Carrier 38CKC front on unit

you need to take the temp of whats coming out of the plenum and the temp at the return and subtract them and you should have a difference of 17-20 degrees, that will tell if you are cooling properly,

Air conditioner compressor will not start. When power is applied to the air conditioning outdoor unit the fan starts, but you hear a sound like the compressor is trying to start, "UGGG"..., for about 5 to 10 seconds and then all you hear is the outdoor condenser fan run. The compressor is locked and will not start. What is happening is the compressor is trying to start, but because the compressor motor is locked it tries to start for a few seconds and then because of the high amperage being drawn goes off on internal overload. The internal overload protects the compressor windings from overheating and burning up. I see this many times during the start of the air conditioning season. Some compressors just have a hard time starting after sitting all winter long. Some compressors are locked up so bad that I can not start them and must tell my customer that they need a new compressor . Many times I can get the compressor started again without having to buy a new compressor by using the device called, "Super-Boost." I keep two or three of these on the truck. They have saved many of my customers from having to buy new compressor

here ya go
www.xpedio.carrier.com/idc/groups/public/documents/.../38ckc-c2w.pdf

does just the fan motor shut down and you can hear the compressor still running when this happens?
did you replace the running capacitor for the new motor? is the motor a compatable replacement? how many amps is the motor drawing?amps should be close or under nameplate rating? is the outdoor coil clean?did you reinstall the fan blade the same depth as the old one?do you have the proper voltage to the motor?

There's no polarity, it's AC voltage.

Here ya go:
http://www.xpedio.carrier.com/idc/groups/public/documents/techlit/38ckc-c2w.pdf

Ensure the air filter and evaporator coils are clean. If they are clean and everything is running properly, then the unit may need refrigerant. It depends on the age of your equipment and the location of the leak (price to repair) as to whether or not the unit is shot. Check your air filter and evaporator coil first. :-)

your indoor unit is only circulating the air in the house. for your condensing unit. check your breaker in the electric panel. your contactor or your capacitor.

The start capacitor may be the problem. Is your AC a central unit or window unit? Whats the model and make? If a window unit it could also be the thermostat is defective or too close to evaporator fins. Dirt on the condenser outside can cause the motor to heat up to the point it shuts down to cool the internal overload. Let me Know, Sea Breeze

I am assuming that you are talking about a central ac unit. On a central air unit the outside fan must be running whenever the compressor is. If it's not the compressor will shut off from overheating withing minutes. First you need to shut off the unit for several hours and let it cool completely down. Then turn it on briefly to see if the compressor starts and see if the fan tries to start.( I am assuming the compressor starts and runs.) If the fan won't start try testing the capacitors. There are usually two one for the fan one for the compressor. Sometimes there will be one combo one. Mark the wires and remove the capacitor. Get it tested and if bad replace it. This will probably do the job. If not test for current at the fan motor. Also test to see if it turns freely. The motor may need to be replaced. This will run about $50. The capacitor should always be replaced when the motor is changed anyway.