H-VAC & R question?

Question

When you put the sightglass (moisture indicator) and filter dryer in the liquid line of a refridgeration unit, what should be first and why?

Answer 1

I would put the dryer first. The sight-glass would then show if the dryer had become saturated and passed moisture through. However, in a closed system such as this, it doesn't much matter.

Answer 2

Don't ask me I don't know

Answer 3

The filter/dryer should come prior to the (moisture indicator). Ideally, the hvac system shouldn't have moisture in it at all. (one of the reasons that a good vacuum should be drawn and held for a period of time on the system prior to charging with refrigerant) However, this is virtually impossible to achieve even with the best vacuum, as some molecules of water vapor will remain. The Filter/Dryer (accumulator) is designed to both filter the particles of debris and absorb the molecules of water as the refrigerant passes through it. If the moisture indicator is prior to the filter then it will absorb these molecules instead, thus giving you a premature warning indication. (aka color change)