Bronco L6-300 4.9L VIN Y 1-bbl (1983)
Refrigerant Pressure Sensor / Switch: All Technical Service Bulletins
A/C - Pressure Cycling Switch Diagnostic Procedure
AIR CONDITIONING-CLUTCH PRESSURE CYCLING SWITCH DIAGNOSTIC PROCEDURE
Article No. 89-14-10
FORD: 1980-89 CROWN VICTORIA 1981-89 ESCORT 1982-88 EXP 1982-89 MUSTANG, THUNDERBIRD 1983-86 LTD 1984-89 TEMPO
1986-89 TAURUS
LINCOLN-MERCURY:
1980-89 GRAND MARQUIS, MARK VI, MARK VII, TOWN CAR
1981-87 LYNX 1982-86 CAPRI 1982-89 CONTINENTAL, COUGAR 1983-86 MARQUIS 1984-89 TOPAZ 1986-89
SABLE
LIGHT TRUCK: 1980-89 BRONCO, F SERIES 1983-89 RANGER 1984-89 BRONCO II 1986-89 AEROSTAR 1988-89 ECONOLINE
ISSUE:
Poor air conditioning cooling caused by low or no refrigerant charge often results in unnecessary replacement of the clutch cycling pressure
switch. The switch is designed to work on system pressure. It closes at about 46 psi and opens at about 24.5 psi. It has a normal cycle (on and
off) rate of 2 to 5 cycles per minute.
ACTION:
If an inoperative or fast cycling pressure switch is found, use the following diagnostic charts before replacing the pressure switch.
DIAGNOSTIC PROCEDURE:
1.
Connect a manifold gauge set to the service ports and check the system pressures. They should be above the closing pressure of the switch (46
psi).
2.
If the A/C system pressures are above 46 psi and the clutch will not engage, proceed as follows:
^
Check the pressure switch harness connector and harness wires for a continuous open condition.
^
Check for an intermittent open or a poor connection between the connector and the pressure switch terminals.
a.
If the harness connector and wires are OK, by-pass the pressure switch by jumping the two terminals of the connector. If the clutch still does not
engage, THE PRESSURE SWITCH IS NOT DEFECTIVE. Refer to the respective EVTM for the clutch circuit schematic and circuit diagnosis.
Repair as necessary.
3.
Check the ambient temperature. If the ambient temperature is below 48~ F (9~ C), the system pressure will not be high enough to close the
pressure switch (46 psi).
4.
If the system does not contain refrigerant, the pressure will not be high enough to close the switch for compressor operation. Leak test, repair,
evacuate and charge the system.
