Got the following faults which all happened at the same time

ESP Light on
Fan Runs constantly
Heater/Air Con does not work/switch on

and mechanic wants to do continuity checks on the wiring looms under the carpet, and I'm thinking the carpet will never fit the same again, any comments?

ps: He did a Fault code check and it came up with P1857, which doesn't pin point anything.

What would you consider?