... you probably won't like it, but here's the bad news. Testing the clutch on the compressor with a jumper wire won't hurt anything, but using a test light to check anything going to, or coming from, the a/c control module, whether in the cab, or under the hood, is a bad idea. On our trucks, the volts going to the sensors, relays, etc. may only be something like 3 or 4 volts (it could be more or less, depending on the component). Meaning, there's not enough current to make the test light to, well, light up. And, if you have a hot wire sending 12 volts back through a system not designed to handle that amount, very bad things happen. In this case, a volt/ohm meter would have been the tool to use. According to my dad, you may have accidentally fried your a/c control module. He said that the a/c system can get pretty... complicated, and even the different manuals for working on the a/c doesn't really tell you how to go about fixing the darn thing, or what all to check.