M939 5 Ton Emergency Air Brake Release Pressure Switch

[simp5782]

Thank you, any suggestions on whyits not bulding air i checked the dryer its not open.

Start with basics. Make sure all your drain ports are closed. If so. Ensure both valves on the wet tank are open. One is on the front, one is on the top side. Those are primary and secondary valves. They can get closed if they are on their way out. If they are Open, Remove the line coming from the drivers frame rail into the air dryer. If air is present, forceful air, then check at the hose going INTO the wet tank. and see if you have air there. If you have No air coming from the frame rail into the air dryer then you need to remove the little line off the passengers side of the air dryer and blow back thru it. This signal wire can have the unloader in the compressor turned off. If Yes then you need to check to ensure the amount of pressure there is. So you will have to rig up a gauge to be able to check air in the line.

Where in Mississippi are you?

 

[simp5782]

I will add that a stuck open spring brake override valve could cause no air pressure if it had a bad spring brake diaphragm as well since it is allowing air to go right to them

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[Ssgt cornbread]

Thank you for your help im in gulfport

 

[Ssgt cornbread]

Everything was working perfect until that button was pressed

 

[simp5782]

Everything was working perfect until that button was pressed

Block the port off. Or i can send you a valve. You may have a bad spring brake diaphragm then.

 

[Ssgt cornbread]

That would be great mailing address is 136 chalmers dr biloxi ms 39530

 

[Ssgt cornbread]

Thank you for your help. I believe The whole issue is my air dryer air and going in but not out. If the air dryer is still acting up I was told to check the governor

 

[simp5782]

Thank you for your help. I believe The whole issue is my air dryer air and going in but not out. If the air dryer is still acting up I was told to check the governor

Take the little line off on the passengers side of the dryer that goes up to the frame rail. and put an air gun to it and blow back thru it to ensure it isn't stopped up. This goes to the governor. Usually If your getting air to from your compressor to your dryer then your governor is working since the compressor is on. However you need to check your "air pressure" at the dryer. It can be putting out air but not enough to charge the system.

 

[Ssgt cornbread]

Not sure the pressure but at the compressor it was pumping same amount and sound was at the dryer but again nothing coming out I took off filter alot of goo inside.

 

[Ssgt cornbread]

Do you know if the m944a1 is compatible with m939

 

[simp5782]

for air dryer parts? Mostly any air dryer for any truck can be adapted over to another one. It is just a simple issue of mounting and fittings.