Radiator Fan not Switching On!

Post by **shiloh51933** » 29 Jul 2010, 10:41

My 96' 850GLT radiator fan will not turn when it should, I tried changing the relay on the fan shroud carrier. The temp gauge in dash cluster looks good, maybe temp sensor or switch?. I don't have OBD II to read ECU, so I have to do this by trial and error. Any suggestions/advice will be highly appreciated, thanks.

Post by **Ozark Lee** » 29 Jul 2010, 11:00

My 96' 850GLT radiator fan will not turn when it should

Does it turn on when the A/C is running? Otherwise it is not uncommon for the fan to not be on unless you are stuck in traffic.

...Lee

Post by **shiloh51933** » 29 Jul 2010, 19:11

AC off but the temp is running high and fan should be going on.

Post by **Ozark Lee** » 29 Jul 2010, 19:24

There are three connectors on the fan relay. The power connector, the control connector and the connector that leads to the fan. The center connector should have, as I recall, a yellow wire and a yellow/white wire. With the key in position II ground each of those connections, one at a time, on the relay side and see what happens. Off the top of my head I can't remember which wire is which fan speed but one should result in the fan being on low an the other should be the fan being on high.

If you pass that test then there may be a wiring issue between the ECU and the relay, a problem with the ECU itself (very uncommon) or a problem with the ECT sensor (more common). The most common problem of all is the fan relay itself.

Test the relay first with the grounding method.

Note: The connectors are tough to get off even after the release is pulled back but they will come off with a little gentle back and forth wiggling. I have pulled my relays out of the shroud to get better access to the connectors when I have had to mess with them.

...Lee

Post by **shiloh51933** » 30 Jul 2010, 14:56

Ozark Lee wrote:There are three connectors on the fan relay. The power connector, the control connector and the connector that leads to the fan. The center connector should have, as I recall, a yellow wire and a yellow/white wire. With the key in position II ground each of those connections, one at a time, on the relay side and see what happens. Off the top of my head I can't remember which wire is which fan speed but one should result in the fan being on low an the other should be the fan being on high.

If you pass that test then there may be a wiring issue between the ECU and the relay, a problem with the ECU itself (very uncommon) or a problem with the ECT sensor (more common). The most common problem of all is the fan relay itself.

Test the relay first with the grounding method.

Note: The connectors are tough to get off even after the release is pulled back but they will come off with a little gentle back and forth wiggling. I have pulled my relays out of the shroud to get better access to the connectors when I have had to mess with them.
...Lee

I replaced the fan relay to no avail, ECU checks out, seems like temp sensor wiring, probably will just replace.

Post by **drvolvo** » 30 Jul 2010, 21:25

I had a similar problem with a S40. They replaced all three relays but it did not solve the problem. I had already replaced the thermostat and those usual suspects. My problem was the resistor that controlled the radiator fans. My radiator fan would not come on at the low speed. Then the car would being to overheat and then the fan would kick on at the higher temperature, but by then it was too late. This problem always occurred when the AC was turned on, and it was really bad in traffic. So check your radiator fan resistor. It controls when the fan comes on.

Post by **shiloh51933** » 01 Aug 2010, 09:43

drvolvo wrote:I had a similar problem with a S40. They replaced all three relays but it did not solve the problem. I had already replaced the thermostat and those usual suspects. My problem was the resistor that controlled the radiator fans. My radiator fan would not come on at the low speed. Then the car would being to overheat and then the fan would kick on at the higher temperature, but by then it was too late. This problem always occurred when the AC was turned on, and it was really bad in traffic. So check your radiator fan resistor. It controls when the fan comes on.

U might be right, she doesn't come on at all, not using a/c though, stat looks good, probably somthing stup[id like the fan resistor. What did u do to resistor? replace,clean up what?

Post by **Ozark Lee** » 01 Aug 2010, 20:34

850's don't have a resistor for the radiator fan, the fan itself has two sets of windings, one for low speed and one for high speed, and the fan relay controls what it does at the direction of the ECU.

...Lee

lumberjackzac · Post by **lumberjackzac** » 02 Aug 2010, 00:59

sounds like my problem, would greatly appreciate the answer. Where and how?

Post by **shiloh51933** » 02 Aug 2010, 11:35

Ozark Lee wrote:850's don't have a resistor for the radiator fan, the fan itself has two sets of windings, one for low speed and one for high speed, and the fan relay controls what it does at the direction of the ECU.

...Lee

So I should inspect the windings or what?