Measure the resistance of the 2 prongs with a multimeter. It is a normally open thermo-switch. It should be open circuit at room temperature, close at 105C ( grey color ). You may have a bad wiring within the 2 prong plugs. It is too much of a coincidence that the thermo-switch broke while you were changing the fuse. One of the wire contact is chassis, the other goes to a relay inside the fuse box.

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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.