Air Con: $1697 for an on/off switch

Original Article ↗ Hacker News Discussion ↗

Vendor lock‑in and business model

  • Many see the hard “not on AA hardware” lock as unjustified, especially when the tablet is just a generic Android device with a model check.
  • Some argue the restriction might reduce support burden (people installing the app on random tablets), but others say this could be solved with in‑app warnings and better support tooling, not hard blocking.
  • The pricing (≈$1.7k for a low‑end tablet “switch”) is widely viewed as profiteering and de facto planned obsolescence, especially since failures cluster just after warranty.
  • A minority suggests simple cost‑optimization and lack of foresight might explain the design, rather than deliberate malice.

Tablet failures and flash storage

  • Many suspect cheap eMMC plus excessive logging or swap is wearing out storage, a common failure mode in IoT and cars.
  • Discussion covers over‑provisioning, wear‑levelling, and the tradeoff between slightly higher BOM cost vs. shorter real‑world life.
  • Others note that even without wear issues, commodity Android tablets are unlikely to match HVAC lifetimes (10+ years).

Technical reverse‑engineering details

  • The “PoE” board appears to be power + serial (RS422/RS485‑like) over Cat5, not true Ethernet; the tablet sees an FTDI‑type USB device.
  • USB is point‑to‑point; the internal PoE/serial board was bodged onto the same D+/D− lines as the external port, so cutting the data lines to the PoE board avoids bus contention.
  • People are dumping and decompiling the APKs, modifying smali to bypass model checks, and probing the control bus, which carries simple XML‑wrapped CAN messages. Some systems appear unencrypted; others mention AES keys in binaries.

DIY repair, Home Assistant, and alternatives

  • Multiple commenters describe similar hacks for HVAC, mini‑splits, and other appliances: ESP32/ESPHome, Tasmota IR, BACnet, local HTTP APIs, and Home Assistant integrations.
  • There’s active interest in replacing the tablet entirely with open hardware talking RS422/RS485 to the controller, or bridging to standard home automation.
  • Many share stories of cheap component fixes (capacitors, relays, thermal switches) vs. expensive board or system replacements.

Consumer rights and regulation

  • Australians discuss using the Australian Consumer Law’s “acceptable durability” guarantees to push back on expensive out‑of‑warranty failures.
  • Some call for mandatory publication of control protocols, right‑to‑repair laws, and even GPL‑style licensing for home infrastructure software.

Attitudes toward “smart” home infrastructure

  • Strong skepticism toward cloud‑tethered or proprietary “smart” control of critical systems (HVAC, hot water, EV charging).
  • Others note there are good, locally controllable examples (certain AC brands, open APIs), but emphasize choosing hardware that still works in “dumb” mode.