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| Black 1997 Volvo 850 Right Side View |
I have problems with my 1997 Volvo 850 radiator fan. The radiator fan won’t work and it doesn’t receive signal from the ECU. can anybody help me?
Answer: OK here is how the system actually works:
1. Coolant temp sensor [located below thermostat housing at top front of engine.
This is a single sensor system, this sensors information is shared with engine fuel management transmission computer and instrument cluster.
2. The engine management computer has total control over the cooling fan.
Noting that this achieved by means of a fan relay located low, on the right side of the radiator core support. This relay is hard wired to the fan itself and the fan and relay are replaced as a unit.
When an 850 comes in with customer complaint[s] of running weird, cooling fan stays on or fan never comes on and or temp gauge fluctuates I check for codes [early models] or check the live data coolant temp of later models [obd 2] always I find the temp sensor is out of range .
Replacement is easy AFTER engine cools down remove the thermostat housing, thermostat and seal. Disconnect the sensor wire and remove/replace the sensor.
Reassembly should also consist of renewing the thermostat and seal at the same time. [never let the 850 engine overheat and always keep the timing belt and belt drive system fresh]
Over the years I have only had to replace 2 cooling fan/relays one due to crash damage and one on a very high mileage car that just quit [vehicle in question had 320k miles on it].
1. Coolant temp sensor [located below thermostat housing at top front of engine.
This is a single sensor system, this sensors information is shared with engine fuel management transmission computer and instrument cluster.
2. The engine management computer has total control over the cooling fan.
Noting that this achieved by means of a fan relay located low, on the right side of the radiator core support. This relay is hard wired to the fan itself and the fan and relay are replaced as a unit.
When an 850 comes in with customer complaint[s] of running weird, cooling fan stays on or fan never comes on and or temp gauge fluctuates I check for codes [early models] or check the live data coolant temp of later models [obd 2] always I find the temp sensor is out of range .
Replacement is easy AFTER engine cools down remove the thermostat housing, thermostat and seal. Disconnect the sensor wire and remove/replace the sensor.
Reassembly should also consist of renewing the thermostat and seal at the same time. [never let the 850 engine overheat and always keep the timing belt and belt drive system fresh]
Over the years I have only had to replace 2 cooling fan/relays one due to crash damage and one on a very high mileage car that just quit [vehicle in question had 320k miles on it].
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