Re: Air pump
Reply #1 –
Two things make the HWH compressor come on assuming power is available ...
1) the pressure switch falls below its minimum setting.
2) the HWH computer tells the pump to come on if air is required for raising one side or the other or one end or the other.
#2 happens in manual mode (in my coach) if you push a button to raise either side or end no matter what the pressure.
Look at your air system diagram. Depending on check valves and pressure protection valves the leveling manifolds could get air from the service tanks. The HWH compressor (normally) does not supply air to them. This air may be sufficient to help with leveling but the min pressure for levelling is about 90 psi. Not all coaches are the same. 2001 U320 have 3 different diagrams in one year.
Look at your wiring diagrams carefully, just interrupting power to the compressor does not interrupt power to the control side of things. The pump might not run but the switch says run and the water trap exhaust solenoid is powered. It gets very hot.
Interrupt power going to the essex relay may be better. Lots of different ways this was wired up over the years. Check your coach for the way it is connected.
Topic: Air pump