If you see day light between the 5th wheel an trailer the king pin is on top of the jaws that's a high lock. A good thing to do is do your tug...
Starting fluid works good too.
did you change the dryer?
It's sill low on Freon static should be around 100 .
I cant remember the years but one is on the valve under the 5th wheel , one is under the frame between the air tank fuel tank & trans. on the...
I found out the had way there is a low & tall air bag for IH trucks.
Check the thermastat switch in the box by the blower motors. If it is ok check the high & low press. switches on the expansion valve.
check the ground side. the sensors use the ground to control the fan switch.
if you need to check an clear heavy truck codes you need the otc code reader about $400.00. an it will show abs codes. otc 3418.
Change the cable I have had old mack trucks do the same thing.
May be loose wheel bearings.
The intake will come off the intake manifold or air filter with a rubber hose .The outlet will go under the cab to the air tank.
Like every one said the comp. needs to cycle winter or summer. So plug it back in.
OTC 3418 hand held code reader is a good deal about $400.00. it will check an clear engine/trans. an abs .
