[Fulltiming]

How long does it take to drop from 115 to 90 and how long does it take to go back to 115. Incidentally, both of these pressures are lower than my system which cycles in at 105 psi and the compressor cuts off again at 125 psi. As you are traveling down the road, the air suspension is in travel mode and the bumps and undulations in the road result in air being vented from the suspension system. Fast acting ride height valves will bleed down the air system much faster than slow acting ride height valves. My coach has the blue plastic replacement ride height valves (fast acting) and they seem to cause the air system to discharge air and thus kick in the engine driven air compressor somewhat faster than the original black ride height valves did prior to the time that they developed cracks and started leaking huge amounts of air.

When the coach is not in motion, the affect of the valves dumping when a wheel drops is eliminated so you would likely not hear a leak. If the valves are cracked, you will hear a BIG leak but you certainly have part of your air system tight if your 110 volt compressor only kicks in every hour and a half. When my ride height valve bodies cracked, it depended on the level of that valve as to whether it leaked like crazy or didn't leak at all when the coach was stationary.

Depending on the frequency of the engine driven compressor kicking in, your situation could be normal. If the frequency of the engine driven compressor cycling has changed dramatically then you may have a valve issue.