AC Not blowing cold air

I recently had the crossover pipe seal on my 2004 BMW 745li replaced. Took them about a month and a whole lot of giving me the "running around." I got over it. Here's the problem. When I picked it up the "water coolant light" was coming on and mechanic said that it would be on but not to worry because the reservoir was adequate coolant. I said, okay.....didn't think that was a big deal so I decided to fix that later.

As I was driving home I decided to turn on the AC and come to find out NO COLD AIR was blowing. When I called the shop they told me that they didn't mess with anything related to the AC system. Basically they're not being responsible for those items. Even though, when I dropped off my car, no coolant lights were on and my AC was working adequately.

Does anyone here know what could have happened? Is there a wire or sensor that they could have disconnected or bumped or maybe messed with the compressor and didn't connect it back. The compressor seems to be turning on but no cold air. The auxillary fan turns on but not when AC is on.

Any kind of help I would greatly appreciate

Thank you.

Lawyer up. They definitely messed something up. Coolant pipe with no ac and lights. Call an attorney

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Yes I definitely thought about that already.... How would I prove that they caused it........that's my dilemma. I'm hoping someone here with those crossover pipe seal replacement repairs can possibly tell me if it is related.