405 L4-1905cc 1.9L (1989)
Technical Service Bulletin # 429911001
Date: 911001
Engine Cooling Fan - Operation
BULLETIN NO. 429
DATE:
OCTOBER, 1991
SUBJECT:
ENGINE COOLING FAN OPERATION
MODELS:
ALL 405 VEHICLES
The purpose of this bulletin is to give dealer service technicians information pertaining to the operation, troubleshooting and checking of the engine
cooling fan system on 405 vehicles.
I.Normal Operating Principles of the Engine Cooling Fan
With A/C off.
-
Both cooling fans engage at low speed when the engine coolant temperature reaches
98~C (208~F). In most instances, low speed operation will be sufficient to cool down the engine and the fans will disengage at 93~C
(199~F).
-
If the coolant temperature continues to rise during low speed operation, both cooling fans will engage at high speed when the temperature
reaches 102~C (216~F) and disengage totally at 97~C (207~F). The fan cycle will start again at low speed when the coolant temperature
reaches 98~C (208~F).
With A/C on:
-
Both cooling fans operate constantly at low speed.
-
Both cooling fans engage at high speed when the engine coolant temperature reaches 102~C (216~F) and return to low speed at 97~C
(207~F) as long as the A/C compressor is cycling "on."
NOTE: The coolant temperatures indicated above are recorded at the cooling fan temperature switch. The dashboard temperature gauge and the cooling
fan ECU receive their inputs from two different sending units. Due to operating tolerances, the temperature showing on the dashboard gauge may not
exactly correspond to the temperature input recorded at the cooling fan temperature switch.
II.Troubleshooting Engine Cooling Fan Problems