Country Coach Aux Air Compressor

[Denny]

I have a Thomas auxiliary air compressor mounted in the bay behind the front bumper. When it is building pressure, air is escaping from the check valve located directly above the green ASCO switch. Once the air is built up and the compressor stops, the escaping air stops almost immediately. It builds good pressure but seems to take longer than I think it should.

None of my other compressors do this but they also do not have this ASCO switch which is wired to the pressure switch. CC changed the configuration on the Thomas air compressor in that the ASCO switch was added and the tube from the intake pipe to the pressure switch was eliminated.

I am thinking of replacing both the ASCO switch and the check valve but wanted some info as to whether this is correct or not. If this air releasing is normal, then I will not replace them since everything else is working fine.

[dale farley]

Denny, Is this the same check valve that I replaced on my compressor? I made some posts about it when mine was leaking. This is a link to the post. http://forum.prevostownersgroup.com/showthread.php?t=2780 I ordered the parts from Thomas, but they shipped the wrong items. I went to a local "Air Products" shop and got the replacement valve.

[Joe Cannarozzi]

Denny is the aux. air pressure holding better?

[Denny]

Joe - The aux pressure is holding much better!

Dale - That looks like the check valve I am talking about. Yours looks like the drawing in the Thomas manual but mine has been changed. There is a ASCO switch between the tank and the check valve. I'm going to get a new check valve locally rather than contact Thomas. Who knows what was changed on my compressor and they would send me the wrong part.

These ASCO switches are used a lot by CC. There are a few in the bay under the driver seat.

Thanks for the help!

[JIM KELLER]

Denny, I too have replaced the check valve on my Thomas Compressor. At first I was going to replace the compressor and after some research I determined the Thomas to be a great compressor.

Replace the valve and keep the compressor.

How are you doing up there ? Are you keeping warm ?

[Jon Wehrenberg]

Denny,

When you talk about an ASCO switch is it possible you are referring to a solenoid valve?

[Denny]

Oh Great One, I stand corrected. Since it is made by Automatic Switch Company I was referring to it as a switch. :)

[Jon Wehrenberg]

Denny,

If that is a solenoid valve, and it turns out to be defective (leaking or not functioning) they are fairly generic and easily obtained. Places like WW Grainger would have them in every variation you could require. A soleniod valve could also be very effectively used as a check valve, opening only when the compressor is powered. Just be sure to orient it properly with respect to which way you want it to hold pressure.

[Denny]

Jon,
Thanks for your response. I don't understand why I have a check valve and a solenoid valve. The picture that Dale posted of his Thomas compressor does not have the ASCO solenoid valve but has a check valve. On mine, they are both mounted in line with the solenoid valve closest to the tank. The ASCO valve is wired to the pressure switch making it electrical while the check valve is mechanical, I think. To me this is a duplication of parts and one or the other would be sufficient for proper operation of the compressor.

Grainger does carry the ASCO solenoid valve. This valve is in the closed position until the pressure switch calls for the solenoid valve to open when the compressor turns on. I'm going to bench test the solenoid valve to be sure it is working properly and then reinstall it along with a new tube running from the head to the tank. I will try this, eliminating the check valve, and see if the compressor functions properly.

[JIM KELLER]

Denny, On my Bus the solenoid valve is used for the remote function of draining water from the tank. I think.

[Jon Wehrenberg]

I think we can find numerous applications for solenoid valves in our coaches, limited only by how creative we choose to be.

I agree with Denny's analysis. The valve just has to be oriented so it closes against the flow in the proper direction because most use line pressure to create a positive seal, and tend to leak if pressure is applied in the opposite direction. That is one reason why Norgren spool valves are used in the suspension because they seal equally well regardless of which direction the pressure comes from.

[Denny]

Jim
My compressor has a solenoid valve that drains the water from the tank also The switch is located in the first bay, passenger side on the forward wall. That was not working so I purchased a replacement from Grainger; it is working now.

I pickup a new check valve this pm and will try to install everything this evening.

[truk4u]

That solenoid valve can be taken apart and cleaned. I did Jamies and also Rogers with good success. The valve gets all gunked up by years or months of non use.

Sorry Denny, I would have suggested this, but I thought you were talking about a different valve.:(

[rfoster]

I must acknowledge my appreciation to Truk and Mr. Toolman Jim Keller for their expert extraction of a ball point pen (that belonged to yours truly) from deep down in the fan of the front dash heat/air blower of my bus.

I don't know if anyone else has ever experienced this, but the pen can make quite a racket as the blower speed increases.

And it ain't no small task! and there ain't room in the step well for three guys, two yes, three no.

Morale of this story: Don't lay a pen on the dash, or have The Toolman and Truckster near by.

[gmcbuffalo]

I bought an air compressor out of a old RV to put in my bus and there was a solenoid like described here. The only thing I could figure out was that the switch was to reduce any head pressure that pressure regulatory would see that may prevent it from starting. Is this solenoid electrical switch hooked up to a device that may need air, i.e. toilet or pocket door, so that when the device calls for air it trips the solenoid which events air and the compressor see low air pressor and turns on.
GRegM