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The power to the thermostat comes from the transformer in the furnace or air handler whichever you have. 1) the power to the furnace/AH is off, 2) the control fuse that protects the transformer is blown, 3) the transformer is defective, 4) the wire between the furnace and the thermostat got cut.
What else can I help you with?
Why is the heat and air system only working on emergency heat?
when running the heat-pump the air blowing from the heat ducts is not hot ( it's to cold for the heat-pump). you have a main furnace and it won't turn on ( is thermostat selected for this source), ( is the power switch for main furnace on ), ( is fuse for this furnace good). If these are good (check thermostat wiring at thermostat, and transformer).
Why is your heat blowing out cold air?
Replace Thermostat
What to do when it wont switch from heat to air?
Try replacing your thermostat.
Ac works but no heat blows cold air?
Bad Thermostat
Does the thermostat keep the air cold on cars?
A thermostat, as used in a motor vehicle, is essentially a heat actuated valve which, when open, allows coolant to cycle through the cooling system. The coolant absorbs heat from the engine and cycles it to the radiator, where the heat is exchanged to the ambient air which flows through the radiator fins. Air conditioning actually works in a similar manner, but is not affected by the thermostat - the thermostat does, however, allow you to have heat in your vehicle.
Why does the thermostat turn on the fan but not the heat?
The thermostat turns on the fan to circulate air in the room, but it may not turn on the heat because the temperature setting has not been reached yet.
What causes heat pump system switch to backup heat?
An ouside air temp changeover thermostat. lc
Can a bad thermostat cause the heat to blow cold air?
Yes, a faulty thermostat can cause the heating system to blow cold air. If the thermostat is not functioning properly, it may not signal the furnace to turn on and produce warm air. It's important to have a professional inspect and replace the thermostat if needed to ensure proper heating.
Can a heat pump thermostat be used on non heat pump air conditioning system?
yes it can but everytime you want heat you have to put it on Emergency Heat..
What is the meaning of air-preheater in thermal power plant?
A thermal power plant is more efficient when energy can be captured for reuse. Air coming into the combustion are ignites the fuel more efficiently when it is hot. Air leaving the combustion area looses some of its heat to the steam system, but a significant portion of the energy is lost with the exhaust gases. The preheater takes these two energy conditions (one area needing heat and one having "lost" heat) and combines them in a heat exchanger (preheater) where the heat from the exhaust gases is used to warm the incoming combustion air.
Were does a thermostat gets its power from on a central air conditioner?
The furnace or air handling unit in the house.
The engine is overheating and you have no heat just cold air blowing?
Probably a bad thermostat.
