Dear Flatlander: I goofed. You are correct. Another of my senile moments.

Dear TEd: I kid you not. If you press a fingertip over air outlet of a bicycle pump firmly, depress the plunger forcefully, and then let up finger over air outlet just enough to let a small amount escape under pressure, and you can indeed get a burn and blister, though you may have to depress plunger several times. I have experienced this. Remember the mechanical equivalent of heat. Count Rumford discovered that if a drill for boring cannons got dull, so that no more metal was removed, heat continued to be produced as long asd you kept turning the drill, because the work was being converted to heat.He could keep water boiling away as long as the drill was turning while forced against the metal of the cannon being made.
The same effect takes place in an refrigerator compressor. But when you cool the compressed gas to environment temperature, and then let it expand in the food compartment, it can take up heat. But in a hot environment, the compressor has to work harder. I think this is what the engineer told Wordwomd.