Topping off gets the customer cooling and guarantees another call later, because refrigerant does not get used up: if it is low, it leaked. Good techs leak search before adding refrigerant, and rules for larger commercial systems require leak rates to be tracked and repaired. The phrase carries a mild sneer when one tech describes another's work.
Last company just topped it off every June for four years, there's a leak in the evaporator and nobody looked.
Systems don't use refrigerant; if it's low, there's a hole somewhere.
Also heard as
- top it off
- topping off
Related terms
Weigh in
To charge a system with a measured weight of refrigerant on a scale, set by nameplate charge and line set length.
Bubble it
To leak-check a joint or fitting by brushing on soap solution and watching for bubbles.
Refrigerant
The working fluid that carries heat around a refrigeration or air conditioning system by boiling and condensing.
Starved
Describes an evaporator not getting enough refrigerant, so part of the coil runs warm and superheat is high.