Your A/C amplifier is dead.
Toyota stopped making them.

You splice at the A9 amplifier plug — the same plug the dead amplifier came out of. Nothing else in the car is modified, and the job is reversible if you ever find an OEM unit.

The safety that matters most never touches the microcontroller. Your A13 dual pressure switch still gates the clutch relay's power feed in hardware — if refrigerant pressure goes high or low, the compressor stops regardless of what any code is doing. On top of that, the board boots with the clutch off and drops the compressor on loss of signal rather than latching it on.

Yes, and this is where most amplifier workarounds fall short. The factory amplifier had three separate fan jobs and this reproduces all of them, including the series/parallel low-high speed switching. The frunk high-pressure switch still forces high speed purely in hardware.

Yes — but not the Swap Edition. On a stock car it would leave factory behaviors missing (the vacuum idle-up ground, the high-RPM compressor cutout, and on an automatic the ECU cut request), and I won't ship something that quietly does less than the part it replaced.

Those are exactly what Unit A and Unit B add. Unit A (-17120, MY1991–92) is in stock. Unit B (-17130, MY1993–95) is a 30-day pre-order while the last three values are measured on a real car.

Ask me before you order. The board's dedicated idle-up signal is the factory B-W wire, which is +12 V while the clutch relay is closed — so a ground-triggered ECU input isn't what this is wired for out of the box, and all three of the board's switched outputs are already spoken for.

There's likely still a clean answer: L-O is pulled to ground at the exact moment the clutch engages, so an ECU input that's looking for a ground may be able to read it directly with no change to the board. Whether that's right for your ECU depends on what it expects to see, which is a conversation worth having before you order rather than after.

For the Swap Edition, yes — the automatic used an extra amplifier terminal running to the ECU, and that path isn't part of this build.

Unit A covers it: the P-G input from a 5S-FE automatic's ECU is one of the three stock-car functions it adds, and its 15-position terminal serves both transmissions from the same board. It isn't built yet — get on the list.

The Swap Edition and Unit A won't — they were worked out against the 17120 and the 1991 wiring diagrams, and later amplifiers differ. A -17130 car is Unit B. A -17100 (right-hand-drive Rev 1) has no product yet. Anything else, send me the part number and what your car does and I'll give you a straight answer rather than a hopeful one.

Two things, both covered in the guide: the voltage divider ratio against a multimeter at the battery, and the two evaporator ADC values while the core cools. Ten minutes with a laptop. On built units I set sane defaults, but every car's sensors drift a little differently.

Built & tested units carry a 1-year replacement warranty on the hardware — if the board fails on its own, I replace it. That can't cover installation, because I can't inspect your splices. Kits and bare PCBs are covered for dead-on-arrival defects; email me and I'll make it right.

No. The complete documentation pack — schematic, wiring guide, component list, firmware, enclosure files, diagnostic checklist, validation reports — comes with every order, including the $25 bare PCB, and is delivered by email after purchase. It isn't published separately. Here's exactly what's in it.