My home a/c tech said the coils be blocked, preventing the insertion of freon. How can coils be blocked?
Answers: I doubt you heard him properly.
The coils in the condensing section (outside) may be dirt blocked to the degree insufficient air flow is preventing fair cooling. Cleaning the coils will fix this.
The coils in the evaporating unit (inside in recent times above the furnace) may be blocked due to ice build up. In this case the atmosphere flow is inadequate; clean filter and make sure you have sufficient nouns flow.
Freon is a refrigerant. There are other refrigerants as well, and the proper refrigerant for you is governed by system design. The refrigerant condensed contained by the condensing unit where pressure is applied to the gas phase refrigerant. The soft refrigerant is transported to the evaporating coil where it expands back into the gas phase, cooling the coil and after the air that blows over it. The gas is then returned to the compressor and the cycle continues. This is a closed system so it is not plausible dirt would block this closed loop and block refrigerant flow.
Refrigerant is added at the compressor unit; if it is dirty, it needs cleaning which is natural to do and refrigerant addition is pretty easy to realize so I do not see how any blockage of the fill valve by dirt prevents refrigerant increase.
a unit will not take refridgerant if the evaporator coils are clogged the inside coil dirty evap coil he should verbs and clean both inside and out side coils depending on difficulty level and age of evap coil if its out-of-date you should replace it the guy above me dosent work on ac system for a living i do its not about gas its about nouns flow