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jackofalltra · 12-20-2017, 09:02 AM

Yesterday I got my Rv out of storage garage. It started and ran ok till I got to my house & parked it. I noticed the air pressure going down to nothing. Now I have no air for brakes? I don't hear any leaks under front or rear.Acts like the air compressor is not working.Can't get anybody out to look at it. Was planing a trip over the Holidays.I have good skills and tools but don't know where to start trouble shooting.

Cooperhawk · 12-20-2017, 09:06 AM

Did you by any chance lower the jacks? If it's an HWH system when you push the button to activate that, it automatically dumps all the air and won't air up again until all the jacks are retracted.

igave · 12-20-2017, 09:11 AM

As Cooperhawk says, try to work your jacks a time or two with the engine running. If that doesn't work then the next thing I would do is double check my chassis fuses, and (I think I'm right on this) then make sure the belt hasn't slipped or broken that runs the compressor. It sure is possible the compressor has puked, but it's more likely a relay or switch or contact or something has gone bad or corroded. It's the pits these things how up just when you least need them to! Luck!!

twinboat · 12-20-2017, 10:19 AM

No belt on engine mounted air compressors. They are gear driven off the timing gears.

jackofalltra · 12-20-2017, 11:54 AM

this one is belt driven,freightliner 300isb cummings. compressor # 709ta11

jackofalltra · 12-20-2017, 12:05 PM

do you know wher i might find the relays or fuses? in back compartment there is (2) fuse blocks but none say for the compresser or air?

twinboat · 12-20-2017, 12:41 PM

Quote:

Originally Posted by jackofalltra

this one is belt driven,freightliner 300isb cummings. compressor # 709ta11

That would be your air conditioner compressor.

twinboat · 12-20-2017, 12:47 PM

Quote:

Originally Posted by jackofalltra

do you know wher i might find the relays or fuses? in back compartment there is (2) fuse blocks but none say for the compresser or air?

Because of the critical importance of your air brakes, there will not be a fuse for it.

The first place to look is at the bottom of the air dryer. It has a port that opens to purge the moisture out of the system. If that port sticks open, the compressed air just escapes.

Many of the purge ports are threaded and can be plugged with a 1/2 pipe plug. If the system works with the plug, you need the air dryer serviced.

garykk · 12-20-2017, 02:33 PM

Air bags should be on a separate tank, if you are losing all air, then as Twinboat says, look at the air drier purge.
You don’t mention if you ran the engine again and if the air pressure came up.
You should be able to hear the air escaping .

bsamole · 12-21-2017, 06:11 AM

In addition to all those great responses that you have received I would check the VDC. On my coach the VDC is located in the engine compartment. Both the front and rear airlines go to the VDC and the VDC sends a electric signal to the dashboard gages. Since your coach is newer than mine they may have replaced the VDC with some other device. Your simple test would be to start to coach pull forward one foot if the coach moves you have air pressure. If there is no air pressure your wheels will lock the coach will not be able to move.

jackofalltra · 12-21-2017, 09:05 AM

THANKS,Your spot right on,I was looking at the A/c compressor. Found the problem to be the purge valve leaking,as you said. Was able to by pass the filter & got PSI to 120.
Now will order new filter & purge valve kit.
Thanks so much.Now you made my Xmas trip to see my granddaughter in CoCo Beach a go. Happy Holidays and thanks again.