Low Pressure Sensor/ Switch Replacement for 1994 90CS Quattro V6-28L (AAH)
Low Pressure Sensor / Switch: Service and Repair
Location: In passenger compartment on the passenger side between heater housing and bulkhead.
Function:
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Switches A/C clutch -N25- off if system suction pressure is too low (low refrigerant charge). This switch protects the compressor if the refrigerant
system is empty.
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Switch opens (compressor off): 1.45 - 1.6 bar (21 - 23 psi)
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Switch closes (compressor on): 2.9 - 3.4 bar (42 - 49 psi)
Removing And Installing:
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Remove passenger side lower instrument panel cover.
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Remove Engine Control Module (ECM) -A- in direction of arrow. See Powertrain Management.
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Disconnect electrical connector from low pressure switch -F73-.
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Using 17 mm open end wrench approx. 80 mm (3 in.) long, remove low pressure switch.
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Refrigerant system remains closed (Schrader valve under switch).
NOTE: Image shows low pressure switch -F73- with the heater housing removed.
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Install new 0-ring -A- (8.9 mm x 1.8 mm), lubricate with refrigerant (PAG) oil and make sure it is properly seated in groove.
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Install switch.
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Tightening torque: 5 Nm (44 in. lb)
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Reinstall Engine Control Module (ECM) and passenger side lower instrument panel cover