Pulled a 190E cruise amp from JY and it does not work. I normally pull 190E cruise amp as it is very easy to access ( in front of passenger side carpet ) and a lot of the time works good. I find the 190E cruise amp will work with 300SDL and W124 300D. Have not tried the W123 300D but I would expect it will work too.

I replaced the 2 x 22uF capacitors as circled in picture and it works like new. What I find is that an intermittent unit is hard to fix as it is probably due to dry solder joints. Difficult to locate and hard to prove. This one is completely dead and the culprit is the 2 capacitors. Hope this help the motivated DIY guys.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.