air problem

hello anybody out here..need help i had a issue with my truck ..first my secondary air tank not building air fast enough.second my air bag seats,the horn,and my shifter does not work till it reaches 110 psi.i cant shift to 6xt. gear ..had a mechanic looked at it and said it was the air dryer,he replaced it and,wich it wasnt the problem cause it was doing the same thing so i dropped it at the freightliner dealership in dearborn ,mi. so they can figure out the problem ,they have my truck for the past week and half.they made me buy a new air dryewr cause the also believe it was that after i told them i already had bought it.but i did so now i called them and thewy told me theyre calling bendix..????? for wht i dont know..they cant figure why my truck is doing that..i been out of work for 2 weeks now .dont know wht to do..anyone had the same problem or is there any mechanic out here that might know wht the hell is wrong..its hard to belive they cant resolve these problem..oh almost forgot they also replace the unloader valve in the compressor..please help..

my truck has a detroit diesel 14.lt
freightliner 2007 columbia

 

Thanks guys im just giving them till tomorrow .im frustrated I dont tgink its a mayor fix..but yes after tomorrow ill be looking at a different shop ..u figure its a freightliner dealer..appreciate..the come bak

 

Thanks for the response

 

Hey man ..they call me these morning ..the air dryer I got from fleet pride truck and parts ..gave me the wrong part.the look the same but the internal check valve are different ,the one they gave me.opens up at 110 psi..mine for freightliner should open at 55 to 60.when they pull the second air dryer the looked at the numbers dont match..800383 part number for freightliner .. the other one is 801266..wich is for kentworth or peterbilt ..now I dont know if ill get my money bak for the other one.but at least they found thr problem..late but they found it..hopefully i can get rolling early next week...have a god weeekend everyone ..thanks god bless

 

Thanks for the reply..thats wht tge dealer noticed later,when we got the air dryer look the same but we didnt match numbers on dryer so when they called biendo,thats when they told them the settings are different from my freightliner to kw. Or peterbilt..but tge only thing i dont like its that it spits out close to 150 psi .easily i know it spits out at 135 0r 140..they told.me its normal so Ill go with that..