Last time it got cold i was call about a 96 FL80 its brakes wouldnt release. They got them working that day and the next morning they called me agin so i went and by then they had moved it to a heat shop. They said they didnt fully release but was able to move it. I serviced the dryers filter and purge valve. It hadnt been done in years. Today i was there working on some thing for them i think it was the first cold day on the dry work and they went to use this truck and the brakes wouldnt release. I went and looked at it and dryer was blowing air out it showed 60 psi. I went to pull the purge valve and i thought i heared air leaking from some were up front of the truck. I pulled it and saw notheing so i replaced it and restarted the truck it worked.
I have never had any luck "servicing" an air dryer. If a truck I have does not have an AD-9 Bendix dryer, whatever it has gets tossed IMMEDIATELY and changed over. Every winter the truck shops around here carry new ones for around $150. Running trucks for over 20 yrs, have never had an AD-9 fail on me. So after you serviced the dryer, did you drain all tanks, put a bunch of air guard into line between dryer and tanks, disconnect line from compressor and dryer, put air guard in and blow out with air hose? Then, after you hook everything up, run for a while, drain tanks again, then add some more air guard into line between dryer and tanks? This is what I do on a problematic truck and usually after this you never worry about it again as long as you change dryer every two years.
I agree, if the dryer hasnt been working for some time the system is full of water.
Yep, all needs to go, otherwise you're just wasting your money on the new dryer.
Yes we did blow the lines and drain the tanks. We use a chemical for air brakes but i dont know what it was called. Today it did about the same thing and i found the govener was leaking so i replaced it so now i dont know if it was a water problem this time. I have been there this week because there 2 mechanics have been gone. Today another truck had brake problems and i havent found out yet when its dryer was serviced. This place dosent have the best records of what has been done this is going to change.