Thermastat is on, fan is running, but outdoor unit is not coming on

If the outdoor unit is running the indoor fan should definitely be running. Turn power off to indoor unit. Put red green and yellow wires together behind the tstat with a wire nut. That is power (red), indoor fan (green), and compressor (yellow.) Turn power back on. This is bypassing the tstat and you should have indoor fan and outside running as well. If yes the problem is in the tstat, if no indoor fan the problem is in the unit. Good Luck!! Let me know!!

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Verify contactor is pulling in. Then verify 240 on load side. Does fan run on load side? Check capacitor...replace cu board

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I'm not sure if the thermostat is wired correctly. First, the thermostat is wired directly to the outdoor unit (compressor/condenser unit). It is NOT directly connected to the indoor unit. It connects to a low voltage control panel in the outdoor unit that sends a signal to your indoor fan/evaporator. This wire is called the fan relay switch and physically runs between the low voltage controls of the indoor and outdoor units. If the fan relay is bad it's possible that the unit runs continuously. To prevent destroying your outdoor unit there is a safety feature that prevents the indoor fan from shutting down while the outdoor unit is running. If the indoor fan did shut down while the outdoor unit was running than you would slug your compressor. That is, your compressor normally sees refrigerant gas but is instead seeing refrigerant liquid. That would not be good since this scenario would destroy your compressor. It sounds like a faulty fan relay. The actual contactor portion of the relay is in the outdoor unit.

I assume you are referring to the indoor fan coming on. If the fan on the outdoor unit is coming on, and the compressor is not, you have a control problem with the outdoor unit, I recommend calling a service man. Make sure you have power to the outdoor unit. There should be a service disconnect on the outdoor unit, connect and disconnect the power, you should hear a hum when the power comes on, put your ear to the housing of the outdoor unit and you will hear the power come on when it is turned on. If no power, or hum, check your breakers in the house electrical panel, see if any are tripped. Next step call a service tech.

HI Daniel, The fan operation is controlled by a temperature sensor which is preset to operate a relay. The relay is usually a normally closed relay which when the cable is removed from the sender unit closes the relay and brings the fan into operation. Check the sender unit, the connection and the relay for defective operation. Regards John

Several problems with these units, (I just finished rebuilding mine). sounds like the fan
relay has failed. This may be due to water dripping on it. Also the sequencers that
were supplied often popped apart( the new ones are clipped together with metal bands)
I would replace both as I have already done.
The outdoor condenser sounds like it is stuck, which is a reversing valve problem.
If the lineset is cool but not really cold, then this is the problem.
luckily the parts are inexpensive for the air handler but the outdoor unit problem
is expensive to repair and I just replaced it as a unit, The good news is that it dropped
the electric bill 84 dollars the first month in february heat mode.
If you can install a new system, I would recommend a Goodman 13 seer minimum. They
are efficient, quiet and less expensive, if your unit is 13 seer on the indoor
air handler it can be
fitted up with a new outdoor condenser. Hope this is useful.

Hello BWOOD Check the thermostat FAN button is in AUTO position not ON position.That might be it .The relay is in the blower unit but they RARELY become frozen/welded stuck on.

High, sounds like the time delay relay went out when you shut it off at the stat, and has failed. It is a small 24 volt circuit board or small black timer box that is adjustable and if it fails will keep the outdoor unit from ever coming on. If you know what terminals to jump across, it can be bypass completely. If it fails which happens many times as I carry many different types for the people who want a new one, it keeps the outdoor unit from starting at all. When it is working, it prevents the unit from short cycling.
Shastalaker7

the indoor usually on contentiously only the outdoor unit On and off to control the temp.

On the outdoor unit the fan should not be running, on the indoor unit the fan should be running. If you then check the outdoor unit with fan not running, you should be able to hear clearly that the compressor is actually working. If this is all correct, it is possible that your fourway reverse valve is seeping and needs to be replaced.