Furnace stopped blowing cold. 'Stat works, blower works. Went outside, condensing unit fan does not run, motor is excessively hot to the touch. Fan blades spin freely. I pulled the disconnect and switched the stat to fan on / no cooling for now but it's 94 degrees today... HELP! :-)

you need to replace your condensing fan motor. the noise you are hearing is the compressor working against a lot of pressure because the heat is building up in you condensing unit. Prolonged operation without an operating condensing fan motor will cause your compressor to burn up, and then you will have the cost of a compressor changeout to the cost of a condensing fan motor.

You have a high temp safety open. The control board sends a signal through all safeties first. And if there is a safety open, the board believes the unit is overheating, so it engages the blower to cool it down. The safeties are normally on the blower assembly, near the burners, and near the heat exchanger. Hope this helps!

This is usually a bad capacitor or bad fan motor. The capacitor is located inside the electrical panel on the outside unit. You can check these by using a meter that measures Mfds (Microfarads), most of the time you can visually see the capacitor swollen or blown. The fan motor can be checked by a meter that measures ohms, really high ohms are usually bad. If you can't spin the fan blade easily, then it's locked up. What usually happens, the capacitor or motor windings go bad, doesn't spin the fan blade, overheats the compressor so it kicks out on thermal protection till it cools back down, and sometimes the motor will overheat and go into thermal protection also. Just make sure you are getting the 220v to the outside unit too, but shut all power off before doing any trouble-shooting. Hope this helps, feel free to ask any questions!

You have a short circuit, which is obviously dangerous. Your blower motor is controlled via a 24VAC control circuit, but is 120VAC. The circuit board and gas valve are probably history, but it needs to be troubleshot to determine the scope of the damage.If you remove T stat you will see several colored wires. The red and green wire when touched together should cause your fan blower to run. If that works when you bypass t stat the t stat is gone. The red to white will open your gas valve on your heater. The red to the yellow or blue will start your AC compressor or condenser fan motor. Be careful with the yellow and blue wires as one is actually a neutral and one goes to the AC contractor on your condenser unit contractor. Hope this helps!

Due to the many different questions I see about Air Conditioning, I am including this overview to help us better understand each other for trouble shooting. A basic air conditioning system has a Thermostat, Air Handler or Furnace Fan and a Condensing unit. In a split system, the condensing unit (Condenser) is separate from the furnace and usually in the back yard. When working properly, it blows hot air. It connects to the cooling part of the system by 2 copper lines. One large line and 1 small line. The part that cools the house is the "Evaporator" and is usually on top of the furnace inside the square metal box (Plenum). When the Air Conditioner is running, the large copper line should be cold and the smaller line should be warm. Common signs of low refrigerant are that both lines are the same temperature and/or frost or ice has built up on the large line at the condenser. The thermostat will normally display room temperature on till it is touched to change the setting. It could have a "Span" setting as well as times and temperatures. The operating "span" of MOST residential thermostats is 40 to 90 degrees. That means you can set it as low as 40 degrees and no higher than 90 degrees. It probably has a fan switch also. When in the "ON" position, the fan will run constantly, 24 / 7, but the condenser will still cycle on and off as needed to keep the house at set point. If you have a suggestion to include in this paragraph, please let me know.

I think I have it covered above. Let me know if you need something more specific. Thank you. Roger

either bad blower motor, or capacitor for blower motor is bad or thermostat not telling blower to come on try to take the wires off t-stat be carefull which one you touch it is low voltage but you dont want to blow a transformer. use as wire and touch the g and r terminals and see if it comes on if it does it is your t-stat if not issue is at furnace or airhandler

check capicitor on motor, fan motor bearings may be locking up when they get hot then when cooled the motor comes back on. Then you must replace fan motor.

if the ac outside is working, but not the furnace, means there is a control problem with the furnace, check wires in the furnace, make sure there is a blower wire plugged into the contact marked cool on the control panel of the furnace

Is the condenser fan (outside) turning? You mention that it's hot but don't say if it's turning or not.

These fan motors normally run pretty hot, but not so much that they shut down due to internal thermal overload protectors.

Both the compressor and the fan have termperature overload protectors to keep them from burning out the motor in the event of an overheated condition. The condenser fan must be running or high freon pressure will put an excessive load on the compressor and it will 'kick out' the high-temp overload protector.

Turn off the unit by pulling the outside disconnect (in a small box near the outside compressor unit) or flip the AC breakers in the breaker box. Wait about 30 minutes for the unit to cool off and turn it back on. If the compressor and fan both run for awhile then kick back off, or the fan motor seems to be working under excessive strain, you've probably got a bad motor start condenser (inside the unit) that little round can that is connected through the fan motor wiring. If it's swollen or leaking, it's almost surely defective and even if it's not, excessive load on the motor is a classic sign of a bad start condenser.

You can usually find these at electrical supply stores, well-stocked hardware stores, or most certainly at an HVAC parts house. Be sure to replace the old one with one of the EXACT same value (in voltage and Microfarads (mF) capacity. The shape may be a little different, but as long as the electrical characteristics are the same and is rated at the same or higher voltage than the original, it will work.

Connect the new condenser, mount it to the frame, and restart the unit. This should take care of the problem.

Hope this helps.

It is possible that you did not set the new blower on the proper speed. Black wire is high. Blue is medium. Red is low. If the fan is operating to slow it can run to hot and trip the high limit control. Make sure the filters are clean. When the old motor went bad, the problem might not have been discovered rite away your high limit control might need to be changed.
Also anytime you work on a furnace you can kick up some dust. Always clean the flame sensor.
Good Luck
HVAC Teacher