Need to find what person did to undo. on 1999 Chevrolet Blazer

Needed a new heater/ac control. Took it to a/c repair place and they rigged it for $150.00; now I got a new heater/ac control and trying to find out what he did, so I can undo it. OR pay $150.00 for him to undo it! Need help! Thank you !!

Asked by for the 1999 Chevrolet Blazer
This is a very difficult question to answer without seeing what the shop did to it. What was the end result of what the shop did? Did they make it so the A/C would work? Blower fan? Have you removed the controller to see if there are any modifications to the wiring?
Shop rigged it so the heat would quit blowing and the a/c to work. They said heater/ ac control was bad so I finally got one and put it in. Seen no wires switched, but think that's what they did. If I had a wire digram I probably could switch it back, but local dealer don't have it and not trying to pay $50.00 for one online. Thank you for your help!
You can get a diagram for less (currently $10.50) if you get a one week subscription here:
If the wiring is modified it should be fairly obvious. Look for splices, crimps and other bridging type of connectors.
You can try talking to the shop that did the work, ask them what they did. Or will they only do it for $150?