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94 850 Wagon Max Fan Relay Hot, 4 speed 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

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94 850 Wagon Max Fan Relay Hot, 4 speed not working

Post by 850heat » Mon Nov 25, 2019 6:32 pm


My 94 850 wagon (with the MCC) has always worked on blower fan speeds 1-3, but never worked well on fan speed 4. By pulling the max fan speed relay from behind the glovebox and putting it back in, I can get speed 4 back for a short while, but usually after a few minutes it will stop. I've recently noticed that the relay gets very hot after these few minutes, plug 87 is a bit charred. Please see pictures.

Is there an obvious reason why its doing this? I tried replacing the relay but it did not solve the problem. Is there an issue with the resistor?



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Re: 94 850 Wagon Max Fan Relay Hot, 4 speed not working

Post by RickHaleParker » Tue Nov 26, 2019 12:26 am

Speeds 1, 2, & 3 are controlled by the resistor pack. Speed 4 switches on the relay and connects the fan motor directly to the Battery.

Check the relay socket, what condition is it in?

Probably overheat and burn like the relay terminal. You pull the relay out and reinsert, you get a good connection until it burns up again.
2019-11-26 (3).png
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Platform: P80 1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package, Plant: Uddevalla Sweden.

Platform: X40 (Nedcar) 2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000. Plant: Born Netherlands.

Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0,
Plant Torslanda Sweden.
1997 S90, B6304S, AW30-42, Bosch Motronic 4.4 - Sold

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Re: 94 850 Wagon Max Fan Relay Hot, 4 speed not working

Post by BEJinFbk » Tue Nov 26, 2019 1:03 am

Sounds like you need to replace both the relay and socket.
You may also have a worn blower motor issue that caused
your relay/socket problem. How old is that motor?

'98 V70 R - Well Equipped for Life Up North... ;)

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