Just installed a Seicane head unit in my track car, mostly to get easy digital gauges. But now the HVAC center control buttons are not functioning. Has anyone had and fixed this problem?

 

Quick poke at their documentation, it appears that the stock Rx-8 head unit is unplugged. The HVAC controls partly route through the stock head unit. If your new unit did not include any directions about reconnecting the HVAC controls, this is most likely why you no longer have working HVAC controls.

Metra/Axxess has been the "best" 3rd party that offers a kit to integrate the built in HVAC and aftermarket headunit.

https://axxessinterfaces.com/products?search=rx-8

Good luck.

 

Thanks for the reply. My post was incomplete about what I've done. The instructions and customer support say to reuse the factory circuit board from the OEM head unit to keep HVAC operational. I have done that, plugging all the factory connections to the circuit board and installing it behind the android unit. I've also installed a separate ground since the ground through the head unit isn't there and verified the 12v power source to the central control cluster is working. I think I'm probably missing one input that was sourced from the head unit that I can't figure out. And reading the service manual wiring diagrams is certainly not something I can do even marginally. Would appreciate any help or suggestions and prefer to try to work it out on this unit before considering an additional purchase.

 

Ah. Got it.
I'll have to agree on the one missing input/connection that completes the circuit. Knowing that the install doc has the radio control board connected. I do know from personal experience, that the factor harness connections do loosen up over time.
The HVAC section does go into depth for troubleshooting the connections. Its just getting to and physically testing to connections really stink in that tight space under the dashboard.