low air buzzer only goes off when the pressure go to 120psi

[sgosine477]

I recently changed the compressor and air governor on a 2007 mack granite cv713. When I start it up the low air warning buzzer, engine shutdown, and the lightening bolt symbol, stay on until the pressure go to 120 psi. then they go off. after the system work great and have no problems throughout the work day until the startup the next day. Need help.

[marvgarr]

maybe a piece of junk got hung up in the low air pressure switch thats what turns the light off are all the tanks 120 psi both primary and secondary might not have air getting to them throught the wet tank bad check valve

[rsb502]

if the alarm doesnt go off during the day as you use the brakes then sounds like the air supply from the secondary tank to the switch is coming up slower than the primary air tank so the alarm stays on longer, you should have a split guage make sure one needle isnt low till the alarm goes off, if not there may be an air leak on the accesory side of the secondary reservoir ther will be several 1/4 in lines d=coming off and heading to the dash one of those supplys the air for the guage and alarm