Hi Don & mbdoc, (still wonder How to test) Are the Condenser AUX Fans regular DC motors that 12-14 volts will make spin? See a sticker L76A25 12V---> on fan. Was tricky to unplug or pry loose plug by resistor. My replacements do nothing at 12V, an original is smashed. I see the shroud is a horrible bug & dirt trap. Got plastic off removing pins from expanding pegs. Found it was full to fan opening and into motors with dirt and bugs. A vacuum clean compressed air job to plastic box would make air flow better! - '94 e320 w124 Thanks.