[Deper10]

As @"rheavn" would tell anyone, finding and fixing air leaks is not easy. Unlike electrical problems where we can measure at many points in a system, we are blind to what is really going on other than losing air pressure somewhere.

So we quite often have to "break into" the air system plumbing to determine where the problem lies. Many of us have built or collected a small assortment of air line fittings, gauges, and valves to make this a routine exercise.

The methodical approach of isolating and testing works. The random replacement of fittings, valves, and cylinders is expensive and does not produce satisfying results.

That being said there are a few areas that commonly cause air leaks of consequence. The electric valves that operate the dump valves, a hole in a slide seal, the bode door system, connections at the air ride seat, and the microphor potties are quick places to check.

If you haven't you might want to study this thread    http://newellgurus.com/showthread.php?tid=2690 and this one  http://newellgurus.com/showthread.php?tid=2677&page=2

And the best one of all  " @rheavn can you find your most excellent thread on the system and the air leak isolators? I couldn't find it in a quick search this morn."

That thread should be a sticky at the top of air systems category.

Richard
Again, Thank You very much for the advice and links. Oddly, before we picked the coach up, it had both slide seals replaced by Newell, the dump valve replaced as well as a couple of other air leaks repaired at the small air tank and filter by Motor Homes of Texas and was signed off by there tech as air system working properly and holding pressure. Because of them working on it, we did not think this would be an issue, but I guess we thought wrong. I did check the 120 compressor and it does not seem to pumping proper pressure, will put the gauge on it tomorrow. 
Thanks

Dario and Andrea Perini
#581

[Deper10]

Ok, first you have a big leak. A leak so big that the 120V or 12V output will not overcome it. Also, with a leak that big, both of the little compressors may have worn themselves out trying to keep up.

Second, you are exactly right about turning on the key. When you turn on the key it opens the travel solenoids to the airbags. They usually will take about 90 psi to "float" the coach. If the system pressure is less than the pressure in the airbags, then air will flow from the airbags through the travel solenoids, through the height control valves and into the system.

Start by piping the 120V compressor into a deadhead with a gauge. Determine if the pump is actually capable of building pressure.
On the 12V compressor, confirm that you have 12V power on the pressure control switch at the pump. The switch is commonly referred to as the well pump switch. It is usuall a grey box about 2 by 3 inches. Wires will originate in that switch and go directly to the pump to turn it on and off.  Start the diagnosis by determing if the swtich has power.

Well I installed a pressure gauge directly into the exhaust of the 120 compressor, turned it on and absolutely 0 pressure. The pump comes on and sounds great but nothing. It is a Thomas model 2688TE44/38. I have priced a new one at 580.00 and found a rebuild kit for 300.00 but want to know what your thoughts are.
Again, thanks for all of our advice as well as all the other Gurus out there.

Dario Perini
#581  2001 45'

[ron skeen]

Ok, first you have a big leak. A leak so big that the 120V or 12V output will not overcome it. Also, with a leak that big, both of the little compressors may have worn themselves out trying to keep up.

Second, you are exactly right about turning on the key. When you turn on the key it opens the travel solenoids to the airbags. They usually will take about 90 psi to "float" the coach. If the system pressure is less than the pressure in the airbags, then air will flow from the airbags through the travel solenoids, through the height control valves and into the system.

Start by piping the 120V compressor into a deadhead with a gauge. Determine if the pump is actually capable of building pressure.
On the 12V compressor, confirm that you have 12V power on the pressure control switch at the pump. The switch is commonly referred to as the well pump switch. It is usuall a grey box about 2 by 3 inches. Wires will originate in that switch and go directly to the pump to turn it on and off.  Start the diagnosis by determing if the swtich has power.

Well I installed a pressure gauge directly into the exhaust of the 120 compressor, turned it on and absolutely 0 pressure. The pump comes on and sounds great but nothing. It is a Thomas model 2688TE44/38. I have priced a new one at 580.00 and found a rebuild kit for 300.00 but want to know what your thoughts are.
Again, thanks for all of our advice as well as all the other Gurus out there.

Dario Perini
#581  2001 45'

Definitely buy a new one

[ccjohnson]

If you buy a new one from Grainger, definitely get the extended warranty. I have replaced a couple of the Gast compressors on our coach with Grainger warranty replacements. They are great, pretty much exchange there or once in a while just "scrap in field". Not a lot of questions or hassle.