Drier then site glass why?

[Andy T]

I have always installed the site glass after the drier.This way round the site glass may show short of gas when the drier is blocked.This can catch out the less experienced engineer.Why is it fitted this way round?

[aeb200]

sightglass usually has moisture indicator on it , so shows that drier is working and is absorbing moisture!!

[adam]

sightglass usually has moisture indicator on it , so shows that drier is working and is absorbing moisture!!

i've had a system at 500 micron after performing a triple evacuation and the moisture indicator still showed wet, so i wouldn't really trust them

[Temprite]

If you install the sight glass after the drier it will always remain nice and clear to look through.

[Johnny Rod]

Presumably if the drier blocked you wouldn't know about it? The expansion valve would fully open but you'd get boiling in the line before the valve. The sight glass before the drier would still be flooded with liquid though.

[old gas bottle]

normaly the the drier gets cold and sweaty as its restricting,this carries on upto the valve as it does not have a adiquate supply of liquid,you tend to see half a glass or so sitting in the bottom,thats the reason for putting it that way round,not always the case but common.

[Perseus]

Sight glass placement after the dryer provides more useful information to the service tech.

As far as the moisture indicators go, I don't trust them either.

[Langer]

Having your sight glass fitted to your liquid line after your drier will show you if your drier is partially blocked. If your sight glass is showing a lack of refrigerant yet your receiver is full (going on bottom sight glass) then you should replace your drier.

The other way of telling if your drier is partially blocked, is you’ll notice a temperature difference across the drier. Liquid line tends to be warmer before the drier that after.