1999 S70 Radiator fan not turning on.

fresco · Post by **fresco** » 15 Oct 2019, 23:39

Replaced:
New thermostat
New ECT sensor

Water temperature gauge needle at 1/2 position (although suppose to be on red - new ECT and thermostat) since coolant is boiling, however fan does not go on. Turning AC on or off does not make any difference.

Unplugging ECT sensor turns the fan on. Plugging ETC sensor back on shuts down the fan.

Grounding yellow and yellow/white wire at the relay switch turns fan and low fan on.

Post by **abscate** » 16 Oct 2019, 02:40

Did you use a Volvo OEM sensor?

Known to be good: fan wiring, Ecm to fan relay wiring

Need more information on Conditions of coolant boiling over, the dash gauge isn’t a precision instrument. Think of it as a three led lamp; cold, correct, overheat

fresco · Post by **fresco** » 16 Oct 2019, 08:50

I got the sensor from auto supply store, need to ask them what brand that was.

Not sure how to answer the last question it is boiling over because fan will not go on at all, unless ECT is unplugged.

fresco · Post by **fresco** » 03 Nov 2019, 16:02

that was temperature sensor:

I have replaced it 3 times (all aftermarket $18.99, $26.99 and $7.99).
the ironic is that the one that finally worked was purchased on amazon for $7.95...
sold by Dade-US

https://www.amazon.com/gp/product/B01FU ... UTF8&psc=1