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Wayne, Journeyman
Category: Heavy Equipment
Satisfied Customers: 9659
Experience:  34 years experiance as engine rebuild and problems.Thermo-King repair and trouble shooting.
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Freightliner..air pressure it seems the compressor or governor..heated

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I've got a 1998 freightliner fld, I live in iowa and every time it gets in the single digits and its been sitting a couple days when i go to start and it tries to build air pressure it seems the compressor or governor is frozen and stuck. I've got an air dryer on the truck that works but I don't know if theirs anything i can do to keep this from happening. the last time it happened a month ago I had enough air pressure in the system to get it to a heated shop. this time I don't so I'm gonna have to drape something over the hood and blow some heat under the engine it to get it thawed out. any ideas on how to prevent this?

wayne :

Hi I'm Wayne, I will help you with this,

wayne :

I do not know what Year, or Last Time you changed Drier, but this is not uncommon, your desiccant is getting Plugged in drier, , It has a Heat element in base, that after 8-12 minutes, it will let it function, but if it is taking this long,. Replace drier , Assume it is a AD 9

wayne :

The Drier, is going to shut off air pressure build up Back to compressor .....

wayne :

Hello you There ??

wayne :

I see you going in and out of Chat

wayne :

Do you want me to switch to to Q & A ???

wayne :

is that easier for you ...........


I have switched to Q & A,

Please respond here

Thanks, Wayne
Customer: replied 6 years ago.
I just put a new air dryer on 2 months ago. it's only like 4 degrees out and when i go to start it after its started the compressor/govener area makes a popping air sound, and it won't build air. happens everytime it sits for a couple days when its this cold. assuming i'll have to somehow get it thawed out, just trying to figure out how to prevent it.
Morning ,

OK, this sheds a little more light now.........

that popping sound you are hearing is the unloader valves in the head sticking, get your compressor, model, and P/N, go to truck parts and ask for a unloader kit

Thanks, Wayne
Customer: replied 6 years ago.
ok, how hard is to change out or how much time would it take a mechanic to do it?

Not hard at all, remove, head, (drain down coolant 1st ), clean up and install new unloaders,
Labor about 2 hours

Wayne and other Heavy Equipment Specialists are ready to help you
Customer: replied 6 years ago.
ok thanks

You are Welcome

Customer: replied 6 years ago.
one more thing, how do you drain the coolant and do I need to take the entire compressor off to to do it? thanks

At bottom of your radiator is a drain cock, just drain out about 5 gals of coolant........
(catch in a bucket to reuse )

No leave compressor, in tact, just remove air lines and coolant lines ,
Get parts 1st , so you know they have them, may have to order ....