Filter Driers?
Before Or After The Sight Glasses?

Should filter driers be installed before or after the sight glasses?

That's a good question.

Let's examine each location and the information it provides.

If the drier is installed before the sight glass:

1. A flashing sight glass usually indicates-

a. low refrigerant charge or

b. restricted drier.

2. A clear sight glass usually indicates-

a. properly operating system

If the drier is installed after the sight glass:

1. A flashing sight glass usually indicates-

a. low refrigerant charge

b. properly operating drier

2. A clear sight glass usually indicates-

a. no information can be determined about the refrigerant charge (it depends upon the status of the drier)

b. restricted drier

Over the years, I have always installed the sight glass after the drier.

The information provided about the refrigeration system is more useful and reliable.

I like to eliminate as many alternatives as possible!








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