Engine Cooling Fan — Ford Mustang III рестайлинг (1986-1993)

DESCRIPTION

The system is designed to have engine cooling fan operation, whenever the A/C compressor is operating or whenever the engine coolant temperature reaches 221°F (105°C) with the ignition switch in the "ON" position. A cooling fan controller is used to energize cooling fan. The cooling fan controller is located under instrument panel, between steering column and left side cowl panel.

OPERATION (MUSTANG)

The cooling fan controller consists of 2 relays mounted on a printed circuit board. One relay powers the fan motor, the other relay powers A/C compressor clutch coil.

When engine coolant temperature reaches 221°F (105°C), the cooling fan temperature switch (located in heater hose tube) will close, completing ground circuit to fan relay coil in cooling fan controller. When the relay is energized, contacts close to complete circuit for engine cooling fan motor operation. The fan will continue to operate until engine coolant temperature drops to approximately 201°F (94°C).

During A/C operation, A/C clutch cycling pressure switch controls evaporator temperature by controlling compressor operation. The pressure switch will cause the fan relay to operate first (within 2-4 seconds of start-up), then A/C relay will operate if voltage is available at fan motor terminal. The A/C compressor will cycle together with the A/C pressure switch. The cooling fan motor will remain on for A/C pressure switch open intervals less than 2 minutes.

The fan motor will de-energize if A/C pressure remains open for more than 2 minutes or if ignition switch is turned to the "OFF" position. Under wide open throttle conditions, the A/C compressor will de-energize, but cooling fan motor will continue operating. Turning A/C or defrost demand switch to "OFF" position will not disengage cooling fan motor for 2-3 minutes unless ignition switch is turned to "OFF" position.

Scheme 3

Scheme 3: COOLING FAN INOPERATIVE

Disconnect fan motor lead and install a jumper wire between negative lead and ground. Install jumper lead between positive lead and battery voltage. If fan motor does not run, replace fan motor. If fan motor runs, reconnect fan motor lead and go to next step.
Disconnect coolant temperature switch connector and install a jumper wire between connector and ground on circuit No. 45. Turn ignition switch on. If fan motor runs, check coolant temperature switch ground circuit No. 45. (Scheme 3) If okay, replace coolant temperature switch. If fan motor does not run, go to next step.
With ignition off, remove jumper wire. Check continuity of circuit No. 45 from cooling fan controller (terminal No. 1) to coolant temperature switch. If no continuity is present, fix open in circuit No. 45. If continuity is present, install jumper wire between coolant temperature switch and ground and go to next step.
Install a jumper wire between circuit No. 687 of cooling fan controller connector (terminal No. 8) and battery voltage. If motor runs, check ignition feed circuit No. 687 for an open. (Scheme 4) If motor does not run, remove jumper wire and go to next step.
Disconnect cooling fan controller connector. Jumper circuit No. 228 (terminal No. 5) to battery voltage. If motor runs, remove jumper wire and go to next step. If not, check for open in circuit No. 228.
Install a jumper wire between circuits No. 68 (terminal No. 2) and No. 228 (terminal No. 5) at the cooling fan controller connector. If motor does not run, check circuit No. 68 for an open. If fan motor does run, replace cooling fan controller and remove jumper from coolant temperature switch.

FAN WORKS BUT DOES NOT OPERATE IN A/C MODE

Turn A/C switch to "ON" position. Wait for 5 seconds. If fan motor does not operate, go to next step. If fan motor goes off and on repeatedly, go to step 7).
Check 20 amp fuse in fuse panel. If fuse is blown, replace it. If not, disconnect A/C clutch cycle pressure switch connector and install a jumper wire between terminals of connector. If fan motor runs, go to next step. If not, go to step 6).
Check A/C system for loss of refrigerant charge. If refrigerant level is low, add refrigerant. If refrigerant pressure is above 50 psi (3.5 cm/kg 2 ), go to next step.
Check for continuity between terminals of A/C clutch cycling pressure switch with connector removed. If continuity is present, go to next step. If not, replace A/C clutch cycling pressure switch.
Check for voltage of circuit No. 348 at A/C clutch cycling pressure switch connector. (Scheme 3) If voltage is present, go to step 7). If no voltage is present, go to next step.
Check for voltage at circuits No. 296 and 348 at function selector switch in instrument panel. If voltage is present on circuit No. 296, but not on circuit No. 348, A/C control assembly is defective. If no voltage is present at circuit No. 296, check for short on circuits No. 296 and 297 to the ignition switch.
Check for voltage on circuit No. 883 (pin No. 6) of cooling fan controller. (Scheme 3) If voltage is present, go to next step. If voltage is not present, repair open in circuit No. 883 to the controller.
With fan controller connected, ground circuit No. 57 (pin No. 4) of the controller. If fan runs, repair ground circuit No. 57. If not, replace fan controller.

TROUBLE SHOOTING ABBREVIATIONS

A/C: Air Conditioning

ACCS: A/C Cycling Switch

DVOM: Digital Volt/Ohm Meter (see VOM)

ECT: Engine Coolant Temperature sensor

EDF: Electric Drive Fan relay assembly

EEC: Electronic Engine Control

FP: Fuel Pump

FPM: Fuel Pump Monitor

GND: Ground

GRND: Ground

HEDF: High Speed Electro Drive Fan relay or circuit

KOEO: Key On Engine Off

KOER: Key On Engine Running

VOM: Analog Volt/Ohm Meter (see DVOM)

VPWR: Vehicle Power supply voltage (regulated 10-14 volts)

WAC: WOT A/C Cut-off switch or circuit

WOT: Wide Open Throttle

INTEGRATED RELAY CONTROLLER DESCRIPTION

The Integrated Relay Controller Module (IRCM) interfaces with the EEC-IV system to provide control of the cooling fan, A/C clutch, and fuel pump. The module incorporates the ECC power relay which supplies current to the EEC-IV system.

The location of the IRCM for all models is on the radiator support bracket. The operating voltage of the IRCM is between 7-17 volts.

For diagnostic information concerning A/C components controlled the IRCM and/or for the IRCM itself, see the following INTEGRATED RELAY CONTROLLER TEST CHARTS .