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CollapsedNut
04-14-2012, 11:26 PM
So this is the cooling fan control on my Lancer. It's been acting up for awhile now, the fans just randomly come on and off as they please. If the fans are running and you tap on this box with something they will turn off. I was thinking I would find a relay inside, but I don't see one, just some caps and a transistor. There is a board underneath the first layer but I don't see anything down there that would respond to "tapping". What you guys think?

https://mail.google.com/mail/?ui=2&ik=1d9c84a299&view=att&th=136b2ec6ba4279bc&attid=0.1&disp=thd&realattid=1399263508348010496-1&zw
https://mail.google.com/mail/?ui=2&ik=1d9c84a299&view=att&th=136b2ecd79fd39bf&attid=0.1&disp=thd&realattid=1399263545216991232-1&zw
https://mail.google.com/mail/?ui=2&ik=1d9c84a299&view=att&th=136b2efbeab2332d&attid=0.1&disp=thd&realattid=1399263730941820928-1&zw

Galcobar
04-14-2012, 11:50 PM
Components integrated into a circuit board can come loose -- it's something I've become familiar with on computer graphics cards because they experience the most significant heat cycling. The heating/cooling cycles can crack the solder, producing an intermittent connection.

If you can find something loose, it's easy enough to correct with a soldering iron. Leave the cover off and next time the fans act up, try pressing -- tapping would transmit a vibration through the board to other components and produce a false positive -- on each component you can reach.

If not, and nobody else comes up with alternatives, you could try baking the electronics. Hold the board off a baking sheet with balls of aluminum foil, and put it in the over for 8-10 minutes at 200C (390F). Turn off the oven, and let the circuit board cool before you move it. You're essentially replicating the solder reflow ovens used to affix Surface Mount Technology components in the factory.

CollapsedNut
04-14-2012, 11:56 PM
I'm looking at getting to the board on the bottom layer, but I'm thinking it will be impossible. I can see screws on it but I can't get to them without desoldering the top layer and setting it aside.

CollapsedNut
04-14-2012, 11:57 PM
Hold the board off a baking sheet with balls of aluminum foil, and put it in the over for 8-10 minutes at 200C (390F). Turn off the oven, and let the circuit board cool before you move it. You're essentially replicating the solder reflow ovens used to affix Surface Mount Technology components in the factory.

Could I do this with the caps still in the board or would it make them go boom?

Galcobar
04-15-2012, 12:37 AM
I've not seen any issues with blowing capacitors reported, except for those semi-counterfeit Taiwanese ones which plagued the electronics industry for a few years in the 2000s and would blow if you breathed on them.

CollapsedNut
04-15-2012, 12:39 AM
I was just checkin some other stuff, the relay that powers this system seems to be being activated all the time, even when the fans are not running(even still, tapping the control box turns the fans on/off). That seems odd to me. I really need to get a real schematic on this but thats not easy to find for a Lancer cause Chilton nor Haynes make a book for them.

CollapsedNut
04-15-2012, 12:40 AM
I've not seen any issues with blowing capacitors reported, except for those semi-counterfeit Taiwanese ones which plagued the electronics industry for a few years in the 2000s and would blow if you breathed on them.

My cars an 02, that doesn't make me feel good!

UtahSleeper
04-17-2012, 07:19 PM
Maybe find a whole new unit at a junkyard? Do any other dodge's/Mitsu's use that box?