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'96 850 Heater Blower Motor, or Relay? Topic is solved

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
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ToriWhite
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'96 850 Heater Blower Motor, or Relay?

Post by ToriWhite »

I have a number of specific symptoms and I hope someone who has experience with wrestling their climate control system can weigh in here

- Climate control fan does not turn on
- Both dials for 'intensity' seem to do nothing
- Selecting fan speeds 0-3 do nothing, de/selecting speed 4 will make a small motor actuating sound from deep inside the dash
- Same sound will occur when de/selecting the Recirculate switch
- Little snowflake button makes no sound
- Little arrow wiggly switch next to Sunroof button (Defrost for windows, rear glass?) will change the pitch of the fuel pump hum, presumably it's articulating something I can't hear
- Center knob for selecting what vents are controlled (Defrost, face, face+feet, feet) is binding, will not deselect off of Defrost
- Cabin will heat up with the car engine, heat's up an order of magnitude faster/hotter with all vents open

I think I pulled a spare climate control panel last time I was at the yard, if that can help with troubleshooting. Does this look like anything specific? I've read a lot about people losing fan speed 4 and keeping 0-3 - but I haven't found anything that quite fits what I've got yet
ToriWhite
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Re: '96 850 Heater Blower Motor, or Relay?

Post by ToriWhite »

Apparently I have an MCC unit, and this is what one looks like, as opposed to an ECC unit
I will test if my fuses are being blown, I was wondering why I pulled an extra CC panel last time, maybe it was because I saw this video and wanted to test this, and then forgot about it- who knows! It'd be nice if I could repair this without having to dig into the actual motor..!

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Re: '96 850 Heater Blower Motor, or Relay?

Post by abscate »

The manual system is rare over here in the states, be careful with that control unit as it’s very expensive and the grifters on eBay know this and have jacked up the price if the used ones.

It is easy to fix the cables , and worst case you can activate them under the dash like they do on budget airlines when they break.

The unit comes out differently than the electronic one. You first remove the knobs, then ease out the Torx screws, remove the rear face plate, the clips to release e the front of th e control unit.

Remember front and rear refer to car, not the driver perspective

Found a thread with some pictures from April 2019

viewtopic.php?f=1&t=89316&p=517711&hili ... ol#p517711
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ToriWhite
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Re: '96 850 Heater Blower Motor, or Relay?

Post by ToriWhite »

Fuses:
Fan Motor speed 1-3 25a Fuse, Good
Fan Motor Speed 4 30a Fuse, super dead

Removed suspect switchpack Robert was talking about in video above, Fan Motor Speed 4 30a fuse doesn't fry on cycling between fan speeds.. but the blower motor doesn't turn on either. Go figure. Digging around in my 'Pick n Pull Booty' pile, I somehow have 3 of those switchpacks.. when are we going to make a members only trade page of "Parts you can have if you pay for shipping?"

Considering I've got a good fuse and current running to the motor for speeds 1-3, but no blower motor action.. plus a burnt 4th.. wouldn't that point to a seized blower motor? My thinking is speeds 1-3 are 'trying' but not doing anything, 4th 'tried', but at that high power somethings gotta give, and that something was the fuse

There's apparently a Resistor under the glovebox, wired inline to the blower motor. I imagine that's only relevant to the fan speeds 1-3? I keep seeing it as the culprit when the symptoms are "Fan only blows on speed 4, not 1-3" whereas I've got all speeds dead.
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Re: '96 850 Heater Blower Motor, or Relay?

Post by BEJinFbk »

Speeds1-3 on MCC run through the fan speed switch
and then through the selected resistor in the resistor-pack.

When you flip into the speed 4 position, a relay next to the
blower motor bypasses all of that and provides a direct set
of relay contacts for “Full Speed, no resistors at all” operation.
'98 V70 R - Well Equipped for Life Up North... ;)
ToriWhite
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Re: '96 850 Heater Blower Motor, or Relay?

Post by ToriWhite »

I've been reading more about said resistor .. it appears the two possible points of failure for me are the Resistor, or Motor- (either the motor seized on its own, or the relay got borked and burnt it out?) I'm going to pull and test resistor, motor - prod every component on every setting of my multimeter and hopefully glean something important
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Re: '96 850 Heater Blower Motor, or Relay?

Post by BEJinFbk »

Have you unplugged the motor and
applied battery voltage directly to it?

That will bypass all the other stuff and
at least give you an idea of what kind of
shape the motor is in.
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Re: '96 850 Heater Blower Motor, or Relay?

Post by Klausc »

If you remove the cover under/in front of the windshield, you will be able to see the blower. You could reach down and see if it turns easily.

Otherwise remove the glovebox to gain access to the blower box and verify that the wires are not melted. Replacing the blower is not a difficult job.
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Re: '96 850 Heater Blower Motor, or Relay?

Post by BEJinFbk »

Maybe this will help?
95 850 MCC Wiring Diagrams.pdf
(450.04 KiB) Downloaded 11 times
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ToriWhite
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Re: '96 850 Heater Blower Motor, or Relay?

Post by ToriWhite »

I have removed the blower motor from under the glovebox. Warning to anyone reading this in the future : That knee bolster has some sharp edges!

I now have the motor free and on my desk, and am going to try and troubleshoot it. The housing it sat in was clean, unfortunately. I was kinda hoping that the air filter fell apart, and the rubber gasket was binding it up - so I'd just be able to clean it out and switch it on.
Klausc wrote: Mon Mar 16, 2020 7:56 pm ... You could reach down and see if it turns easily.

Otherwise remove the glovebox to gain access to the blower box and verify that the wires are not melted...
It doesn't spin freely, but it moves. Feels a little bindy.
Wires didn't look melted- just hilariously dusty.
BEJinFbk wrote: Mon Mar 16, 2020 6:57 pm Have you unplugged the motor and applied battery voltage directly to it?
I have not, yet. Would this be accomplished just connecting the battery to the motor's two tabs (pictured below)? Do I have to respect polarity, or is this that type of motor that can be ran with current going either direction? They had a plug on it, there were lots of plugs on the motor, could I accomplish this just plugging the one that affixes to the tabs, and firing it up?

(Thanks for the wiring diagram PDF BEJinFbk, that will help!)
IMG_8923.jpg
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