blower motor auto postion not working 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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1997 - 2000 V70, V70 AWD
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blower motor auto postion not working

Post by Jaumme »

when i place the blower motor in auto mode the blower motor and the entire climate control components stop working, i have 3 ecc one is dead because the damper motors wont work with this one but the auto in blower motor is working. the other 2 are working perfect but the auto blower is not working i didnt find any information about that, anyone knows something?

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Post by jreed »

You could open up the ECC unit and inspect the components inside for damage. Some people have reported damage to the circuit board, capacitors, diodes and other components on the board. While you have it open, you could also test the sliding switch to see if the switch is working correctly when you slide it all the way over to "AUTO" mode.
Have you tried to connect a code reader to the ECC unit to check for error codes? That may provide clues about what is not working correctly. See for example: viewtopic.php?f=1&t=64888
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Post by RickHaleParker »

Unit #1: Auto works Dampers do not.
Unit #2 & #3: Dampers works but Auto does not.

Clearly the external circuits are all working. That leaves only two possibilities, you have three defective ECC units or some of them are defective and the others are the incapable reversions of the ECC. There are 10 revisions of the 850 ECC.
The '93 850s used ECC revisions 2 - 5.

Read this thread.
Last edited by RickHaleParker on Tue Jun 18, 2019 12:21 pm, edited 1 time in total.
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Post by jimmy57 »

The early versions require a ground signal on one of the pins supplied by ignition module or the Motronic ECM if 94 turbo (I don't remember the numbers but I have answered this several times and listed the pins.) and the later are designed to get engine running info from alternator charge light circuit as an engine run signal. The simple fix for the early ones is to cut the wire behind the ECC module and ground it. If you search you should find the earlier replies with pin and wire color info.

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