Diagnosis
The unit is hitting a high-pressure limit and shutting the compressor off to protect itself. This is almost always caused by insufficient exhaust or an over-temperature condition.
How to Fix It
Verify the exhaust hose setup. The larger, uninsulated hose (exhaust) must be the one venting hot air OUT. Ensure it's not more than 5 feet long, is fully extended (no sharp bends), and the window seal is airtight. Any restriction causes heat buildup and a pressure trip.
If That Didn't Work
The ambient temperature might be too high for the unit to operate continuously. If your room or outside temp is consistently above 95°F (35°C), the compressor will cycle on and off more frequently to prevent overheating.
Heads Up
This cycling can look like the unit is broken, but it's a safety feature. Let it sit powered off for an hour if it trips, then restart. If the problem persists in normal temps, the condenser coil might be coated in dust—this requires opening the case to clean.