Today we will help make identification on an air dryer for your commercial truck. The biggest “offender” of air system problems in your truck is not servicing or taking care of your air dryer. Your air dryer’s main purpose is to pull the moisture out of your air system so it doesn’t travel through your valves.
The most common air dryer there is, is called the Bendix AD-9. To identify, notice the big dome cam, bolts going around the bottom, and an offset purge valve. This purge valve will release the extra air from the compressor by purging the extra air when the air dryer has enough air in it. This also has a heater in it to keep it heated so it doesn’t freeze up in your dryer itself.
To service the inside of the can of the air dryer, remove all the bolts all the way around the can. Inside there’s what is called a desiccant cartridge. This is the filter of the drier. If your truck is purging a lot and/or not drawing, it’s time to change the cartridge. It is recommended to change the cartridge twice a year, once in the spring and once in the fall, if your truck runs a lot. If your truck sits a lot, once a year is fine.
Note: Do not throw them right away. A lot of the time there’s a core deposit included in the price.
Another type of air dryer is called the WABCO System Saver 12. It’s a lot smaller compared to the Bendix 89. A lot of newer trucks have a mounting of a triangular shape and tag will say System Saver 1200. This is no more than a spin on an oversized oil filter. Oil filters are also replaceable and should be done once minimum, twice a year maximum.
If you’re having trouble identifying the type of air dryer in your truck, check out our cheat sheet designed for most common air dryers.