A/c not working after installation of a rebuilt engine

we have a 2007 toyota camry 2.4l which had a engine problem so car needed a rebuilt engine. so we went to auto repair shop and they installed a rebuilt engine.
But when we went to pickup the car the owner of the shop said our a/c is not working and he doesn’t know why. he said its a/c compressor clutch is not working. the a/c was working fine before the engine installation. when I talk to other people (different mechanics) they all say that the repair shop who installed the engine caused the a/c problem. how can I prove that so I maybe can sue the guy in a small claims court? for a good guesture the owner of the shop offered us free labor on installation of a/c compressor but not on part which I can bring my own. I need detail argument. people say that in order to win in a small claims court we need many supporting explanation from experts. we just want the a/c to work again. car drives fine after new rebuilt engine.
tia

This question will be near impossible to answer as no one here can possibly know why the A/C is not working.

Before even making a wild guess one would need to know how the engine was swapped out and the A/C compressor situation was handled.
In some cases the compressor can be unbolted and left in place in the engine compartment as is with a full refrigerant charge.
In other cases the hoses are disconnected after the refrigerant is evacuated, the engine removed with the compressor attached, and the system recharged once the engine (with compressor attached) is reinstalled.

You state this is a new rebuilt engine. Just to clarify something and remove all doubt I might ask this.
Does new rebuilt mean just that or does it mean a used low miles engine with another compressor attached to it?
I ask this because many people confuse the two and it muddies the water a lot.

It could be a simple overlook, it could be something so much more, Now just to let you know I hate suing people as my first line of defense for a problem. Now you have a problem, what to do? Take it to an ac specialist, some times a motor is interchangeable, but accessory parts are not. The ac specialist will diagnose the problem, and my guess it will be of minimal cost. Sure you have a problem, but I hate making lawyers rich and defendants poor when there are other solutions.

Take it to an AC specialist and pay for a diagnosis and get estimate for repair.

You always ask the engine shop to either pay for repair or perform it.

If not have it repaired at AC place and then you go to small claim courts and try to get your money back if the judge feels you proved your case. Sorry about your woes.

This is a wild guess, but I wonder if there is supposed to be a ground strap between the engine and the chassis that wasn’t installed when the engine was replaced. If the compressor clutch grounds through the bracket which is attaxhed to the engine, that would explain it. This,would be an easy fix. I would recommend a,shop that specializes in electrical problems. This,should be an easy troubleshoot for them.
I can sense the frustration of the installer. He may not be great at electrical issues.

There is always a ground between the engine and chassis. However, if that ground were not there the engine wouldn’t run.

@“the same mountainbike” You are right about this. I still think it shouldn’t be that hard to track down the problem. The AC compressor clutch isn’t getting power. Either the positive voltage is,missing, or the negative isn’t there. A voltmeter or test light can reveal the problem here. If the + voltage is missing, it may be that the switch has opened if the refrigerant is low. Maybe a leak was caused when the engine was replaced. Perhaps a connector to the dash board wasn’t reconnected. If the negative isn’t there, a ground is missing to the AC compressor clutch. If there is power to the AC compressor clutch, the clutch is defective.

I wholeheartedly agree with your list of possibilities.
I also agree with your recommendation of a shop that specializes in automotive electrical systems. I’ll bet they could track the problem down before the OP finishes his cup of coffee in the waiting room.

@“the same mountainbike” What if the electrical shop doesn’t have coffee in the waiting room?
I had a compressor that wouldn’t kick on in a Ford Maverick I owned years ago. The mechanic at the,Sunoco station where I traded pulled the lead off the compressor clutch and tapped it against the positive post on the battery. The clutch was activated so he knew the clutch wasn’t getting power. Since the,Sunoco station wasn’t equipped to do AC work, I went to the Ford dealer. It was determined that the switch on the dashboard was the problem. A new switch was ordered and the mechanic filed the contacts on the old switch and I left with workking AC at no charge. The dealer was supposed to call when tbe, new,switch arrived. I never received a call, but the. AC was still working four years later when I traded the car.

When an engine is replaced, there are wiring harnesses that have to be unplugged and set aside.

Maybe a plug for a pressure switch in the AC system wasn’t plugged back in when the harness was reconnected?

Tester

Same scenario…Yesterday I went to pick up my 2008 Camry from dash replacement and oil consumption fix (rings / Pistons) and now my air isn’t working either. Dealership said air wasn’t working when I brought it in but it was, perfectly in fact.