Thanks for the year of manufacture correction. That does make a difference.
However, there’s no gold filaments in the Toyota heating system, the AC system, the ductwork, or the controls. There MAY be gold-plated contacts in the fan switch, but even that would surprise me. Contact resistance isn’t critical enough in that system to justify the expense.
What does this mean? Where did you get the $700 quote and what is it allegedly for?
I have an in-depth knowledge of soldering processes, including gold-ball bonding in microwave integrated circuitry, wave soldering, surface mount soldering, soldering of turret terminals, PC board “lands”, and countless other types to NASA standards, DOD standards, and IPC-610 standards, and I have no idea what “fine soldering” means.
PostScript: Aha! your new post, posted while I was writing, answers a lot of my questions. That article makes sense. I noticed that it was posted by a “dot-com” (commercial) poster. Perhaps you could follow that .com lead and get a description definitive enough to do the work yourself. Or perhaps the .com will repair the control unit for a fee far cheaper than what Toyota would charge to replace it (you’d probably have to remove, ship, and reinstall it yourself).