I was at tuna sisters house trying to help her with her thermostats. The first problem is that they were honeywell from Amazon warehouse (with no battery backup!) and maybe bad, but beyond that there was a problem I did not understand.
It's a single AC, single air handler, gas furnace with two zones.
The blue wire, heading to the C terminal, measured at 18.6 Vac, The green wire heading to the G terminal, had a little over 26. At the air handler in the attic they both show over 26. There's a box that splits the zones, I did not understand how it worked, but nothing looked amiss.
What could cause the blue wire to have less voltage at the thermostat than it does at the air handler?
Will a drop like that cause an issue with a thermostat?
If so, how was the existing thermostat working? It works now.
Thanks!
