Tstat calls for heat, fan comes on and furnaceworks and other times have to reset the tstat before it will come on .have changed the board, gas valve,flame sencor and still having problem. some times the fan while it is in a heat cycle will stop for a split second
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Will the fan run with the fan switch in the ON position? as opposed to the AUTO position. If so the temperature or time delay or motor may be bad. the fan switch operates the fan relay that controls high/cooling speed, heat speed is a time or temp delay.
On older systems the fan is controlled by a time delay relay which will turn of the blower after a preset time when a call for heat is present regardless if there is a burner function or not. Need to check why the main gas valve is not energizing, there are to many configurations for a complete diagnostic without further info, Model, Brand etc.
Electric strips have what's called a Sequencer also called a stack relay it's a relay that brings on the fan and strips at the same time on a call for heat. If you have more than 5kw you will have more than one Sequencer in fact you will have one for every 5kw.(only the first one will bring on the fan) It could be your high limit making your unit stop heating before it reaches the temp set on the T-stat. Check and see if your getting proper air flow across the electric strips your filter could be dirty. If not remove the cover from your T-stat and take the red and white wires off and twist them together this will bring on the heat then just watch the unit for about an hour if no problems then you have a bad T-stat. If the unit does cut off and the fan seems to be blowing fine you might have a bad high limit switch.
Since you have fan operation,via fan on position, your high and low voltages are present. I would take the thernostat face off and jumper red to white for heat, if it works , the tstat is bad, same with red to yellow, if AC outside comes on.
Does your fan work from the on position. New tstat may have RC and RH need to jumper them. If that does not work. Turn on tstat check voltage on board at furnace between w and c if you have voltage you may have a bad board. Also see if there is any reset buttons like on the roll out switches. Smaa red buttons. Push them to reset. Let me know what going on. Rus
sounds like you shorted out the heat anticipator in the tstat. try jumping red to white at the tstat wiring terminal and have a friend stand near the furnace to see if it cranks up immediately. if it does the problem is more than likely in your tstat. be sure to blow out any dust in the workings of your tstat. this is 24 volts and shouldn't hurt you but try not to short it out to the common or other wires.
On a Trane furnace the fan realy must energize before the electric strips will come on. On the thermastat. See if there is setting for electric heat. This will bring the fan on and the strips should come on. First just turn on your heat and and turn fan to on postion if it works you need to set tstat to electric heat mode. Most of the time there is sswitch in the back of the stat that says gas elec. Turn to electric. Rus
Check to make sure you have 24-28 volts between R and C. If you do, you probably have a bad board but you also need to verify that you have the same voltage between W and C on a heat call if not then it could be something in the tstat ot he wires (jumping R and W pretty much rules this out).
The Kill switch may not reset the board, kill the power to the furnace itself.
Was the problem there before the new tstat was installed?
Also on some models continuous blower is initiated by a "kicked" roll out switch or and overtemp condition, Check for continuity on the whole safety circuit.