HVAC Service Intervals: When You Change the Oil, Check the Dot

Here’s a simple tip to help your air conditioner deliver the service life you expect: check the dot.

The “dot” is the sight glass on the receiver-drier’s moisture indicator. Inspecting the dot in the sight glass whenever you conduct an oil change or other routine preventive maintenance is a simple, effective way to prevent a catastrophic failure of your HVAC system, says Norm Baker, manager of aftermarket sales for Red Dot Corp. Based in Seattle, Red Dot makes heating and air-conditioning systems, components, and replacement parts for heavy trucks and other commercial vehicles.

A receiver-drier contains desiccant, a chemical that attracts moisture. When desiccant becomes saturated, moisture in the system is free to combine with refrigerant and turn into corrosive hydrofluoric acid. The moisture indicator provides a quick visual cue about the refrigerant’s condition: a blue dot means the refrigerant is dry; pink, white, or grey indicates acid or moisture in the system.

“Checking the moisture indicator involves nothing more than a glance for a blue dot,” says Baker. “But it can save you hours of unexpected downtime.”

The receiver-drier should be replaced once a year, but often it’s not changed until the air-conditioning system fails. Checking the sight glass during an oil change or any scheduled maintenance procedure means the truck can receive necessary service while it’s there in the shop, before moisture and acid damage critical A/C components and lead to a failure on the road. 

Red Dot offers a family of exceptional high-capacity replacement receiver-driers through more than 175 distributors in the United States and Canada. Red Dot receiver-driers are OEM-quality, delivering the same level of performance as the originals, at a value-oriented price.

Preventive maintenance for your A/C system starts with a glance at the receiver-drier’s moisture indicator. “Get into a routine where you check the receiver-drier sight glass whenever you change the oil or schedule preventive maintenance,” Baker says. “Avoiding costly A/C repairs and unexpected downtime can be as simple as checking the dot.”