A/C fan wiring

I was in hopes your question would generate AC info. My cars previous owner reported blowing an AC hose when he first purchased it. He replaced the hose and charged the system per my request before my purchase but was unsure of the tech wiring update. Any insights? JD

I believe the replacement anti-icing switches referenced in the tech service bulletin are no longer available new. I would suggest installing a triad switch available from most AC parts suppliers and for sure from Vintage Air. Wire the contact for the lower of the high pressure switches to send power to the condenser fan relay. This way the fan will run whenever the system pressure reaches the high point. This is how most modern systems are controlled.
Good luck,
Forest

Last year I got my A/C to work for the first time since I bought the car, a new hose (not a blown one, just a leaking one) and charging the system. And it worked fine last summer, no problems.

This winter, while taking the dash apart for other reasons, I damaged the "heat sensing tube" on the A/C switch and had to buy a new one. When I bought it the vendor mentioned that there was another version that had a constant power terminal (when switched on) so that the fan would use that terminal and the compressor wolud use the temperature sensitive terminal. Would that solve it? It would mean that as long as the A/C switch was on, the fan would be on. But if I turn off the A/C, of course the fan would stop regardless of pressure build up.
1. would buying that switch solve it?
2. where is the fan relay placed, what is the colour of the wire I would use?
3. Where is the anti-icing switch placed? If it's not there, will the system still work?

Thanks, we need to stay cool, right?

If you go to the panteraplace website and look at wiring diagrams under technical you will find an early and a late diagram. The late diagram shows the switch you were referencing in the TSB and noted by the vendor but if you have the earlier version then you need to rewire as noted in the TSB. If your AC switch that you replaced has three wires then you already have this function. If only two then you can do one of three things:
1. Buy the newer switch and wire it in as per the TSB (I think this switch may be unavailable at this time)
2. Install a high pressure cut out switch somewhere in line and wire it in series with the compressor clutch to stop the compressor on high pressure or
3. Install a triad switch and wire the blue wires to power up the condenser fan relay when pressure calls for it. The advantage to this switch is you can wire the other pair in series with the compressor relay and shut down the compressor on low or over high pressure, thus preventing running the compressor without refrigerant to carry lubrication.
Most of the fan and compressor relays are inside the cover in front of the driver's door unless it is an early car and then I believe they are in the same area as the fuse block.
Good luck,
Forest