It blows cold air for 5 min. and the it blows cool air for 15 min. the room warms up . Why does it stops blowing cold air continuasly???? The thermostat was disconectet on purpose so it coul clow cold air but after 5 min it stops>

See if you can reposition the thermister on the facing of the evaporator coils. That could be it or the thermister might be bad. They don't use copper/mercury sensing bulbs these days. They use these cheap thermisters.

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Sounds like the condenser is tripping and overload and resets when unit cools off after 15 min. Causes can be stopped up condenser coil, too much freon, compressor over amping from bad bearings or a bad capacitor. The contactor could be pitted and not providing sufficient voltage. The condenser fan capacitor may be weak and causing fan to shut off. Fan could have bad bearings and overheats after running causing unit to overheat which Makes real high pressures causing compressor to overamp n over heat tripping the safety overload in compressor. A good start would be make sure the fan outside is up to speed and wash the coil real good real water hose