The carnot is a clockwise direction of cycle:
1. isothermal expansion at higher temperature T[sub]h[/sub]
2. adiabatic expansion to lower temperature T[sub]c[/sub]
3. isothermal compression at lower temperature T[sub]c[/sub]
4. adiabatic compression back to higher temperature T[sub]h[/sub]
Net thermal energy during each cycle is convert to work.

However, rreversed carnot cycle is

1. isothermal expansion at lower temperature T[sub]c[/sub]
2. adiabatic  compression to higher temperature T[sub]h[/sub]
3. isothermal compression at higher temperature T[sub]h[/sub]
4. adiabatic expansion back to lower temperature T[sub]c[/sub]

Net energy is required to move heat flow from lower temperature to higher so that the refrigerator can be cooler than outside.