Question about Heating & Cooling
Hi, if indeed it is the transformer and not the batteries in the thermostat, check first, Depending on if your furnace is a split system, or a package unit, the transformer is located just after where you're main or high voltage enters the unit. In a package unit as on the roof, it would be in the main control panel just after the Contactor.On the split system furnace and condenser split up, it is located in the furnace control panel where the 120.volts comes into the furnace. It is normally a square looking silver solid looking box with electrical wiring connects to both sides.The split furnace will have 120 volts going into it, 1-black and 1- white.The other end will have 24 volts coming out. It may have markings such as R, C, G, Y, and W, just like the thermostat. This is the 24volt side supplies voltage to stat and other components. Set meter to above the voltage you want to check.Check to see if you have 120 volts coming in across the black and white. If there is power to the furnace, you will have 120 volts to the transformer. Now check the the other end to see if you have 24 to 28 volts from Red to C. If you do have between 24 to 28 volts a/c coming out, then the transformer is good and you need to look for a small 3 to 5 amp fuse. Newer furnaces will have them plugged into the board. Check to see if it is just the fuse blown. Another thing to check is, some transformers will have a reset on them. If no power out, no reset, transformer is faulty. Most package units will be 220 volts into the transformer, stepped down to 24volts. Check the same way, volts in from main power would be 220 volts or above, and 24 volts coming out from the red wire to the white or black or Red to most other combinations of the stat wires or control wires. Very easy to check. Always look for the reset on the transformer, and a split furnace will be 120 volts in, and 24 out.Nothing out, faulty transformer. A roof top package unit, make sure there is power to the unit first, then check the high voltage in which is called the primary volts. Coming out is called the Low or secondary, 24 volts. I hope this has helped you in finding and checking the control transformer. Very easy to check, and to replace.Just remember, power coming in with nothing coming out 24 volts, no reset, bad transformer. Just follow my steps to the incoming power supply, and you will see the transformer. If you need more help, please contact me, and I will be here for you.Take you're time and it will go smooth for you.Please let me know the out come. Sincerely,
Posted on Dec 11, 2009
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Posted on Jan 02, 2017
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