Hello, I am trying to connect a Nest thermostat to a Trane combined heating / AC unit (specifically a Trane HWK01 unit). The existing Trane thermostat controls both the heating and A/C (as well as the fan, for that matter), but only has two (unlabeled) wires. The two wires are red and white, which I connecting to the Rh and W1 terminals of the Nest respectively. This seemed to work ok, but it appears that the Nest thermostat can only control the heating and *not* the A/C. Before proceeding further, I wanted to ask if anyone has any suggestions. I would have thought the Trane unit would have separate wires for heating and A/C, but this does not seem to be the case. I have been unable to find information on a combined heating and A/C unit being controlled by just two thermostat wires, so am confused. Any advice appreciated. Thank you in advance. AJ P.S. Attachments show Trane thermostat, with the two wires inside, and the Nest terminals.

I have a commercial building with 2 a/c units and 2 thermostats. This year we just had both a/c units changed and put 2 new thermostats in (Honeywell RTH2410b1001). The a/c works great but they will not shut off. I set them at 75/auto and both will keep running even when it gets to 70. The fan and A/C system are both running. Any insight appreciated.