Hey all, a friend called me and said she tried to replace her thermostat today in her home. The old one was a mercury one and the new is electronic. She swears she has everything hooked up correctly,and the power is on. She is getting a no A/C power icon lighting up. So, what are the best diagnostic steps? By the way, it is a heat pump unit. Thanks all!
Coming to you from beautiful Richmond, Va.
Replies
Correct voltage?
PAHS Designer/Builder- Bury it!
You said the magic word -- heat pump. Many electronic units won't work with a heat pump.
Honeywell makes two electronic thermostats for two-stage (auxiliary heat) heat pumps, and they usually aren't available at blister pack depot. Models are CT3611 and CT70. Go to http://content.honeywell.com/yourhome/ to learn more. Google those two models, and you'll find many on-line sources, including Honeywell.
Best diagnostic step is to verify that you have the correct thermostat for your application, then that it's installed per the instruction manual. Double check the wiring at the other end so you know which color wire is on which terminal at the furnace/AC unit.
Sounds to me like she bought the wrong stat. Some are powered from the furnace control board (power stealing) and some are powered directly from an AC power source. A power stealing model is typically used in a residence.
Do you know the make and model of the new t-stat?
Not knowing any more details than were provided, the best diagnosis steps are:
Take the old thermostat to a reputable professional. Have the information handy about the make, model approx age of the equipment connected. Take note of the wires (#, color) connected to it. Have them select the appropriate stat.
Optionally, have the professional come to the home and do the work on the spot.
Edited 6/24/2004 6:29 pm ET by Timbo