Installing new furnace with two zones

Transformers typically supply 24v to the circut board, controls, and safety switches. 120v supplies the fan motor. limit switch is a safety switch and is part of the startup/ignition sequence. If the limit switch is tripped then there is a problem with your furnace that should be managed by a qualified professional in your area, or risk damaging your furnace, and perhaps causing a fire. Hope this clears things up.

I need to know what the furnace is doing .
Since you said furnace that's means force hot air and you have 2 Zone damper that's runs on 1 furnace ,correct?
If it's 1 furnace with 2 Zone is Zone 1 working

You have a bad transformer. It may be the capacitor, but i,m thinking the transformer.

These are both power open and closed. Yellow and green should be constant on the leds. C&D is your 24 volts for the controls. If you got power going in but nothing coming out of the board it is bad. If you got 24 going to the damper but damper not responding obviously it's bad. Usually communication is DC voltage, likely 12 or 13 DC at A&B. Good Luck!!

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When I worked Electrical in a Hardware store we were told by Nighthawk and f\First Alert and we told our customers that you want the detectors 4-6 feet off the floor never near a water heater or furnace since this can cause false alarms. The CO will rise, so one on each floor should be enough near a central stair if possible. Other wise make sure at least one is in the bedroom.

You need to find out if the problem is in the T-stat, T-stat wire or in the furnace you can do this in a few easy steps

 

Step 1- Unwire the low voltage from the furnace. Then turn the power back on and see if the blower comes on if it does then the problem is in the furnace and you will need to troubleshoot the furnace (see bottom of page for troubleshooting furnace) if it does not then proceed to step 2

 

Step 2- Wire the low voltage back up to the furnace (follow the wiring diagram below). And unwire the T-stat, make sure that no wires are touching each other, then turn the power back on to the furnace, if the blower starts then you have a short in the T-stat wire and you will need to pull a new wire. If it does not then proceed to step 3

 

Step 3- Turn the power back off at the furnace and wire the T-stat back up (follow the wiring diagram below). Turn the T-stat to auto heat 90 if the heat does not start but the blower just runs then you need to replace the T-stat.

 

 

troubleshooting furnace

 

http://www.hvac-for-beginners.com/furnace-troubleshooting.html

 

 

wiring diagram

 

 

 

 

The stat that works is called the main and the other two are called slave stats. The stats must be set to heat or cool the same as the main. If you want one room to cool and one to heat , sorry. Need to upgrade to auto changeover. Is this AC actally a Heat pump?

Some times field wiring will be of different colors. Green is always for ground. White or gray is neutral and almost any other color can be hot. This is only for higher voltage. The furnace is supplied mainly with 110 volts and transformed to 24 for the t-stat and 24volts runs to the a/c contacts.

double check your wiring. R terminal on the furnace will provide 24 volts to the t-stat. W terminal in the t-stat will send 24 volts back to the furnace W terminal to turn on the heat. G terminal in the t-stat will send power to the G terminal in the furnace when the t-stat is switched to fan on. Y terminal in the t-stat will send power to the Y terminal in the furnace which in turn will send 24 volts to the A/C outside. The C terminal in the furnace should be connected to the c terminal in the A/C outside as well as to the T-stat. Check the fuse again

Not really unless it is 24v control on the new stuff. However it is you can use the voltage from white (or W) at the tstat. You will be using the power supply of the carrier furnace. install a 3 amp fuse. and be prepare to replace the fuse in furnace while testing . The most you can get on those transformers is about 10 mpers @ 24v.