Unit running without thermostat

[toddsranger]

I am working on a unit and installed a honeywell focuspro 5000 thermostat. I have it operating by batteries. I can flip the disconnect on outside, and the unit will run even if the thermostat is switched to off. I have Y and C going to the contactor coil, and it is getting voltage even with the thermostat switched to off. Could the thermostat be bad? All the wiring in the airhandler and the outdoor unit appear to be wired right by the schematic. Thanks!

[ckone180]

By the wiring, it shows the C terminal as optional when choosing not to use batteries, which means the thermostat is using it as a common. I also has a standard 5 minute wait time when the unit is first started. See if this is the case.

[toddsranger]

I do have it wired to run off of unit power as well. Even with the thermostat off, I read 24 volts across the contactor coil

[indianajones]

contacts welded in the t-sta? short in the wiring?

[beenthere]

Reread the wiring diagrams.
or is this why you changed the thermostat in the first place.

[beenthere]

Reread the wiring diagrams.
or is this why you changed the thermostat in the first place.

[toddsranger]

I changed the thermostat becaue it had an 1800's style mercury bulb! It worked fine before I changed the thermostat, atleast that is what I was told.

[indianajones]

don't allways believe what you are told.with the t-stat off do you have 24 volt's at the furnace or a/h going to the cond.

[beenthere]

Since your still in school. I hope your doing this for family, or a friend.

Read the wiring diagram. And then reread the wiring diagram.

[toddsranger]

I have 24 Volts across the contactor outside. That was the only voltage check I did today!

[toddsranger]

I am auctually doing this for a friend. If I can't figure it out, I will just have to put the old t-stat back on.

[beenthere]

Get your meter out, and trace your wires.
At the moment, I vote for a miswired stat.
But friends aren't always honest about how well something worked, when they ask if you'll do something like this.

[toddsranger]

I found out today that the unit outside was not wired right. It is a Lennox outdoor unit and an American Standard air handler. Both were wired by the schematic, but they both used different wire colors, so it was miswired outside. It runs great now, and the t-stat was fine!