Radiator Fans Not Working

counselorm24 · Post by **counselorm24** » 18 May 2020, 22:02

Hello All,

Troubleshooting a new issue with my 1996 850. I have purchased a brand new Volvo fan controller and a brand new fan. I've finished hooking it all up tonight and the fan still won't kick on. I've tried unplugging the middle connector (ground signal to turn on relay to send power to fan) and i can hear and feel the click of the relay activating, so i assume it's getting ground from the ECU or something to turn it on. I've also verified that voltage come out of the output of the relay to go to the fans. The one thing i haven't closely traced and checked is the ground for the fan motor.

I thought about the ECT, however the temp gauge shows normal readings on the dash.

Now, assuming that the ground tests out OK and a bypass doesn't engage the fan, Does anyone have any advise of what to do or look for next?

Thank You,
Michael

Post by **ZionXIX** » 18 May 2020, 22:27

Have you tried powering the fan directly from the 12v system? Is your coolant temp sensor good?

counselorm24 · Post by **counselorm24** » 19 May 2020, 09:33

The fan does function when hooked up to the battery direct. I am assuming the coolant temp sensor if good, as I show accurate temp reading on the temp gauge. Is there still a possibility this sensor could be bad? If so i can change it out, not to mention, i can tell the relay is clicking on with a signal from the ECU, so the issue might lie in the power supply to the relay/fan or the ground.

Is there a fuse or relay for the fans? If so, where are they located?

Also I think my voltage when the car is running might be slightly low, could this be causing the issue as well?
I will have it checked by the local AutoZone when i get out of work, I think the alternator has been recently replaced, so I might replace some old wires to/from the unit.

When the relay or fan is disconnected from any of the wires and plugged back in when the car is running and up to temp. I will see the fan jerk slightly, but never spins.

Thanks
Mike

Post by **scot850** » 19 May 2020, 10:42

The connector to the fan from the ECT is notorious for issues. The connector for the ECT is normally mounted at the back of the power steering pump. The wire from there to the operate the the fan and relay may have a bad connection at this point or may be broken. So check the continuity from the connector on the power steering pump to the relay.

The ECT itself may be reading just fine otherwise in the car. It is just the signal wire to the fan that is the problem.

Neil.

Azik09 · Post by **Azik09** » 19 May 2020, 11:12

Check fan's ground. If relay have not powered, you couldn't hear click when connect any of middle pins to ground. Fan is grounded to cylinder block near starter motor by separate black wire.
Simple fan test: disconnect ECT and start the engine. Fan should start immediately. If so, all fan's circuits are OK

counselorm24 · Post by **counselorm24** » 19 May 2020, 11:29

Sounds good!

I'll test the ground and ECT and let you know the results.

Thank You
Mike

counselorm24 · Post by **counselorm24** » 19 May 2020, 17:59

Hello All,

I've tested the power and ground to the relay and it is good, I've also applied the ground to the two relay control pins and get good high and low speed operation.

I've hooked it all back up, started the car and turned on the AC full blast but no fan operation.

When I unplug the ECT, the fans kick right on high, but the car also runs worse, and I still have normal temp readings. Is there another temp sensor somewhere?
When I plugged the ECT back in the car runs better, and I'm getting low speed fan operation. Maybe a bad connection on the ECT?
I've ordered a new ECT anyhow.

Let me know what you all think
Thanks for the info!
Mike

PS: Can someone send a picture of the wire color vs it's position in the middle connector of the fan relay? I removed them to clean them, but forgot to keep track of where they went.

Azik09 · Post by **Azik09** » 20 May 2020, 00:00

Looks like ECT is defective...
There is only one temp sensor.
Fan relay middle connector: pin#1 - yellow/white
pin#2 - yellow

Post by **Chuck W** » 20 May 2020, 15:20

Clean that ECT connector.

counselorm24 · Post by **counselorm24** » 22 May 2020, 09:55

Hello All,

The new ECT is on it's way in today. I'll clean the car side connector before installing it and let you all know how it goes.

Thanks for all the suggestions!
Mike