Initial Inspection and Diagnostic Overview

GENERAL DIAGNOSTIC INFORMATION COOLING FAN LOGIC
There are two cooling fans-a pusher and a puller. The fans run together at three different voltage levels to create three speeds or stages.
^ Low speed-both fans in series-6 volts each.
^ Medium speed-both fans in parallel with resistor in series-9 volts each.
^ High speed-both fans in parallel without resistor-12 volts each.
The fan speed selected is based on coolant temperature or A/C system high side pressure.

Low Speed
^ Enabled if coolant temperature exceeds 96° C (204° F) or A/C system pressure exceeds 1199 kPa (174 psi).
^ Disabled if coolant temperature goes below 92° C (198° F) and A/C system pressure goes below 799 kPa (116 psi).

Medium Speed
^ Enabled if coolant temperature exceeds 99° C (210° F) or A/C system pressure exceeds 1695 kPa (246 psi.)
^ Back to Low speed if coolant temperature goes below 97° C (207° F) and A/C system pressure goes below 1399 kPa (203 psi).

High Speed
Enabled if coolant temperature exceeds 102° C (216° F) or A/C system pressure exceeds 2398 kPa (348 psi).
^ Back to Medium speed if coolant temperature goes below 100° C (212° F) and A/C system pressure goes below 2198 kPa (319 psi).