What year did Honda switch up the A/C components on the eg? I got a 92 SI and the interior parts (those big black boxes) for the a/c that came with the car weren't working, mainly i'd try turning on the heater and it wouldn't come on. (everything was plugged in) anyways so I went and bought some new interior a/c boxes and put those in my car only to find out that the harness for the old pieces was slightly different than the new pieces. (this middle box, i can't remember which one that was, the harness on the old one has a 2 wire plug and the new one has a 3 wire plug) So now I need to find a new harness that works for the new set up, or i guess maybe switch back in that middle box and keep the other two. Cause I'm pretty sure the heater not coming on would be the left box, witch would be the (heater core?). Also I was told the pieces I bought were out of a 95, but i never saw the car so I can't say for sure.

 

The evaporator is the thing it sounds like you're having issues with.
The R12 system used the 2 wire plug, the R134A system used 3 wires. Sometime in 1993 they changed from R12 to R134A.

your simplest option is replacing the sensor deal on the evaporator, the "middle box". The sensor will come off, you don't have to replace the whole assembly.