BLOWER FAN WONT SHUT OFF WHEN THERMOSTATE IS OFF

Is your indoor fan running also? If not, your condenser contactor has welded shut and needs to be replaced

Could be a bad blower motor resistor,mounted by the blower.

Multiple problems. Eliminate thermostat first. Remove face from wall and turn on breaker. If fan still runs you have a bad board or bad relay. If fan outside is running compressor should be too. These operate on same contactor. Verify you are getting 24 volts to coil side of contactor. If odf stops working and contactor remains pulled in you have a bad motor. If odf motor stops working the compressor will shut off due to overheating.

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Try the fan in the ON position on the thermostat, do you mean the fire shuts off or the blower?

If you are saying the unit outside does NOT shut off with the thermostat, you need to check the contactor on the outdoor unit. The contactor may be pitted and stuck shut, not turning the unit outside off when the thermostat shuts off.

The contactor is located in the outdoor unit, the power coming into the unit is connected to it. It looks like a small 3" box and has contacts in it that shut and open with the thermostat. The contacts may be pitted or shorted and you may need to get another contactor. You should be able to see the contacts, you may have to take off a small cover on top of the contactor to see them.
If you take the contactor off, take a picture with your phone first and make a diagram of the wires so you will know where everything goes when you wire the new one in. Hope this helps. Feel free to contact me if you need more help. Mark

If this is a forced air split system, you can try a couple of things.

1) Turn off furnace open blower compartment door and remove thermostat wires. put a jumper between
R and Y. Put blower door back on and restore power.
If unit turns on, your problem is with the thermostat
or thermostat wire.

2) At the outdoor unit remove the electrical panel to
get to the contactor, push in the contactor and if the unit runs you need to check for 24v between R and C
at the control board where the thermostat wires are.
If you dont have 24volts you have a transformer problem.

This is a condenser fan and as long as the A/c unit is in cool mode, this fan will run. The only time it should shut off is when temperature setting is satified and the unit shuts off.

Does the indoor blower come on? If not you might have a low voltage problem in your thermostat circuit or blown breaker or fuse for your furnace which energizes the contactor outdoors. If indoor blower runs check if their are any fuses in your outdoor disconnect.

hi! there,
blower auto shutting off and on is dependent to thermostat setting,if the thermostat acquired the temperature set it will shut of your blower,checking thermostat performance switch off unit, set this to a lower setting 1 or 0 switch on this should not runof course,if you set up this to 200 this will run until temperature reached to 200 it will stop.when you set up to 1 or 0 and the blower run thermostat is defective.
fan blower relay, if the 3 contactor is short or permanently engage while themostat reached acquired temperature your blower will still running,defenitely relay is defective.relay is dependent to thermostat switching,it supply holding coil terminal is to lock the 3 contactor to supply source to your blower.
so two common option while your blower run continously
1. shut off breaker, disconnect thermostat on two leads,its like a switch.then switch on breaker and run unit.
observe if run, your relay is defective,it was shorted on 3 contactor.
thermostat is the key to run your blower.
2. if the blower not run when you switchn onunit,then switch off again and try to short or connect the two lead using alligator clip on both side,or have it clip the terminals,then switch on again if the blower run,your themostat is defective,the high volatile of filler bulb was leak it always switch on,no play at all to off and on.
have a nice day,don't forget to rate me,thank's
ideas came from actual and theoritical analysis base on experienced and my study of industrial intrumentation.this will guide you and help you,if you understant flow of current in circuit.
have a nice day

Your blower fan turning on and off shows your thermostat is working. I am willing to bet you have the fan in the automatic condition. Check for a sticking contactor at the outside unit.