A/C troubleshooting

I have a 1991 Cherokee that I recently purchased. When I bought it the A/C and heat worked fine. After power washing the engine area the a/c and blower no longer work. The fan clutch does not engage and the blower does not work for heat or cooling. I have checked the fuse and have checked the blower motor, both are OK. Can anyone direct me to a step by step troubleshooting guide for a/c issues? I have a feeling it is a bag switch or relay but do not know where to begin or how to test.

Alan

There's water in something under the hood. I'd start at the compressor, and follow the wiring back to the harness. Open up the connections, check for water and put some dielectric grease in the connections. After each one, try it again to see if it works.