Have a problem with my furnace, and I hope you can help me.
I switch the tstat to call for heat, and the following is what I get .....
1. The Combustion blower starts.
2. Then I hear a '' CLICK ''
3. There is a long quite moment.
4. The another '' CLICK. ''
5 Finally the main blower turns on, and all we have is cold blowing air. NO HEAT.
I never see the Igniters glow, and I only smell a hint of gas.
MAKE : LENNOX
Sounds like the ignitor is bad. there shoule be a 2 wire plug going to it. after the inducer motor starts, you can check the voltage at the 2 wire plug located under the burners. you can unpug it to check voltage or you can probe the back side of the plug with a volt meter. if you are getting 120v but it is not glowing, it is bad. you can also ohm it out while it is off.
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Wiring to tstat and board. Without knowing unit or tstat most common is red-r, white-w1, yellow-y1, green-g, and blue or black-c. This is if you dont have a heat pump. Putting a jumper wire on r and w1 should bring on heat. Jumper on r and g should bring on blower. Jumper on r, g and w1 will bring on heat and blower
Either your fan Tstat setting is set to "on" instead of "auto" or your furnace is going off on a limit switch when this happens it automatically runs your fan for safety reasons. Check your Tstat setting then check and change your furnace filter if neither solutions work time to call a pro.
If its a high or mid efficiency furnace most of the time the sequence of operation goes as follows: tstat calls for heat (R&W at tstat ) ventor motor starts, pressure switch closes, spark or hsi lights pilot or main burners. main blower motor comes on. From your description of a humming noise it sounds like maybe the ventor motor is seized.
Sounds like a bad tstat. The Tstat does control the on and off of the unit.
You can check the Tstat by taking off the white wire to the tstat and turning the heat to the on position and if it still comes on you have a bad wire. If it does not come on then you have a bad tstat.
Another option is to open the furnace and look inside at the control wires and follow them back to ensure that they are not shorted together anywhere inside the unit before checking the tstat wires.
If its the control wires then follow option 1 if not follow option 2.
1.Normally people who run tstat wire pull more wires than necessary to the tstat. Because of this you can use a different one for the heat which is white on the tstat. Remember that if you use another color on this then you need to change it on the inside unit as well. Otherwise it will not work. In other words change it on one end of the line you have to change it on the other to make it work.
To check the tstat wires, use continuity. Take all the wires off the tstat and the inside unit. These are the small control wires, not the main 110 wires. Check each one against each other to see if any of them are shorted together. Be sure to write down the wire colors and the terminals that they belong to on both sides before you take them off otherwise you will have big problems...
If you do not have another wire then pulling a new wire will be the next option.
2. If this does not solve it, then its the TSTAT, Replace it.
Hope this helps.
MOST UNITS NOT HEAT PUMPS WIRE UP WITH 2 WIRES TO CONDENSER RED WIRE AND WHITE . WHITE GOES TO COMMON C ON FURNACE AND RED TO Y TERMINAL OF FURNACE Y ALSO GOES TO Y ON TSTAT. BOTH YELLOW WIRES MUST MEET AT Y OF FURNACE. WHITE FROM STAT TO W GREEN FROM TSTAT TO G AT FURNACE IF YOU HAVE C ON TSTAT HOOK UP BROWN WIRE OR BLUE FROM COMMON TERMINAL WHERE YOU HOOKED UP CONDENSER WHITE WIRE AT FURNACE TO TSTAT , MOST THERMOSTATS DONT NEED C RUN FROM FURNACE. THE TWO WIRES GOING TO CONDENSER IS - AND + TO ACTAVATE CONTACTOR IN OUTSIDE UNIT
the tstat sounds like it is not connecting the white and red terminals which is usually the heat cycle if it is a gas furnace if so to check I take tstat cover off and jump white terminal to red terminal this is the standard heat position the unit should fire the heat cycle if not a gas funace let me know what type of unit you have hope this helps
If your running gas heat it's 5/8 3/8 tubing.If it's elec. heat it's 3/4 3/8 tubing. Etheirway 3/4 3/8 works for both. Use 6 wire for tstat from tstat to furnace or air handler, and you need is 2 wire from condensing unit [outside] to furnace or air handler or anything more than two.