bchulett
NAXJA Member #999
- Location
- Southern California
According to the 1991 Jeep FSM, the Auxiliary Fan on a XJ switches on and operates when the air-conditioning is used ... or when the AC is off, the coolant temperature reaches 190°F.
Background:
1. The Aux fan works when I turn on the AC.
2. The Aux fan does not come on until the coolant temp hits about 215°F.
3. The dealer tells me the Aux Fan comes on at 215°F ... but I have reason to believe they're incorrect.
When my XJ was new, the Auxiliary Fan would switch on and operate exactly per the instructions in the FSM ... right when the temp reached 190°F. I would hear it come on.
I've suspected for years the cooling temp sensors may be faulty ... the only problem is the FSM is unclear which cooling temp sensor is ultimately wired to the Aux Fan ... the sensor in the "Block", or the sensor in the "Thermostat Housing".
The only thing the FSM says is the Aux Fan is turned on by the "engine controller" through a relay located in "power distribution center"---Okay ...
BUT ... the FSM covering the "Engine" under section "Cooling System" only references a sensor in the "Block" .... and the only place I can find reference to a sensor in the "Thermostat Housing" is in the FSM covering "Electrical, Heating-A/C & Emissions" under section "Ignition"---neither describes the Aux Fan and sensors in-depth.
Questions:
1. Any ideas what cooling sensor tells the engine controller "I've reached 190°F" ... so the Aux Fan will switch on and start blowing wind ??
2. Why is a cooling sensor in the "Thermostat Housing" referenced in the "Ignition" section of the FSM ?
This is probably clear as mud ... but any help would be appreciated.
Background:
1. The Aux fan works when I turn on the AC.
2. The Aux fan does not come on until the coolant temp hits about 215°F.
3. The dealer tells me the Aux Fan comes on at 215°F ... but I have reason to believe they're incorrect.
When my XJ was new, the Auxiliary Fan would switch on and operate exactly per the instructions in the FSM ... right when the temp reached 190°F. I would hear it come on.
I've suspected for years the cooling temp sensors may be faulty ... the only problem is the FSM is unclear which cooling temp sensor is ultimately wired to the Aux Fan ... the sensor in the "Block", or the sensor in the "Thermostat Housing".
The only thing the FSM says is the Aux Fan is turned on by the "engine controller" through a relay located in "power distribution center"---Okay ...
BUT ... the FSM covering the "Engine" under section "Cooling System" only references a sensor in the "Block" .... and the only place I can find reference to a sensor in the "Thermostat Housing" is in the FSM covering "Electrical, Heating-A/C & Emissions" under section "Ignition"---neither describes the Aux Fan and sensors in-depth.
Questions:
1. Any ideas what cooling sensor tells the engine controller "I've reached 190°F" ... so the Aux Fan will switch on and start blowing wind ??
2. Why is a cooling sensor in the "Thermostat Housing" referenced in the "Ignition" section of the FSM ?
This is probably clear as mud ... but any help would be appreciated.