I had and older (20 yr) Adler Barbour unit on board that failed. The older compressors have 4 pins for connection, the newer ones have three pins. This website has good troubleshooting info ( Old Adler Barbour Trouble ) but I contacted him and he doesn't have any more 4-pin controllers. There is a site in England? Frigo? that has replacement 4-pin controllers (approx $250 plug export and shipping) US controllers are much more. In the end, it was my decision to replace the compressor and controller. I didn't want to spend $250-300 only to find that my compressor was aging and need to replace the compressor and the module in a few years. I bought a compressor, dryer, and dual voltage module on-line. Had someone silver braze them in place. As was mentioned above, the R134A is readily available at auto parts stores. Gauges for fill- $25 on E bay, Dual voltage controller (12VDC and 120 VAC) $235 on E bay, Dryer $10 on E bay or Amazon, Compressor- $223 on Amazon. So none of this works if you have a gross system leak. If you hire a refer tech for an initial vacuum check, brazing and final vacuum and fill, you should be way ahead cost wise.