patwhite Report post Posted November 13, 2020 Tried to go on a trip today but I have no chassis air. Both air gauges read zero, the low air horn is on, and the low air warning light is on. No brake line air, no suspension air. Emergency parking brake is engaged. RV stuck in driveway. Temperature today in the mid 40's. The repair shop thought that air system governor might be frozen. I do not hear any air leaks in the RV or under the frame. Where is the air pump governor on a CAT 326? Shouldn't running the engine at idle for 30 minutes thaw it out? Next step, putting heat lamp on the air dryer. Any other suggestions? Thanks, Pat Share this post Link to post Share on other sites
kaypsmith Report post Posted November 13, 2020 The last time that this happened on my coach, the air drier purge valve was stuck open. If I'm not too badly mistaken, the governor is actually part of the air pump. Share this post Link to post Share on other sites
rayin Report post Posted November 13, 2020 (edited) The air governor looks like this depending on chassis and engine it is mounted on the air compressor or a stand-alone. This is a utube video of an air governor installation How long since you had the air dryer serviced? A faulty air dryer can cause this. With the proper fittings the air dryer may be bypassed to test the system. If it builds air pressure when the dryer is bypassed, replace the air dryer, which is usually cheaper than having it totally rebuilt. That said, the air governor will not allow the air compressor to build pressure while the jacks are down on my Spartan chassis. Edited November 13, 2020 by rayin Share this post Link to post Share on other sites
jleamont Report post Posted November 13, 2020 One thing to add, the signal line from the air dryer to the governor is another culprit, they are often routed in such a poor manner that causes chaffing. All of our air lines to the governor that is remotely mounted are braided stainless steel, I suspect this was a problem area with the previous owner, I doubt it came that way from the factory. As mentioned faulty air dryers from neglect are another huge issue. Air dryers tend to be one of the most forgotten about components on an RV until they leave you stranded or contaminate the air system. Share this post Link to post Share on other sites
jleamont Report post Posted November 13, 2020 On a CAT the governor (if mounted to the engine compressor) would be on the passenger side of the engine circled in the picture. Mounted on the engine this would hang off the rear of the compressor. Share this post Link to post Share on other sites
dickandlois Report post Posted November 13, 2020 Pat, How long sense the Air Dryer been serviced? Has the Air dryer ever been replaced? It maybe much less expensive to have the dryer replaced, rebuilt units are not expensive when one figures in the labor to resurrect the old one. Rich. Share this post Link to post Share on other sites
patwhite Report post Posted November 13, 2020 Thanks for all of the replies. The air dryer was last serviced three years ago. I have been out of town all day, but will check out the air dryer and report back Saturday night. Hoping for warmer weather, in the 50's tomorrow, to thaw out any potential frozen lines. Pat Share this post Link to post Share on other sites
rayin Report post Posted November 14, 2020 14 hours ago, jleamont said: One thing to add, the signal line from the air dryer to the governor is another culprit, they are often routed in such a poor manner that causes chaffing. All of our air lines to the governor that is remotely mounted are braided stainless steel, I suspect this was a problem area with the previous owner, I doubt it came that way from the factory. As mentioned faulty air dryers from neglect are another huge issue. Air dryers tend to be one of the most forgotten about components on an RV until they leave you stranded or contaminate the air system. There is a utube video about governor problems, the man in the video displayed a worn braided SST covered air line that had failed inside yet appeared OK on the outside. It was the problem instead of the governor. I forget where that video is now, the video was about a HDT. Share this post Link to post Share on other sites
jleamont Report post Posted November 14, 2020 11 hours ago, rayin said: There is a utube video about governor problems, the man in the video displayed a worn braided SST covered air line that had failed inside yet appeared OK on the outside. It was the problem instead of the governor. I forget where that video is now, the video was about a HDT. YUP, one reason I’m not a fan of those hoses. While they are less likely to chafe an internal failure is possible. Share this post Link to post Share on other sites
rayin Report post Posted November 14, 2020 9 hours ago, jleamont said: YUP, one reason I’m not a fan of those hoses. While they are less likely to chafe an internal failure is possible. Found that video: Share this post Link to post Share on other sites
patwhite Report post Posted November 19, 2020 (edited) Problem fixed! Thanks to all for your time and info. Talked to my diesel repair shop and he led me through bypassing the air-dryer. Two new wrenches, $10 in fittings and dryer is bypassed. I now have 130psi to the coach again. Driving the RV to the repair shop next week for a new air-dryer and my annual fluid/filter changes. Pat Edited November 19, 2020 by patwhite Share this post Link to post Share on other sites
jleamont Report post Posted November 19, 2020 3 hours ago, patwhite said: Problem fixed! Thanks to all for your time and info. Talked to my diesel repair shop and he led me through bypassing the air-dryer. Two new wrenches, $10 in fittings and dryer is bypassed. I now have 130psi to the coach again. Driving the RV to the repair shop next week for a new air-dryer and my annual fluid/filter changes. Pat Glad to hear you are on the path to a permanent repair. Share this post Link to post Share on other sites
