We were beginning to experience problems with releasing the parking brake in the morning, especially if the coach had sat parked for more than a day or two. The air system would pressurize normally but when you'd push down on the "big yellow button" there would be a wheezing sound as if air wasn't flowing into the brake chamber properly. This would by accompanied by sounds (in the coach) of air leaking and the system pressure would fall almost faster than the compressor could supply it. The parking brake light would blink or remain on.
After several applications and releases of the valve we had been able to get it to function each time this happened, and once we could get it to work it would work fine for the rest of the day. But we were leery of it one time not releasing at all. Furthermore, we had inadvertently driven with it on in a parking lot after the brake light came back on after having been off. We already had pad a lot last year to replace most of the actual brake parts and didn't want to go through that again.
We had the coach in for other service and decided to replace the valve even though the shop was unable to reproduce the symptoms. For a part that cost ~$120 it seemed like the right thing to do rather than get stuck some morning without the ability to move. The part is made by a company in OR, but my invoice from the shop doesn't show the name.
