Is $25,000 to replace the entire HVAC system a fair price?

I bought the house a few years ago. While checking the crawl space, I found a CleanEffects house filter with no LEDs on. I took pictures and researched it, checking the basics like power, ground, and signal. All were present, but from the installation diagram, it appeared the blue and red wires, and then the white and green wires, were flipped at the plug. I called an HVAC company, and the technician took less than 10 minutes and recommended a $25,000 system. I contacted Trane, and they recommended the same company I had called, so I feel I'm on my own here. I changed the wiring to match the diagram. When I plug it in, the 3.2 Amp fuse blows. I'm wondering if the diagram might be wrong.