I replaced the wabco air dryer a few weeks ago, now it making a noise sounds like a horn blowing in the cab. Is there anything I could have possibly missed. thanks in advance
Not sure if an 07 has it but there is a plastic junction of air lines behind the batteries on the frame rail.
I have had 2 different Volvos leaking from that and doing crazy things..
check for air leaks and from the bottom of the air dryer where the little muffler is unscrew it chuck it away and see if its leaking, or its air leaking somewhere else