8206noco.fm Page 206 Thursday, July 2, 1998 1:19 PM
SYMPTOM RELATED DIAGNOSTICS ON/OFF FAN CONTROL VERBAL COMPLAINT (continued) Test 19 Checking for air supply — HORTON only 1. Crack the air supply line leading to the solenoid.
If air flows out of the supply line, proceed to Test 39. If air does not flow out of the supply line, there is a blockage in the supply line or some other air system problem. Locate and repair the problem. Retest to be sure the problem has been corrected.
If the fan cycles quickly, erratically, or is ON for long periods of time while the coolant temperature is below 170°F (77°C), and the connections to the harness, switch and ground are good, there is not a problem with the electrical and pneumatic portions of the fan control system. There may be a problem with the level of refrigerant charge in the system, a plugged condenser core, or elsewhere. Locate and repair the problem. Retest to be sure the problem has been corrected.
Test 34 Checking for a short to ground between the solenoid and the freon fan pressure switch
Test 22 Checking for correct plumbing of the solenoid 1. Tighten the air supply line. 2. Remove the vent cap or vent line from the solenoid.
If air flows out of the vent, the solenoid is plumbed incorrectly. Reverse the vent and air supply lines on the solenoid. Retest the fan drive. If air does not flow out of the vent, the solenoid is defective. Repair or replace the solenoid. Retest the fan drive.
Test 32 Testing for proper freon charge
If the fan cycles on a regular basis, proceed to Test 64. If the fan turns ON immediately after the engine is started and remains ON, never turning OFF, verify proper jumper connections to the harness, switch and ground. If the fan still does not turn OFF, visually inspect the pressure switch connector for dirt, wear, and evidence of an open connection. If there is no damage, replace the switch and retest the fan drive.
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Figure 326 — Continuity between Pin B and Ground
1. Check for continuity from pin B of the fan clutch solenoid engine connector to a good ground.
If there is continuity, the harness is shorted to ground between the fan clutch solenoid connector and the freon fan pressure switch connector. Locate and repair the short. Retest to be sure the problem has been corrected. If there is no continuity, the fan clutch solenoid connector is open. Visually inspect the connector for dirt, wear, and open connections. Retest to be sure the problem has been corrected.
