scania 114c slow to build air

[KRIZ]

Scania 114c replaced air compressor 20000 klms old genuine unit.
The truck has been slow to build air for a while .
Spent a lot of time chasing leaks and repairing , im happy now the system is sealed up but the build up time is slow as just to get the interlock off at the first run is a coffee and 4 walks around the yard.
Drier cartridge changed still slow. The unit doesnt seem to snap off the drier dump like other truck brands we have just lets out a huff through the silencer on the dump line ( removed and cleaned nothing too nasty) .
ive had shop air on the flex line when i replaced the compressor and it didnt seem to take long to get up to release pressure.
Any known tricks please leave a reply.
Cheers

 

[Truck Shop]

Did you check the governor and governor signal lines?

 

[KRIZ]

Yes TS it has a single governor line from the drier head to the compressor its not crimped or blocked.
Im thinking the drier head its self may be the issue but its hard to think the compressor could be in a reduced state of output from the governor. The drier is integral (wabco i believe) not an addon unit on the scania. Ill have to strip out the drier head and reseal it to be sure. The scania guys havent had the issue on this model that they can inform me of even though theres a few of them banging around within 500 klms of us. More truck wash and looking for leaks even though im sure we have nailed them out of the picture.
Itll be something in the control system or possibly a dudd compressor non return somewhere as it had low air after sitting overnight last night.
Cheers for the reply.

 

[Truck Shop]

Sounds like unloader is leaking in compressor, bypass the air dryer and run straight to wet tank first. Not a
fan of Wabco dryers