Refrigerant

HEATING / AIR CONDITIONING: REFRIGERANT: ON-VEHICLE INSPECTION

1. INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET

HINT
The following examples show the readings of a manifold gauge set and the corresponding air conditioning system problems.

(a) Read the manifold gauge pressure when the following conditions are met:

* Doors are fully open.

* The power switch is on (READY).

* The A/C switch is on.

* The temperature is set to max cool.

* The blower speed is set to high.

* Temperature at the air inlet with recirculate selected is 30 to 35°C (86 to 95°F).

(1) Normally functioning air conditioning system.





Gauge Reading





(2) Abnormally functioning air conditioning system.

1 During operation, pressure on low pressure side cycles between normal and vacuum









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HINT
For the example above, moisture is present in the air conditioning system.

2 Pressure is low on both low and high pressure sides









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HINT
For the example above, there is insufficient refrigerant.

3 Pressure is low on both low and high pressure sides









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HINT
For the example above, there is poor circulation of refrigerant

4 Vacuum is indicated on low pressure side and very low pressure is indicated on high pressure side









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HINT
For the example above, the refrigerant does not circulate.

5 Pressure is too high on both low and high pressure sides









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HINT
For the example above, the air conditioning system is overcharged or cooling effectiveness of condenser is insufficient.

6 Pressure is too high on both low and high pressure sides









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NOTICE:
These gauge indications occur when the air conditioning system has been left open and then recharged without evacuating the system.

HINT
For the example above, air is present in the air conditioning system.

7 Pressure is too high on both low and high pressure sides









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HINT
For the above example, there is an expansion valve malfunction.

8 Pressure is too high on both low and high pressure sides or pressure is too low on high pressure side









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HINT
For the above example, there is insufficient compressor compression.

(3) Gauge readings (Reference)





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