accap - Page: 1 of 1

Air Conditioner Capacitors

There are two critical specifications that need to be identified when looking to replace an air conditioner's fan or compressor run capacitor, the voltage and the capacitance rating in microfarad (uF or MFD). The physical size and shape (round/cylindrical or oval) is irrelevant except for mounting considerations and you will often find newer capacitors considerably smaller then old ones of the same rating.

As a replacement you can use an alternative of a higher voltage rating without any problems but the capacitance should be within 10 percent of the original but an exact replacement is always best.

Some models may utilize a 'dual' capacitor where the compressor and fan motor capacitor are built into one. On this type you will see 3 groups of terminals across the top of it. There will be one set of common terminals, one group for the fan motor and another for the compressor wiring.

The common terminals on a dual capacitor will usually be indicated with the letter "C" near the associated terminal set, the fan side may or may not be indicated. The compressor will almost always be indicated with the word "herm" (short for hermetic) indicating part of a hermetically seal system (which the compressor is part of).

Dual capacitors are usually considerably more expensive to replace than single purpose ones.