I have a combo roof unit. I have replaced both the capacitors for the compressor and conderser fan, and for the blower motor. The compressor and condenser fan work fine and stay on like they should. However the blower motor turns on and off repeatedly. Sometimes it will stay on for 5-10 min, some times less than a minute but when its on it does blow cold air, and when it turns off the compressor stays on. What could this be? Thanks

Could be a defective blower motor triping on the built in overload.

Way to test is to hook meter to power supply line for the motor. When motor shuts off check meter to see if voltage is still present. If voltage present when motor is not running the motor is defective.

If the voltage is not present when motor stops running you will have to back track the voltage supply to a relay or circuit board to find the real problem.