Mercedes: Mercedes 1978 300d diesel, copper tip, fuse holder

Question
hello. My Mercedes has been having some power windows issues and i was wondering since my took out my thermostat with out taking off the negative cable will that cause a short in the system and plus he still hasn't replaced the thermostat.... so if you got any suggestions that might help that will be great. Thank you for your time.

Answer
Patrick,
What do you mean buy "issues"?  Do not work... work intermittently? will not go up, down?
Door switch or console switch rear or front? both?

Power windows issues are usually related to bad connections and or grounds or bad switches.
During the thermostat removal, you may have moves some wiring or harness connections that were corroded.
Begin with fuse holder and fuse. Throw away any aluminum fuses and replace with copper. Polish the holder and the copper tip of the use.
High resistance at any grounding point or power connections, can keep the windows from working. Clean any obvious connection that looks corroded.
Good Luck
Rob