In heat mode but heat strips don't come on and the air handler fan dose not turn off

Turn power off. Put the red from the airhandler to the violet from air handler. Turn power on and tell me what happens.

With some units you must set thermostat to fan on to get the fan to run in heat mode.. or it could be a bad motor or fan relay . Generally in electric heat units one side of heater is always live then the sequencer turns heater on when thermo calls for heat.

The 3 amp fuse is in the red low voltage (24 volt) thermostat wire
and only gets power when the thermostat is set to turn on heat or a/c It should be connected to the red wire from the thermostat

the w wire off thermosta controls heat. eithe bad board or thermostat.

if you have change the thermostat it has to have the option for electric heat the thermostat has o turn the fan on in heat mode on air handlers

burnt wire lead, bad start capacitor or bad fan motor.

The fact is, the air handler supplies the voltage, blower, and electric heat. In order for the heat pump to work correctly, the wiring from the thermostat and heat pump need to be hooked up right to the air handler. The thermostat is what tells which component to come on. If the fan stops, but the condenser keeps going, you either have a faulty fan relay on the air handler, faulty thermostat or wiring, faulty wiring at the heat pump, or the contacts on the new unit are sticking, which is highly doubtful considering it is working now. I hope I have helped you understand this a little more. Good luck and don't let them push you around, get someone that knows what they are looking at.

Generally, you would go from the thermostat to the air handler, and then, from the air handler to the outdoor unit. I don't know if you have a heat pump or not, so I will give you a simple diagram and you can contact me if you need more.

Thermostat : Y G R W and sometimes C
Air handler: Y G R W and C
Outdoor unit: two wires connecting to the contactor ( not heat pump)

Thermostat; Y--------------Y(air handler cooling)------------------one side of contactor, outdoor unit
G-------------G (air handler, fan)
R--------------R (air handler ,hot)
W-------------W (air handler, heat)
C--------------C (air handler, common)------------other side of contactor, outdoor unit

This is a typical wiring diagram. Just contact me if you have something different. Hope this helps. Stay cool. mark

Hi,

This will help you.


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Thank you for using fixya have a nice day:-)

If you have a standard thermostat the fan switch is for the air handler only. It completely over rides the thermostat for most settings. Now lets see this is what I'd expect:
fan switch on Indoor fan runs all time
Fan switch auto Indoor fan only runs when thermostat is set to cool or heat and the thermostat is turned up above room temp for heat or below room temp for cooling. In both of these modes the furnace blower comes on and stays on til the room temperature is satisfied. The outdoor unit only comes on for AC the out door unit will not come on for heat or the "on" setting on the thermostat. See exception 1 & 2 below...

Exception 1- (in a heat pump the out door unit runs in both heat and cool mode unless it has emergency heat turned on then it will not come on outside in the heat mode, and depending on the type of heat pump and furnace or air handler it is). A heat pump thermostat usually has "backup heat" and an "emergency heat" setting switch on the thermostat.
Exception 2 - On some thermostats they are made to cycle on the heat if the temperature reaches a preset temp (around 50'f usually but definitely by 40'f). This mode prevents freezing when if instance the homeowner is away or while the home is under construction. In this mode the fan inside can run but the heat usually comes on with it.
Exception3 - On some electric furnaces the heating strips may be individually controlled and thus not all come on at one time. This may give the feel of no heat especially if the room is cold.

Now there may be other exceptions but Ive tried to give you a heads up on some of the most common ones.
If you need more help please post more specifics about your unit/system as to for sure what switches are set to what setting and what is happening with each. My first though was that maybe your system is OK and you needed to know if the thermostat was working properly.

If this helpd you understand your problem would you please give me as hifgh a mark as you can. Thnaks for using fixya and good luck.