The high pressure relief valve vents only enough refrigerant to reduce the A/C system pressure, and then re-
seats itself. The majority of the refrigerant is conserved in the A/C system. If the high pressure relief valve vents
refrigerant, it does not mean the valve is faulty.
The high pressure relief valve is factory-calibrated and cannot be adjusted or repaired, and must not be removed
or otherwise disturbed. The valve is only serviced as a part of the A/C compressor.
COMPRESSOR-A/C
The A/C compressor is driven by the engine through an electric clutch, drive pulley and belt arrangement. The
A/C compressor is lubricated by refrigerant oil that is circulated throughout the refrigerant system with the
refrigerant.
The A/C compressor draws in low-pressure refrigerant vapor from the A/C evaporator through its suction port.
It then compresses the refrigerant into a high-pressure, high-temperature refrigerant vapor, which is then
pumped to the A/C condenser through the compressor discharge port.
The A/C compressor cannot be repaired and must be replaced if inoperative or damaged. The compressor
clutch, pulley and bearing assembly, and clutch field coil are available for service. If an internal failure of the
A/C compressor has occurred, the A/C receiver/drier must also be replaced. See REMOVAL.
DIAGNOSIS AND TESTING
COMPRESSOR-A/C
When investigating an A/C system related noise, you must first know the conditions under which the noise
occurs. These conditions include: weather, vehicle speed, transmission in gear or neutral, engine speed, engine
temperature, and any other special conditions. Noises that develop during A/C operation can often be
misleading. For example: What sounds like a failed front engine bearing or connecting rod, may be caused by
loose bolts, nuts, mounting brackets or a loose compressor clutch assembly.
Drive belts are speed sensitive. At different engine speeds and depending upon drive belt tension, drive belts
can develop noises that are mistaken for an A/C compressor noise. Improper drive belt tension can cause a
misleading noise when the compressor clutch is engaged, which may not occur when the compressor clutch is
disengaged. Check the accessory drive belt condition and tension as described in Cooling before beginning this
procedure.
1. Select a quiet area for testing. Duplicate the complaint conditions as much as possible. Turn the A/C
CAUTION: Be certain to adjust the refrigerant system oil level when replacing an A/C
compressor. See REFRIGERANT OIL LEVEL. Failure to properly adjust the
refrigerant oil level can prevent the A/C system from operating as
designed and can cause serious A/C compressor damage.
CAUTION: The A/C receiver/drier must be replaced if an internal failure of the A/C
compressor has occurred. Failure to replace the A/C receiver/drier can
cause serious damage to the replacement A/C compressor.
2007 Dodge Nitro R/T
2007 HVAC Heating & Air Conditioning - Service Information - Nitro