Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSFORD1997EXPLORER 4D UTILITY, 4.0 E, 4WDREPAIR AND DIAGNOSISHEATING, VENTILATION & A/C (HVAC)HVAC CONTROL SYSTEMSHVAC SYSTEM - A/C-HEATER SYSTEM - MANUALCOMPONENT TESTSISO RELAY TEST
1997 Ford Explorer 4D Utility, 4.0 E, 4WD
ISO Relay Test
1997 Ford Explorer 4D Utility, 4.0 E, 4WDSECTION ISO Relay Test
NOTE:
ISO (International Standardization Organization) has established standards in relay design. A/C system uses both a 4-pin and a 5-pin ISO relay. See WIRING DIAGRAM . Testing for both relays is identical, except when testing a 4-pin relay, pin 87A should not be tested.
- Remove relay from connector. Using a DVOM, check resistance from terminal No. 85 and each terminal of relay. See Fig 1. If resistance is 5 ohms or less, between terminal No. 85 and any terminal, replace relay.
- Using jumper wires, connect terminals No. 30 and 86 to positive battery terminal. Using DVOM, check for voltage at terminal 87A. If battery voltage is not indicated, replace relay. If battery voltage exists, connect a jumper wire between terminal No. 85 and ground. Check for voltage at terminal No. 87. If battery voltage is not indicated, replace relay.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.