Re: outside carrier unit doesn't come on when thermestat...
The board is bad, what you can do is splice into the common (blue) and Yellow t-stat wires and connect them directly into the contactor and hopefully the reversing valve engages, giving you cooling for the time being
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There can be multiple problems with your situation, one being a stuck condenser fan motor contactor/relay, a shorted motor, bad control board, etc. If you could at least check the contactor that controls the CFM and see if it is pulled in that could help narrow down the search for the answer.
Sounds like the contactor in the condensing unit is stuck. That is why it will not turn off when the thermostat is satisfied. If the inside air handler is not blowing and the outside condensing unit is running, then this will cause the inside coils to freeze up rather quickly.
The contactor is located in the outside condensing uni in the electrical compartment.
If it is sticking it will need to be replaced.
Is the furnace fan (indoor fan ) running. If not the problem is with the inside unit. It supplies the control power to operate the entire system and has a control fuse on the circuit board. If it is running but not the outside unit then the problem is outside.
Sounds like you might have a low voltage short possibly at contactor at outside unit (Condenser).
What happens is if your contactor has a short it will pop a 3 or 5 amp fuse at the furnace circuit board. This fuse will continue to pop until the short is fixed the best way I have found is to take off all low voltage wiring at furnace circuit board put them back one by one first with R then W then G then Y if it pops at Y your contactor has to be replaced.
Open the control box and see if you have around 220-240V at the bottom of the contactor. The contactor is the switch looking thing in the bottom. If the unit is calling for air it should have a button in the middle that is pulled in. If you are not getting the volts at the contactor then you need to find the electrical problem. If you have the correct voltage then look and see if the contactor is connected. The middle button should be pulled in. If you have one where you are unable to see the button, or it is not pulled in, Check the low voltage wiring. This is done by checking to see if there are 24V-28V on the side terminals of the contatcor. These terminals are located on the sides of the contactor. (some contactors have both sides of the 24V on one side.) Either way you should read 24-28V when checking across the two terminals. If you do not then you have a problem with the control wiring. (cut with weed eater, chewed by mouse etc.) I know the 24V coil is good because the inside unit is running. If the contactor is pulled in and the outdoor unit still does not run check and see if there is power at the other end of the contactor. (The end the switch breaks off) If the switch is pulled in (or you read 24- 28V on the side of the contactor, and there is 240 V coming in on the line. Chances are you need to replace the contactor. Disconnect the power and pull one wire at a time of of the old contactor and install it on the new. After all of the wires are on the new one, remove the old contactor and throw it away. Screw the new contactor with all of the wires back onto the unit. restore power. Often times in our part of the country, there will be ants stuck in the points of the contactor. Just cleaning the contactor will buy more time. Hope this helps.
Remove the cover on the outside unit that covers the circuit board and contactor and capacitor. Then start the unit and set the thermostat so that the unit cuts off. Then go back to the outside unit and see if the contactor is still pulled in and the unit is running. Next open the breaker and see if the contactor drops out. If it doesn't your contactor could be stuck. Try to free it or replace it. If not the problem could be in the circuit board.
You have an electrical problem. It is either a lack of 220 volts getting to the outside half of the a/c or the 24 volt circuit not activating the contactor (big relay) that carries 220 to the compressor.
Have you eliminated the possibility of a high or low pressure error. Sounds to me like it's off on safety. Should have troubleshooting the flash right on the panel. Test your pressure switches for continuity.
A burned or pitted contactor will/can cause a unit to not run. Outside fan. Just thinking out loud. Start with low voltage check at t.stat then check outside low volt. Set t.stat to on. If fan engages at least your transformer is good. Next set calling for cool. Drop t.stat 68-70. If nothing happens go outside and with a screwdriver depress the contactor in. If fan and compressor kicks in change the contactor. If contactor is pulled in check outside fan. Remove the wires from the compressor and see if the fan will run . If it does you have eliminated start components as good. The compressor has to be check. It needs to be ohmed out. Turn off power at disconnect. Pull the cover on the compressor. Check between pins; then pins to ground. Open or infinite is good.Have you checked fuses. Like small 3-5 amp fuses