How to Check step by step Refrigerant Circuit Problems part 6

Refrigerant Circuit Problems

System Condition 10
1. Low pressure gauge reading is too low.

2. High pressure gauge reading is too low.

Note: Ambient temperature is above 21°C (70°F).

3. The temperature of the air flow from the evaporator is partially cool or warm.

4. Moisture (water) or frost is on the expansion valve inlet or orifice tube assembly.

Probable Cause

The problems that are described in Step 1 through Step 4 can be caused by the following faults:

Note: The following faults will cause a restriction of the flow of refrigerant to the evaporator.

* Improper operation of the expansion valve (stuck valve)

* Blockage at the evaporator inlet

* No charge in temperature sensing bulb

Note: The inlet to the expansion valve will be warm during normal operation.

1. If the expansion valve inlet is cool to the touch, perform the following procedure:

* Position the air conditioner temperature control knob to the maximum COOL position and the fan switch to the HIGH position.

* Cool the head of the expansion valve diaphragm chamber and capillary tube with ice or liquid nitrogen. Record the low pressure gauge reading. The low pressure gauge should indicate a vacuum.

* If a vacuum is indicated on the low pressure gauge, place a hand over the expansion valve diaphragm chamber. The hand will warm the expansion valve diaphragm chamber. In order to ensure the correct operation of the expansion valve, cool the head of the expansion valve diaphragm chamber and the capillary tube with ice or liquid nitrogen again. If the operation of expansion valve is correct, refer to Step 2.

* If the low pressure gauge does not indicate proper operation of the expansion valve, remove the refrigerant from the system. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section in Testing and Adjusting.

* Replace the expansion valve. Refer to the Service Manual, SENR5664, "Expansion Valve - (Air Conditioner) Remove and Install" section in Disassembly and Assembly.

Note: The sensing bulb must be installed correctly in order to ensure the correct operation of the expansion valve. Clean the location for the sensing bulb with steel wool or emery paper. Use a 8P-6355 Clip in order to attach the sensing bulb securely to the evaporator coil outlet pipe. Completely cover the assembly with 5P-7070 Strip Insulation .

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

2. If the low pressure gauge indicates the correct operation of the expansion valve, perform the following procedure:

* The sensing bulb must be in the correct position on the evaporator outlet pipe and the sensing bulb must be the correct distance away from the evaporator outlet. The bulb should be upstream from the pressure sensing connection in the evaporator outlet pipe. The insulation must be around the sensing bulb and the clip on the evaporator outlet pipe.

* In order to ensure the correct systems operation, perform a performance check.

3. Replace the in-line dryer or replace the orifice tube.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.


Illustration can look at above

Expansion valve in the closed position (Typical Example)

(1) Capillary tube

(2) Expansion valve diaphragm chamber

(3) Inlet

(4) Outlet

Note: For expansion valve systems, refer to Step 1. For orifice tube systems, refer to Step 3.

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How to Check step by step Refrigerant Circuit Problems part 5

Refrigerant Circuit Problems

System Condition 9

1. Low pressure gauge reading is above normal. For normal operating pressures, refer to Table 1.

2. High pressure gauge reading is normal or low. For normal operating pressures, refer to Table 1.

Note: Ambient temperature is above 21°C (70°F) and the system has a refrigerant charge that is full.

3. The temperature of the air flow from the evaporator is warm.

4. The suction hose and the evaporator is covered with moisture (sweating).

Probable Cause

Flow of refrigerant through the evaporator coil is excessive. The expansion valve could be stuck or held in the OPEN position.

1. Test the expansion valve for the correct operation. Use the following procedure.

* Position the air conditioner temperature control knob in the maximum COOL position and the fan switch in the HIGH position.

* Cool the head of the expansion valve diaphragm chamber and the capillary tube with ice or liquid nitrogen. Record the low pressure gauge reading. The low pressure gauge should indicate a vacuum.

* If the low pressure gauge indicates a vacuum, place a hand over the expansion valve diaphragm chamber. The hand will warm the expansion valve diaphragm chamber. In order to ensure the correct operation of the expansion valve, cool the head of the expansion valve diaphragm chamber and the capillary tube with ice or liquid nitrogen again. If the operation of the expansion is correct, refer to Step 2.

* If the low pressure gauge does not indicate the proper operation of the expansion valve, recover the refrigerant from the system. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section in Testing and Adjusting.

* Replace the expansion valve. Refer to the Service Manual, SENR5664, "Expansion Valve - (Air Conditioner) Remove and Install" section in Disassembly and Assembly.

Note: The sensing bulb must be installed correctly in order to ensure the proper operation of the expansion valve.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

2. If the pressure gauge indicates the correct operation of the expansion valve, perform the following procedure.

* Use a 8P-6355 Clip in order to hold the sensing bulb onto the evaporator outlet pipe. The sensing bulb should be as close to the evaporator as possible. The bulb should be upstream of the pressure sensing connection on the evaporator outlet pipe. The following items must be wound tightly with 5P-7070 Strip Insulation : the clip, the sensing bulb and the outlet pipe. There should be no insulation between the bulb and the outlet pipe.

* In order to ensure that the system operates correctly, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.


Illustration can look at above

Expansion valve in the open position (Typical Example)

(1) Capillary tube

(2) Expansion valve diaphragm chamber

(3) Inlet

(4) Outlet

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How to Check step by step Refrigerant Circuit Problems part 4

Refrigerant Circuit Problems

System Condition 8

1. Low pressure gauge reading is above normal.

2. High pressure gauge reading is below normal.

Note: Ambient temperature is above 21°C (70°F) and the system has a refrigerant charge that is full.

3. The temperature of the air flow from the evaporator is partially cool.

Probable Cause

The compressor has internal leaks. The reed valve has leakage. The compressor piston, rings or cylinders are worn.

* Check the compressor drive belt for the correct tension.

* Perform a leak test. Isolate the problem to the compressor. Refer to the Service Manual, SENR5664, "Refrigerant Leakage - Test" section in Testing and Adjusting.

If an internal leak is found, perform the following procedure.

* Replace the compressor. Refer to the Service Manual, SENR5664, "refrigerant Compressor - remove and Install" section in Disassembly and Assembly.

* Replace the receiver-dryer. Refer to the Service Manual, SENR5664, "Receiver-Dryer - Remove and Install" section in Testing and Adjusting.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

If an external leak such as a hose connection is found, perform the following procedure.

* Recover the refrigerant. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section.

* Repair leaks.

If a large amount of refrigerant is lost, check the compressor for the loss of oil.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

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How to Check step by step Refrigerant Circuit Problems part 3

Refrigerant Circuit Problems

System Condition 6

1. The low pressure gauge reading does not change. The pressure should rise when the compressor is not in operation. For normal operating pressures, refer to Table 1.

2. High pressure gauge reading is at the high end of the normal range.

Note: Ambient temperature is above 21°C (70°F).

3. The temperature of the air flow from the evaporator is partially cool.

Probable Cause

The system has air or moisture in the system. The system does not have a full charge of refrigerant.

* Perform a leak test and carefully test around the compressor seal. Refer to the Service Manual, SENR5664, "Refrigerant Leakage - Test" section in Testing and Adjusting.

* Recover the refrigerant from the system. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section in Testing and Adjusting.

* Repair leaks.

* Check the compressor for loss of oil.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

System Condition 7

1. Low pressure gauge reading is above normal. For normal operating pressures, refer to Table 1.

2. High pressure gauge reading is above normal. For normal operating pressures, refer to Table 1.

Note: Ambient temperature is above 21°C (70°F).

3. High pressure (liquid line) is very hot.

4. The compressor may become noisy and the drive belt may slip.

Note: The compressor is not operating under ambient temperatures that are extreme. The compressor is not operating under high humidity that is extreme.

Probable Cause

The system is overcharged.

* Recover the remaining refrigerant. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* Perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

Note: Perform the following procedure if the system has not been serviced for a extended period of time. Perform the following procedure if the pressures of the system are not within the correct specifications.

* Recover the refrigerant. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting. If service work has not been performed for a extended period of time, replace the receiver-dryer or the in-line dryer.

* Charge the system with the correct amount of refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

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