Air pressure in secondary line won't go up to normal level

When I was driving to the truckstop, I thought that maybe the air compressor on the truck is defective. But now I don't think that the air compressor is defective. If the air compressor was defective, I don't think the primary air line would have 120 psi with the engine turned off.

I think you are right that there is a leak of some kind.

 

@Rideandrepair
@Ridgeline
Does anyone have any idea as to why the air pressure in both the primary and secondary air lines rose almost to normal pressures when I idled the truck engine for about two or three minutes to microwave food last night?

The mechanics have not worked on the truck yet. I don't get it. I am baffled.

 

About 4 days ago, I accidentally drove my semi-truck all day with the air bags dumped. Do you think that my driving with the air bags dumped all day could have caused the leak?

@Ridgeline
@Rideandrepair

 

20240914_091207 by expedite_it posted Sep 14, 2024 at 8:13 AM

The photograph above is a photograph that I took of my truck about an hour ago. The air pressure in the secondary dropped overnight to 25 psi.

I found the photograph below this sentence on my cell phone. The photograph below is a photograph of a different Freightliner truck than the Freightliner truck I have now. On this Freightliner truck four years ago, both the primary and the secondary air pressures were at about 120 psi with the engine off. I think that is how my current truck would normally be with the engine off.

20201216_131354 by expedite_it posted Sep 14, 2024 at 7:33 AM

---------------
So the two photographs on this post are photographs of two different trucks, but both of the trucks are Freightliner Cascadias.

 

I do have a suspension switch.

I'm assuming "dump your suspension switch" means dump the air bags. I suppose I should perform that test with the truck parked and the engine idling; correct?

 

If the pressure does not go back to normal when i dump my air bags, what does that indicate? Where would my leak be then?