I have a problem which I believe is in the pbc (push button control) on my automatic control unit
The fan wont work sometimes, but if I lower the round temp to min it works, only to not work when set to a temp.
After moving the temp switch up and down and pushing the buttons and adjusting the fan setting from high to low and back to automatic I can get it to work on auto agian.
I have read the DYI section which describes the problem in the early 126, with poor connection between the temp control switch and also poor soldering points.
My question is if I pull the pbc out where and how do I start to improve the connections.
Thankyou Mark

Use a solder iron to heat the terminals and put a dab more of new solder on it.

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Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS

I second that motion! Benzmac said it all. i fixed my climate control last weekend by doing the same as described above. although there is a 50% chance that this will solve your problem it is well worth it. why sped hundreds of dollars when you don't have to.
Good luck and keep us posted!
Adam

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Current Stable:
01 ML55 AMG
92 500E (a few mods)
87 300E (lots of mods)
00 Chevy 3500HD Diesel Box Truck
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PREVIOUSLY OWNED:83 300SD, 87 420SEL, 88 420SEL, 90 420SEL, 86 560SEL, 86 190E 2.3-16V AMG, 94 E320

Thanks for your support I will give it a go today and let you know how I get on,
Mark

I started with the main terminals on the thermo switch, resoldered them making sure to get a good contact to the curcuit board.
Then moved to the main curcuit board on the pbc resoldered any points that looked suspect, about thirty in all.
Re-installed it. Total job time about 35 minutes taking it slow and easy.
And Hey Presto. It worked beautifully.
Thanks everyone my most annoying problem gone.
HOOOOOORAAAAAAAY