Air Dryer Purging Every 30 Seconds (Keeps Popping Off)
The air dryer may or may not be in your RV but when it is, it performs an important task. Its job is to keep the air tanks for your air brakes free of moisture. The good news is that they do not have to be serviced very often.
This problem could be due to a failed governor. This is a little part of the compressor intake line. A simple replacement of the governor may stop the problem or it may not. If the latter, then you will need to keep searching for the failed part.
To learn more about this problem, just continue to read our article. It explores the topic so you have the best information to handle the fix when it happens to you. Don’t forget to check the purge valve to make sure it is working as it should.
How Often Should My Air Dryer Purge?
It should not be purging every 30 seconds. One report has said that the air dryer should have at least 15 minutes in between purges when driving down the highway.
There are steps to take to see what is causing the problem if your air dryer fails to meet this minimum requirement:
- Turn off the power to the dryer. In many makes and models, both towers will pressurize.
- If air is leaking from either exhaust muffler, you probably have a bad purge valve. Repair or replace the purge valve(s).
- Also check the solenoid exhaust ports. While in power-off mode, no air should be bleeding from the control solenoids.
- If any air is exhausting from one or more solenoids, replace the leaky valve.
** taken from https://moistureboss.com/blog/air-dryer-constantly-purging-a-few-troubleshooting-tips/
These steps are for the drying tower. It can fail and go bad on you at any time. Also, you should check the air mufflers and all the filters in the system. By keeping those clean and up to date, your air dryer should last you a long time.
If you are not a mechanic or even a good mechanic, find an air brakes specialist to help you with this major RV part. If you have an accident, you may be at fault if you do not have the proper training for air brakes.
At What PSI Should The Air Dryer Purge?
This may depend on which company built the air dryer and which model it is. We have seen the air purge at 140 PSI, 125 PSI, and just over 90 PSI. It seems that 130 to 140 PSI is normal but the dryer should not be purging itself at will.
When it does, and some owners have experienced this every 5 to 7 seconds, you have a faulty part somewhere in the system. Most people start with the governor and say to either replace it or put a pressure release valve on the outlet line from the governor.
Another source can be the head of the compressor is not functioning. Or the compressor has just worn out. There are several more parts you can check, like the purge valve to see if it also has worn out and not releasing the air when it is supposed to.
Other sources may be the air lines. They may have rotted and sprung a leak. Check all your lines as one owner found a hairline crack in one of his lines that was causing him a lot of purge issues.
Some purge valves are set to release air at 150 PSI so check your settings to make sure they are where they are supposed to be. Air dryer purging every 30 seconds
The Air Dryer Purges Every 10 Seconds
First look at the governor and see if that part has failed or not. If not then you move on to the next possibility which would be leaks in the line somewhere. A good spot to look for the leak will be in the signal line between the dryer and compressor.
If there are no leaks, then check the unloaders inside the compressor. It is easy for them to capture some carbon and get stuck open. Those parts would need a good cleaning to see if they will work right or not.
Then, the problem may be with the air dryer itself. As one owner reported his line was purging every 10 seconds and he got a lot of free advice. But his air dryer was 5 years old.
He suggested that he should replace the air dryer and was scoffed at for making that suggestion. Despite the contrary opinions, he went ahead and changed the air dryer. The result was the problem was solved.
Sometimes it is the air dryer being too old to do its job. The point of all this is that there are numerous sources for this problem and you can’t rule any option out until you have checked them all and found the failed part.
You will get a lot of free advice and most times this free advice is on target. But don’t let the advice stop you from checking all the parts in the air dryer system. You never know until you check what will be the source.
You can rebuild the air dryer using a kit as one owner did, but sometimes the kit may not replace the bad part. This problem can be a time-consuming search.
The Air Dryer Purge Valve Stays Open
This could mean that there is a problem with the snap ring or the O ring. If these two small parts have gone bad, they can hold the purge valve open and let the air out of your system.
Replacing those parts and lubing them well should solve the problem. If not then you may have a problem with the after-cooler. There are kits available to rebuild that part.
Some people are very anti-brand at times. One owner suggested that if the air dryer is made by Haldex then you should through it away and replace it with a Bendix model.
That is only a good repair when the Haldex model is bad. Replacing the air dryer or the purge valve with another brand is a good option when you are not satisfied with the performance of the original air dryer or purge valve.
It is not a solution if you just do not like a specific brand. That move may not solve the problem. What is not normal is if you have to replace the filter, valve, or drier frequently.
If you are doing that, then you have a problem with the compressor. But that is another issue altogether. If you are working in a dirty environment like the local dump, then this may be a common problem.
The dirt will get inside the valve and cause it to stay open. The best fix is to replace the valve every time it gets too dirty.
Understanding The Air Dryer System
For many people, this is a system they do not understand. They are not mechanics and do not know how their air brake system works. The system is fairly simple.
Ambient air is compressed and then sent to the storage tanks to be used when the brakes are applied. To control this supply of air, the governor monitors the air pressure and sends out a signal to the compressor when it gets too high.
The compressor then unloads the excess pressure and then starts to build it back up again so the brakes can be used. The reason there is an air dryer in this system is that the air brakes and the system needs clean and dry air.
If there is moisture in the system, then that could freeze and prevent the brakes from working. Other fluids can damage seals and other key parts. While air dryers are not mandatory most air brake builders install them as a safety devices.
The basic maintenance you need to do is to change those filters on a regular basis to keep the system working smoothly.
Two Diagrams To Help You Understand The System
Here are two diagrams that help you understand all the parts involved and how the system is set up. If you are not a mechanic, these diagrams should help you know if the mechanic knows what he is talking about or if they are trying to pull a fast one on you.
The first is the air dryer
The second is the whole system
Some Final Words
Air breaks are a very good system of brakes when they are well maintained. Sometimes, like any other device, a part will break and you have to track it down.
If you are not a mechanic, then that can be a time-consuming chore. The reason for that is that there are many parts that can go bad and if it is not the most common one, then you have a tough search on your hands. Sometimes replacing the entire air dryer is the best solution.
Have a good air brakes technician handle this problem for you.
