Switches to on (blower) by itself

Check first that

• the air conditioning equipment is turned on,
• the thermostat is calling for cooling, and that
• the blower unit or air handler is actually blowing air through the ductwork.

Here are the details of what to check in what order if your air condtioner or heat pump doesn't start at all when you set the room thermostat to call for cooling:

1. Check the Room Thermostat Temperature Setting: Set the thermostat to at least 5 degrees below room temperature. Our elderly mom has no patience with switches and controls. She regularly calls her air conditioning service company with a service request, sometimes late at night, because she has simply failed to set the temperature on the thermostat lower than the room temperature. Don't drive your A/C like our mother.
2. Check that the Room Thermostat is set to "Cool" not "Off" or "Heat". If the thermostat is not set to "cool" it is simply turning off your A/C. If the thermostat display is blank then it's not receiving power (for modern digital thermostats). Check that electrical power is on at the air handler and to the the low-voltage transformer that supplies power to the thermostat.
   
   If the thermostat has power, check that when you set the thermostat temperature down at least 5 degrees below room temperature the thermostat calls for cooling. If it doesn't then check for broken or shorted thermostat wires anywhere between the wall thermostat and the control board at the air handler.
   
   You can easily eliminate possible thermostat problems as a cause of failure of the air conditioner to start by simply eliminating the thermostat from the picture: disconnect the thermostat wires at the blower unit's control board and instead connect the two thermostat terminals directly together with a jumper wire. If the system starts then the problem is in the thermostat itself or in its wiring.
   
   If the thermostat is working but the compressor condenser unit won't start, you could skip ahead
   to COMPRESSOR / CONDENSER DIAGNOSTICS but I wish you'd double check the remaining steps in this article first because there are some sneaky snafus listed below that might still be the problem.


3. Check that electricity is on for the equipment. Check all of the electrical switches and controls that can turn electrical power off at the indoor air handler or at the outdoor compressor/condenser unit. There are more of these switches than you might guess. Here's a list of what to check:
   
   Electrical power switches and service switches outside by the compressor, inside at the air handler, and fuses or circuit breakers in the electrical panel. Don't forget to check that the access covers to the equipment are properly closed and latched. Otherwise a
   BLOWER DOOR SAFETY SWITCH could be keeping the equipment from running.
   
   There are several other safety switches and controls, both manual and automatic that can leave an air conditioner or heat pump turned "off" such as a blower compartment door interlock safety switch, an electric motor overload or overheat switches, and a condensate tray spillage detector switch.
   
   Some hard-to-find electrical switches on an air conditioner or heat pump could be keeping your air conditioner from starting, such as
   a FLOAT SWITCH on Condensate Tray that could
   be
   causing CONDENSATE PAN SWITCH LOCKOUT - condensate spilling into an overflow pan that uses a sensor switch can be enough to shut down your air conditioner.
   or
   a blower MOTOR OVERLOAD RESET SWITCH could be keeping a fan motor from starting.
   
   A bad or failed starter capacitor could also be leaving your system shut down, failing to start a blower, fan, or compressor motor.
   See CAPACITORS for HARD STARTING MOTORS
   
   Watch out: See A/C - HEAT PUMP CONTROLS & SWITCHES to be sure you have found and checked everymanual or automatic electrical switch on the system.
4. Check the electrical supply voltage. Even if electricity is on, if the supply voltage has fallen too far below the operating voltage range of your air conditioner it's likely that the system will not operate, particlarly, you may note that the compressor motor won't start.
   See VOLTS MEASUREMENT METHODS

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

Is your tstat fan selector in auto?? Does the fan ever shut off?

If you need further help, reach me via phone at https://www.6ya.com/expert/thomas_092728000e6acb79

Do you have t sat fan switch in on position??? If so blower will run continously set it to auto and it will cycle with heat call

Only your blower on the inside will work only blowing the air around the inside of house.You get cold air from outside uni.If you just want it to circulate air then turn it off at thermostat and change the auto mode to fan.

make sure your thermostat is not set run the fan,
is there an auto/on switch on the thermostat subbase?
if so then switch it to the auto position

Check your thermostat to see what your fan switch is set on. There should be two settings - auto and on. If it is set on auto, the fan only comes on when furnace runs. If the switch is set on on, the fan on your furnace is running all the time. Which means when temperature in the house reach what you have set on your thermostat, the furnace kicks off, but the fan keeps running and blows cool air. Some people run their fan all the time, especially if they have allergies, because that's a good way to clean the air.

Check the fan switch on thermostat, set to auto. Check control board for error code. Sounds like an over temp. on the unit, it will blow the fan until the unit is cool or there is a problem with either the hi limit switch or control board failure. If the board fails they default to run the blower continuosly.

you have either a bad thermostat or bad controls in the units unplug the furnace make sure the outside unit shuts off turn off the thermostat plug back in if it all starts with the thermostat off you will need service thanks for the high ratting keeps me helping for free.Tom