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Radiator Fans Not Working

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

counselorm24
Posts: 14
Joined: Fri May 08, 2020 7:15 am
Year and Model: 1996 850
Location: Johnston, RI
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Radiator Fans Not Working

Post by counselorm24 »

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
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ZionXIX
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Joined: Mon Aug 11, 2014 2:47 pm
Year and Model: 1996 850 Turbo S/W
Location: Texas
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Re: Radiator Fans Not Working

Post by ZionXIX »

Have you tried powering the fan directly from the 12v system? Is your coolant temp sensor good?
counselorm24
Posts: 14
Joined: Fri May 08, 2020 7:15 am
Year and Model: 1996 850
Location: Johnston, RI
Has thanked: 10 times

Re: Radiator Fans Not Working

Post by counselorm24 »

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
scot850
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Re: Radiator Fans Not Working

Post by scot850 »

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.
2000 V70 R - still being an endless PITA
2006 XC70
2003 Toyota 4Runner V8 Limited
2015 Kia Sportage EX-L
1993 850 GLT -Sold
1998 V70 XC - Sold
1997 Volvo 850 SE NA - Went to niece in California - Sold
2000 V70 SE NA - New project and test bed - Sold
Azik09
Posts: 65
Joined: Thu Sep 11, 2014 2:08 am
Year and Model: S70 T5, 1997
Location: Russia, Caucasus
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Re: Radiator Fans Not Working

Post by Azik09 »

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
If my English is bad, please correct me :oops:
counselorm24
Posts: 14
Joined: Fri May 08, 2020 7:15 am
Year and Model: 1996 850
Location: Johnston, RI
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Re: Radiator Fans Not Working

Post by counselorm24 »

Sounds good!

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

Thank You
Mike
counselorm24
Posts: 14
Joined: Fri May 08, 2020 7:15 am
Year and Model: 1996 850
Location: Johnston, RI
Has thanked: 10 times

Re: Radiator Fans Not Working

Post by counselorm24 »

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. :roll:
Azik09
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Joined: Thu Sep 11, 2014 2:08 am
Year and Model: S70 T5, 1997
Location: Russia, Caucasus
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Re: Radiator Fans Not Working

Post by Azik09 »

Looks like ECT is defective...
There is only one temp sensor.
Fan relay middle connector: pin#1 - yellow/white
pin#2 - yellow
If my English is bad, please correct me :oops:
Chuck W
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Re: Radiator Fans Not Working

Post by Chuck W »

Clean that ECT connector.
'97 854 T5 - Manual Swap, M4.4,COP, P2R Brakes, 16T, chassis bracing, XC70 nose swap
'97 855 GLT - Hers. RN swap/16T/exhaust/302s/Flashable M4.4, chassis bracing, 2 kid seats
'78 GLE - Waiting in the wings. Future whiteblock/T5 swap.
counselorm24
Posts: 14
Joined: Fri May 08, 2020 7:15 am
Year and Model: 1996 850
Location: Johnston, RI
Has thanked: 10 times

Re: Radiator Fans Not Working

Post by counselorm24 »

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
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