Why Frigidaire Upright freezer FFU20FC4AW2 compressor starts and stops

It is on the back wall, about 2/3 of the way to the floor on the right hand side... Knob will look like this: Frigidaire Freezer Control Knob 216707200

You probably have food in front of it!

If the control is "ON" and the compressor is not running, you will need a start relay... Make sure you didn't accidentally turn it off by pushing food against the control knob!

it could be the compressor out or the starter pack or install hard start on it to start the compressor if it takes off good deal if not time for a new freezer

Hello - When was the last time you cleaned the condensers? You may do so by removing the toe grille and use extended vacuum attachment and condenser cleaning brush to remove dust buildup from condenser coils usually located on the left side underneath. If you hear the compressor running and if it is providing warm air then that means it is operating correctly and the sealed system is removing heat from the cabinet. Fan motor/evaporator may be the primary issue. However, if you do not hear the compressor and the unit is blowing room temperature then the unit may possibly have a sealed system leak, faulty compressor or overload relay. Contact a professional to move forward accurately from this point.

See previous answer - suspect short of gas.

besides hitting the compressor with a hammer. unplug and lay on its side for 2 hours then upright for 24 hours plug back in. Never ever unplug a freezer

I’m happy to assist further over the phone at https://www.6ya.com/expert/james_1cb31da1bc8c6102

Start relay.

It sounds as if your compressor it's running. This could be a bad compressor, bad capacitor, bad thermostat. See that there are no fans or defrost, it is one of the other. I would start with checking the capacitor. You can replace it with a Supco 3 in 1. It cost around $30.00. Anything else is going to start costing $100.00 and more. If you need a freezer that big, I would have it fixed unless it ends up being the compressor.
Please rate solution

Sounds like the timer could be getting stuck and not releasing the defrost cycle. If you have to do it again, you should have the timer checked, or just replace it.

IF THE FREEZER IS AUTO DEFROST, DO YOU SEE A FROST BUILDUP ON THE BACK WALL? IF SO, YOU NEED TO DIAGNOSE THE DEFROST FAILURE. THERE ARE THREE ITEMS TO THE DEFROST CIRCUIT. THE TIMER, HEATER, AND BI-METAL. FIND THE TIMER, USUALLY ON THE BACK OF THE FREEZER DOWN IN THE CORNER NEAR THE COMPRESSOR. IT WILL HAVE A CONNECTOR WITH FOUR WIRES ATTACHED TO IT. IT HAS A KNOB THAT CAN BE TURNED TO PUT IT INTO A DEFROST CYCLE. WITH THE FREEZER RUNNING, START TURNING THE KNOB UNTIL THE COMPRESSOR STOPS. THAT WILL BE THE DEFROST CYCLE. THEN WAIT 5 MINUTES AND LISTEN IN THE FREEZER FOR A SIZZLING NOISE AND LOOK FOR A GLOWING FROM THE BACK BOTTOM. IF THE HEATER IS ON, THE TIMER IS THE PROBLEM. IF THE HEATER IS NOT ON, THE HEATER OR BI-METAL IS AT FAULT.
IF THE FREEZER IS NOT AUTO DEFROSTING, CHECK TO SEE IF THE COMPRESSOR IS RUNNING. IF IT IS, ARE THE SHELVES ALL FROSTED? IF NOT, YOU HAVE A SYSTEM FAILURE. IT COULD BE A LEAK, RESTRICTION, OR FAILED COMPRESSOR.