge (high side of the system) with the engine running.

Keep all other personnel either away from the machine or where they can be seen when working on the air conditioning system.

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Note: If the refrigerant circuit contains no refrigerant, always evacuate the system before you charge the system. Also, be sure to charge the system by weight.




Illustration 3g00470339

(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

(8) Service valve (high-pressure side)

(9) Manifold gauge set

(10) Valve on top of refrigerant tank

(11) Refrigerant tank

(12) Butterfly valve

(18) Scale

This procedure is NOT the preferred procedure, but this procedure may be required under the following conditions:

  • The tank pressure is too low.

  • The ambient temperature is too low and a heater blanket is not available to warm the system.

Use a scale in order to measure the amount of refrigerant that is charged. Do not use pressure in order to measure the amount of refrigerant that is charged.

Refer to Illustration 3 for the following steps.

  1. Connect the manifold gauge set to the discharge and service ports on the compressor. Refer to Testing and Adjusting, "Manifold Gauge Set (Refrigerant) - Install" for the proper procedure.

  1. Make sure that high-pressure valve (2) and low-pressure valve (1) of manifold gauge set (9) are closed.

  1. Purge any air that may remain in the lines by loosening charging hose (6) at the manifold gauge set. Tighten charging hose (6) after 2 to 3 seconds.

  1. Set the machine to the following conditions:

    • Start the engine and open the door.

    • Turn on/off switch ON.

    • Set the temperature select switch to MAX COOL.

    • Set the fan speed switch to HI.

    • Increase engine speed to 1500 to 1600 rpm.

  1. Open low-pressure valve (1) of manifold gauge set (9). Also open valve (10) that is located on top of refrigerant tank (11). Low-pressure hose (3) connects to service valve (5) on the suction side of the compressor. Note the readings on the manifold gauge set. The gauge readings should not exceed the normal operating ranges during this procedure.

  1. Slowly add refrigerant until the inlet of the receiver-dryer is cool and the outlet of the receiver-dryer is cool. The temperature of the discharged air should drop during this procedure. When the air temperature drops adequately, close low-pressure valve (1) and allow the system to stabilize for 5 minutes. Proceed to step 7.

    Note: If the low-pressure valve (1) is opened completely, the low-pressure gauge reading will appear excessively high until the system becomes fully charged.

    Note: If the suction and discharge pressures become too high, indications of an overcharge are present. Proceed to step 9 if an overcharge occurs.

  1. The system is charged. Close low-pressure valve (1) on the manifold gauge set and close valve (10) on refrigerant tank (11) .

  1. Stop the engine and remove the manifold gauge set. This procedure is complete.

  1. Close valve (10) on the refrigerant tank and shut down the engine.

  1. Recover the refrigerant charge and evacuate the system.

  1. Charge the system. Refer to"Charging the System from the High Pressure Side".

Note: Avoid system overcharge. System overcharge causes a sudden rise of high pressure and deterioration of the refrigerant. Overcharging can cause the entire system to operate poorly. Therefore, charge the proper amount of refrigerant.

Note: When the air conditioner is lacking refrigerant, damage to the compressor can occur. Overcharging the refrigerant puts abnormally high pressure into the system. An overcharge of the refrigerant causes deterioration of the refrigerant. An overcharge of the refrigerant can also cause rapid failure of the compressor.

The air conditioner should be kept ready for operation year-round. Operate the air conditioner for a few minutes during the week in order to rotate the compressor. Operating the air conditioner prevents the leakage of refrigerant. The leakage is caused by a dry seal on the compressor.

Replacement of Refrigerant Tank

If refrigerant tank (11) becomes empty and the system is not fully charged, replace the tank.




Illustration 4g00470339

(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

(8) Service valve (high-pressure side)

(9) Manifold gauge set

(10) Valve on top of refrigerant tank

(11) Refrigerant tank

(12) Butterfly valve

(18) Scale




Illustration 5g00470470

(10) Valve

(11) Refrigerant tank

(13) Handle

(14) Connection for charging hose

(15) Round plate

(16) Needle

(17) Packing

Refer to Illustration 4 and refer to Illustration 5.

  1. Make sure that high-pressure valve (2) and low-pressure valve (1) of the manifold gauge set (9) are closed.

  1. Pull up needle (16) and round plate (15) from refrigerant tank (11) .

  1. Install a new refrigerant tank to valve (10) of the old refrigerant tank.

  1. Follow the steps below in order to purge any air that is remaining in charging hose (6) .

    • Tighten handle (13) of valve (10) until needle (16) punches a new hole in the fresh tank.

    • Open valve (10) .

    • Push in butterfly valve (12) of manifold gauge set (9) until you hear the release of refrigerant.

  1. Continue to charge the system.

Criteria for the Amount of Refrigerant Needed

Do not determine the amount of R134a refrigerant in the system from the sight glass. This method is not preferred.

Evacuating the system and recharging the system by weight is always the best method.

The following conditions must be met in order to utilize the sight glass.

  • The ambient temperature must be in the range from 21 °C (70 °F) to 29 °C (85 °F).

  • Start the engine and open the door.

  • Turn on/off switch ON.

  • Set the temperature select switch to MAX COOL.

  • Set the fan speed switch to HI.

  • Set the air inlet select switch to Recirculation.

  • Increase engine speed to 1500 ± 50 rpm.




Illustration 6g01134793

(18) Sight glass

  • In sight glass (A), no bubbles are visible. No bubbles indicates that there is too much refrigerant in the system.

  • Sight glass (B) contains only a few small bubbles. Small bubbles indicate that there is a satisfactory amount of refrigerant.

  • In sight glass (C), many bubbles are present. Many bubbles indicate that there is a lack of refrigerant.

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