The current drawn is small in compressor. It should be similar between R4 and Sanden. It is used to activate the coil only. Info from Internet.

.The A/C clutch coil is acceptable if the current draw is 2.0 to 3.7 amperes at 11.5 -12.5 volts
at the clutch coil.
· If the current is more than 4 amps, the coil is shorted and should be replaced.

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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.