Then the only thing left is a broken wire/bad connector or a bad out of the box fan. You do know you can test the fan; 12V and ground? You can test the connector with a VOM or test light, when the AC is turned on the fan should be on. You can test the wire continuity from the relay pin 87 to the fan motor. The ground is at the left front of the engine. On some cars there is a diode inline near the fan connector, it is between hot and ground wrapped in tape in the harness.

You might have the codes read, there are a couple related to the fan that may not cause a CEL.

 

The fan wasn't working. He replaced the entire assembly and it's still not working. I doubt that he has had 2 "bad" fan motors.
Most likely going to be a power to fan issue. Outside chance of a bad ground. Just going to have to trace it down.

Add:: Since this is a 2006, I seem to recall that some early productions from that year had a different wiring harness set up than the later made ones.
Maybe Donbrew has a schematic that shows that earlier wiring.

 

The only difference is some 2006 have the diode.

 

Got a call lat night just before the shop closed. They said that they were getting a "resistance" reading from the fan. I told him that the fan was brand new and was installed Sunday PM but that there was a pigtail(could this be the diode you speak of, if so it has been discontinued by GM) between the fan connection and wiring harness that had to be repaired and that may be where he may be picking up the reading. Waiting to hear back for them today. Oh, by the way, I did test the old an new fans with a 12 v battery to see if they would run and they did.

 

I don't see any use for the diode, if that is what is bad. It can be tested for continuity in one direction only. You used to be able to go to Radio Shack and get 10 for $1, they are not special except in the direction they are installed. Later in 2006 it was discontinued with no other changes.

 

Same here. Not seeing the purpose of the diode.
I wonder if you could just eliminate it and connect only the pos/neg wires like the later production.

 

9:45am, still no word from the shop.
So you think just remove the diode and plug the fan directly into the wiring harness?

 

The diode is used to cut out a flyback effect when the relay switches off. Usually the diode is mounted on or near the relay. Any 1N400x diode will work. It will work fine without it.

I would at least test the diode first. Remove the pigtail and test for continuity between the wires, it should have resistance in only one direction.

https://en.wikipedia.org/wiki/Flyback_diode

The more I look at the diagram I am thinking they used a "parts bin" part. That not even the way a snubber is connected; it should be between 85 & 86, many relays have one built-in.