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Topic: Thomas Model TA-4101-12vdc Auxiliary Compressor Question (Read 707 times) previous topic - next topic

Thomas Model TA-4101-12vdc Auxiliary Compressor Question

I just recently bought a 2007 Foretravel Nimbus 336, and have a lot to learn.  This is my first Foretravel Motorhome.  I have some questions concerning the HWH Air Auto Leveling System.  I just had my coach serviced which included replacing the engine air dryer filter.  My coach has a Thomas Model TA-4101-12vdc Auxiliary Compressor (pdf attached).  Before I had my coach serviced, when I was parked on my RV Lot with the coach leveled, several time a day the 12vdc auxiliary compressor would come on for about 90 seconds.  I'm assuming it was adjusting the levelness of the coach.  Since I had the coach serviced (about 2 days) the auxiliary compressor has never come on.

Now I'm wondering if the auxiliary compressor has stopped working.

Is there an easy way to determine if the auxiliary compressor is still working?      Any suggestions?

I wanted to check the fuse for the auxiliary compressor, but could find one, any suggestion where to look?

Any help would be greatly appreciated!!!!


John

Re: Thomas Model TA-4101-12vdc Auxiliary Compressor Question

Reply #1 –
If it's like mine you can remove the gray plastic cover from the pressure switch which will allow you to push the points together manually for a moment to see if the compressor starts up. Mine has an inline fuse behind the pressure switch. You may have to sort through all the excess wiring to find it.

Re: Thomas Model TA-4101-12vdc Auxiliary Compressor Question

Reply #2 –
Check your repair order. Likely the technicians did a leak check while working on your coach and found and fixed air leaks Praise and thank the lord for less cycles of the onboard compressor What do you main air tank pressures read?
Tim Fiedler    2025 LTV Unity MBL on Order
2000 Chevy Tracker 2 Door Convertible 4WD Now lifted 4.5"
1985 Citroen 2CV6 Charleston
Murphy Rebel on wheels with 175HP Titan
Cessna P337
1980 48' Westport MY (!/4 Share)

Re: Thomas Model TA-4101-12vdc Auxiliary Compressor Question

Reply #3 –
John,

Although your coach is much newer than ours, I believe the HWH leveling systems work basically the same.

The HWH auto leveling function seeks to maintain (obviously) a level condition.  It does this in two distinct stages.  Once activated, IF it detects a "out of level" condition, it will correct by releasing air from the air bags, as required.  The distinctive hissing noise that is made is sometimes said to be the coach "marking it's territory" (a reference to 4-legged critters).

The system will continue to correct attitude by releasing air, until this action no longer works.  The air bags in one or more corners of the coach will be almost completely deflated.  At that point, the system goes to "Plan B" which is to add air to the air bags, as required.  This is when the aux compressor goes into action.  The compressor will run whenever the system calls for it, which of course is dependent on how much air is being lost due to leaks in the system.

SO, perhaps like Tim said the techs found and fixed enough leaks that the leveling system now never gets to Plan B.

Does your coach still maintain level, even without the aux compressor running?  If so, you are probably good to go.

If you want to check the operation of the aux compressor, it is easy to do.  Open the water drains on your air tanks, and bleed the air pressure off your main air system down to 40-50 psi.  Close the drain valves.  Using the HWH control panel, dump the pressure in your air bags so the coach drops down to the mechanical stops.  Then push the "RAISE" button on the HWH panel.  You should hear the HWH aux compressor run as it tries to pressurize the air bags and raise the coach.  If it runs, it is working correctly.  If it doesn't, you'll need to figure out why not.

Note:  I don't have slides.  If you have slides, the compressor test I have suggested may be compromised.  I think the aux compressor also tries to keep the slide seals inflated, so not sure how that will affect my little test procedure.  Some other owners with slides may know?
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
"Nature abhors a vacuum"

Re: Thomas Model TA-4101-12vdc Auxiliary Compressor Question

Reply #4 –
Thank You All for the Great Feedback!!!!!

Good news, the Auxiliary Air Compressor came on this morning, so I think everything is OK.  When the old engine air dryer filter was removed the seal on it was all twisted and wrinkled, so I'm thinking it may have had a slow leak.  When the coach was serviced I was there during the entire time, and there were no know air leaks and no found air leaks.

I guess I just worry too much!!!!

Thanks Again

John

Re: Thomas Model TA-4101-12vdc Auxiliary Compressor Question

Reply #5 –
turn the slide key to on so that the manifold emptys.. compressor should come on after a few min.. At least on mine it does

Re: Thomas Model TA-4101-12vdc Auxiliary Compressor Question

Reply #6 –
Glad to hear it is working normally.
Opening the drain valve for the slide air tank (located in front of the front tire driver's side on ours) should cause the 12 compressor to come on quickly.
Dick
Dick, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V