850 Blower power stage schematics

[lulucz]

Hi,

my blower power stage died, I tried to replace the mosfet transistor, but It still doesn’t work, so there are probably more problems on the board. Is there any chance that any of you has schematics for the board? Or any experience of what components on the board are prone to failing? Any information would be great, because it is hard to get a working module these days. My board is ANJ97010H.

Thanks,

Lukas

[scot850]

There have been a few threads on repairing ECC units on the forum over the last few years. I'm having trouble finding one I recall just now.

When you call it a power stage, do you mean what is commonly (and possibly wrongly) the resistor pack?

Is the car ECC or MCC controlled (Electronic or Manual). What is the part number of the Power stage?

Neil.

[yanga001]

I had an issue with my MCC previously which was just bad solder joints at the big through hole terminal block that connected to the board. Symptoms were the car ignoring the position set for the blower mode (down, up, defrost). Applying pressure to the module would periodically engage the blower. The symptoms may vary depending on which joints went cold. The fix was to reflow the connector which sorted the issue on the car.

edit:
my car was a 98 v70 base

[hausmeister]

I replaced mine with a pricy new one from skandix (9134932) was around 100€, though wow, that now costs 400+€, wtf!

Did also replace the mosfet on the old one, but I did not test it as I did not want to take everything apart again. But I did keep it, knowing these will be harder to find. Sorry, can't help with schematics.

[lulucz]

Thanks for all the replies, the system is ECC, so yes, it is the module that is often called resistor, but it is not, it is pretty complex circuit that controls the blower motor speed, In MCC there was I believe a module with just beefy resistor to control the motor speed. The ECC power stage module (I think it is called like that in VIDA) is very hard to get these days and is expensive. It is alsi prone to fail, so It would be super cool if someone wold be able to reverse engineer it to get the idea how the circuit works and eventually draw schematics wich I believe is not that complicated for experienced electronics engineer. From what I know there were more versions of the unit, but i think that the function is the same. There are two OP Amps, few transistors and one power mosfet.. I think I went trough all threads about this module aroud the net, but no schematics. Any progress would be great...

[scot850]

They are hard to find. What is the part number? I have a several I have collected over the years. Shipping cost is the main issue to Poland.

Is this the item and part number?

https://www.ebay.com/itm/386108567760

Neil.

[RedBrickCollector]

It is alsi prone to fail, so It would be super cool if someone wold be able to reverse engineer it to get the idea how the circuit works and eventually draw schematics wich I believe is not that complicated for experienced electronics engineer. From what I know there were more versions of the unit, but i think that the function is the same. There are two OP Amps, few transistors and one power mosfet.. I think I went trough all threads about this module aroud the net, but no schematics. Any progress would be great...

This sounds like a possibility like the fuel pump control module (fuel pump relay) deep dive. I don't want to volunteer anyone but I am interested as well.

[scot850]

This sounds like one for Mr. Al !! He and others did a great job on the fuel pump relay.

Neil.