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Bad Pressure Protection Valve?

I am not sure I have a bad Pressure Protection Valve or not. 

In looking at the Air Line Connection Diagram it looks like the active air has it's own air tank that is feed from the coach via a Pressure Protection Valve.  Everything seems to be working right while driving. 

When I park and level with the engine still running and then go and start opening the slides I will hear the air compressor come on.  Looking at the air gauges on the dash I will be around 100+/- psi on both front and rear.

I am assuming that the air bladder controls are also feed from the Active Air tank since it looks like that is the only tank that the compressor can fill.

Not sure why the compressor runs when coach has good air pressure. 
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: Bad Pressure Protection Valve?

Reply #1 –
Without seeing your air system diagram, it is hard to make meaningful comments.  But I can take a shot:

It is my understanding (could be wrong) that the pressure protection valves (PPV) have one simple function: they are supposed to retain emergency operating air pressure in the tanks that supply your brakes.

If the Active Air tank is fed from one of your brake tanks via a PPV, and air pressure in the Active Air tank falls below approximately 60 psi (normal closing pressure of the PPV), then the PPV should close.  On your bigger heavier coach the PPVs might have a higher closing pressure (100 psi?) due to larger brake system demands?

With the PPV closed, if air is still being drawn from the Active Air tank to operate the slides (inflate or deflate the slide seals), then it is logical that the HWH aux compressor would run to supply the required pressure.

If my suppositions are correct, then it may be your PPVs are operating as designed. 

Would be nice if you had a pressure gauge downstream of the PPVs to independently monitor the Active Air tank pressure.  A pressure gauge on your wet tank is also handy.  When diagnosing the air system performance, you can't have too many air gauges.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
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Re: Bad Pressure Protection Valve?

Reply #2 –
Quote from: Chuck & Jeannie –

If the Active Air tank is fed from one of your brake tanks via a PPV, and air pressure in the Active Air tank falls below approximately 60 psi (normal closing pressure of the PPV), then the PPV should close.  On your bigger heavier coach the PPVs might have a higher closing pressure (100 psi?) due to larger brake system demands?

With the PPV closed, if air is still being drawn from the Active Air tank to operate the slides (inflate or deflate the slide seals), then it is logical that the HWH aux compressor would run to supply the required pressure.

If my suppositions are correct, then it may be your PPVs are operating as designed. 

I was thinking the PPV was set at 55PSI, but do not know that for a fact.  I will have to find out what it is set for.
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: Bad Pressure Protection Valve?

Reply #3 –
Quote from: turbojack –
I am not sure I have a bad Pressure Protection Valve or not. 

In looking at the Air Line Connection Diagram it looks like the active air has it's own air tank that is feed from the coach via a Pressure Protection Valve.  Everything seems to be working right while driving. 

When I park and level with the engine still running and then go and start opening the slides I will hear the air compressor come on.  Looking at the air gauges on the dash I will be around 100+/- psi on both front and rear.

I am assuming that the air bladder controls are also feed from the Active Air tank since it looks like that is the only tank that the compressor can fill.

Not sure why the compressor runs when coach has good air pressure.
What is the cut in pressure of the 12v air compressor set at?
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Bad Pressure Protection Valve?

Reply #4 –
Quote from: craneman –
What is the cut in pressure of the 12v air compressor set at?
I have no idea at this time.  There is no pressure gauge on the active air tank. I am going to have to buy a gauges and mount at the pump. 
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago
 

Re: Bad Pressure Protection Valve?

Reply #5 –
Found the air diagram for my unit.  Looks like Active Air gets it's air from both the front and rear air tank with PPV in each I do not think both PPV valves would be bad.

Also says pump kicks in at 85 psi & cuts out at 115.  I can see the system trying to level and the pressures go below 85 for a short time thus causing the compressor to start. .
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago