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Help! Air Pump Problem

We recently purchased a 2003 U270 36' one slide unit from MOT.  I had the unit inspected by an ex-Foretravel employee who not only inspected it but test drove it.  Other than a few minor issues, the coach appeared to be in good condition.  We live in the Dallas area and have taken one small trip to Galveston.  The coach drove great and everything seemed to be working ok. 

Today, I went over to storage to load some gear and the coach adjusted the level and then the air pump went on.  This had happened before and I assumed that was normal.  Usually, the pump would run for a short period and then turn off.  Today, the pump would not shut off.  I let it run for approximately 15 minutes and it would not stop.  The pump was getting hot and I got worried.  I found a fuse in the wiring and pulled it, that sopped the pump. 

What should I do now?  I'm not a mechanic but I can handle basic things.

Thanks,
Jimmy
Jimmy

Margie and Jimmy
2003 U270 36' (one slide)
1998 U295 36' (Sold 2019)

Re: Help! Air Pump Problem

Reply #1 –
Sounds like you have a good air leak. It could be a fitting leaking or a bladder that has a tear and leaking. Ones more familiar with your year will Chime in.
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: Help! Air Pump Problem

Reply #2 –
Quote from: jimmy_walther –
Today, I went over to storage to load some gear and the coach adjusted the level and then the air pump went on.  This had happened before and I assumed that was normal.  Usually, the pump would run for a short period and then turn off.  Today, the pump would not shut off.  I let it run for approximately 15 minutes and it would not stop.  The pump was getting hot and I got worried.  I found a fuse in the wiring and pulled it, that sopped the pump. 

So, likely a leak, but first thing to check is if the N/O solenoid valve on the condensate bowl isn't closing when the aux compressor is running.  It's a common failure.  It's normally open but closes when the compressor runs.  If there's a crack in the bowl or there's debris on the seat, it will leak air and the compressor won't achieve pressure.  Since this bowl sees significant temperature shock (rapid cooling when then solenoid valve opens to blow off condensation), it's common to develop cracks in the bowl where the solenoid valve screws in. 

Also recently, someone found the o-ring for the bayonet mount of that bowl wasn't sealing.  Auxiliary Air Compressor only able to pump up to 60 PSI

It's in the aux compressor bay, looks like this:

Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Help! Air Pump Problem

Reply #3 –
Thanks, I'll go take a look tomorrow.
Jimmy

Margie and Jimmy
2003 U270 36' (one slide)
1998 U295 36' (Sold 2019)

Re: Help! Air Pump Problem

Reply #4 –
Another possibility is a sticking pressure switch. I had this problem on our coach and have seen it many times in other applications. Sometimes the pressure switch will stick once and never be a problem again, and sometimes it is a sign the pressure switch is failing.
Dave and Kathy Bennett
2004 U270
Build #6253
1600W Solar
700 AH Battle Born Lithium
2015 Jeep Wrangler

No matter what happens, remember you always get the trip out of it.

Re: Help! Air Pump Problem

Reply #5 –
Thanks, how do I identify the pressure switch?
Jimmy

Margie and Jimmy
2003 U270 36' (one slide)
1998 U295 36' (Sold 2019)

Re: Help! Air Pump Problem

Reply #6 –

This is the replacement I used on my Thomas.    Should look like that.  Easy fix.  Also recommend you add a pressure gauge at the same time if replacing it.

Pressure Switch, DPST, 1/4" FNPS, Diaphragm 9013FHG2J27: Electrical Boxes:...


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Joe Phebus and Jaime Trujillo
2002 U270 3410  Build: 5953 Motorcader # 18595
2100 W Solar, 600 AH Battleborn Batteries,  Victron Multi-Plus II 3000 Inverter, Cerbo GX, & MPPT Chargers
1992 Geo Tracker