A few weeks ago, I swapped out my burned up ECU (P06-A02) with a used one, a P06-A01. Sure, it fixed my main problem and is driveable again, but now my dome light and trunk light do not work and aren't getting any voltage at either.

Today, I replaced my A/C high pressure hose. I went to put R134A in only to realize that my compressor is kicking on, but the fan isn't. This is making it impossible to accurately fill the refrigerant. I know my fan worked just last month and I find it hard to believe that it doesn't have something to do with my ECU swap since other electronic stuff has stopped working since then.

So what gives? I thought the A00, A01, and A02 ECUs were all interchangeable?

 

These^ have NOTHING to do with the ECU and therefore are separate problems. Where did you test for for voltage? Give details if you want help fixing these problems.