How to figure out what is wrong?

My kit is about 6yrs old. The last few weeks my horns would work fine and then the next time it sounds really muffled. I put a pressure gauge on the tank and when it is about 145psi it sounded fine but once it drops below 140psi it starts sounding bad. When it first started it would sound bad even when the tank was just filled. Does this sound like the pressure switch may be bad or could the diaphragms be bad?

The gauge is telling you that the proper amout of air is in the tank, so the pressure switch is good. (I assume it’s 150psi pressure switch)

So yeah, something with the horns, or getting the air to the horns. After 6 years, I would wonder about junk in the airline blocking flow… Just an idea-

Thanks. I hit the horn several times leaving work today. Sounded loud and crisp. The horns have been on 4 different vehicles(actually it’s been more like 8yrs now that I think about the different vehicles), each time there were new lines installed.

I thought about cleaning the diaphragms of the horns but i’m not sure if I would need new gaskets or is it sealant that I would need when re-assembling?

Are they Shockers? Not really any info on taking those apart since it voids the warranty.
I’d give HB a call and see what they say.

OK, thanks. I wouldn’t think they were under warranty after all these years and the place I purchased them from has closed.

I would start by blowing each individual horn by itself. Then by process of elimination you can may find that one or more bells are fouled. They can be tuned.