Truck Heater Problems

[Swamp Dawg]

Hi All,

This is a question for any peeps out there that drive or have driven a Century Class Freighliner. I just started driving this truck for a fella that leases the truck to Acme out of Houma, LA. I love the truck. (Beats the hell out of the mini-floats I had been driving) Anyway, the only problem with the truck is that I can't get any heat. We checked the line that runs from the radiator and (according to the owner) supplies the heat to the truck. All the valves appear to be open and the hose is hot to the touch but the vents still blow cold air. Has anyone else out there ever come across this problem and if so, how did you solve the problem.

Thank you,

Jim

[Blind Driver]

Make sure BOTH valves are open, and you have plenty of coolant.

[Swamp Dawg]

Hey Blind Driver,

Thank you very much for the reply. We did check each valve and even though the coolant wasn't too low, we topped it off and tried again. Still no luck. From what I can see, the hose comes off a radiator hose and leads to a valve. From that valve the hose leads to a filter and from there leads back to the radiator hose through another valve. I am wondering if the filter is clogged or one of the hoses.

Thanx,

Jim

Make sure BOTH valves are open, and you have plenty of coolant.

[Trukrswyfe]

What about the selector switch. it is blowing hot air in a different vent , ie the dash?

Husband said his selector switch goes on the fritts a lot.

TW

[Uturn2001]

If it is a sleeper truck do you have heat back there?

[headborg]

blowing cold air--or no air---check the cab air filter to see if it's clogged.

does the truck have opti-idle? or the computer info center--with push the diagnostic button and see if you have any errors that read HVAC response lag or something about HVAC Controller?

how about the water temp---what's it idling at?

[kc0iv]

If it is a sleeper truck do you have heat back there?

It has been over 3 years since I've been around a truck but if I remember right there are 4 valves on a Freighliner that has a sleeper.

kc0iv

[Swamp Dawg]

Hey Y'all,

So far I have only messed with the valves that according to the owner, are responsible for providing heat to the front of the truck. I can see the the hoses and valves that are for the sleeper but have not messed with them. According to the owner, the heating/cooking to the sleeper part of the truck is temporarily "out of service".

Jim

[Swamp Dawg]

Hey Headborg,

The truck comp info readout says that there is one "fault" but I have not been able to figure out how to find out what it is. Not sure if I have to hook the chip up to a diag comp or not. Since I am fairly new I am not sure what you mean by "opti-idle" but I do have a toggle switch where I can increase or decrease the trucks idle speed. Please pardon my stupidty, I am still learning.

Jim

blowing cold air--or no air---check the cab air filter to see if it's clogged.

does the truck have opti-idle? or the computer info center--with push the diagnostic button and see if you have any errors that read HVAC response lag or something about HVAC Controller?

how about the water temp---what's it idling at?

[Swamp Dawg]

Hi Trukrswyfe,

I am getting cold air out all vents from what I can tell. I have tried defrost, feet, and straight on.

Thanx,

Jim

What about the selector switch. it is blowing hot air in a different vent , ie the dash?

Husband said his selector switch goes on the fritts a lot.

TW

[Swamp Dawg]

Hi kc0iv,

So far I have only messed with two valves. If there are four then maybe that is the problem. Now I just need to find the other two. Are the other two for providing heat for the sleeper?

Thanx,

Jim

If it is a sleeper truck do you have heat back there?

It has been over 3 years since I've been around a truck but if I remember right there are 4 valves on a Freighliner that has a sleeper.

kc0iv

[headborg]

ok, you have a row of computer buttons on the right dash panel

that should read something like this from left to right:

(blank)| temp |fuel| trip |leg |< |(down arrow) |>| set/reset| (blank)

(1) press the > button once
(2) press teh (down arrow) button 4 times or until the dash panel reads:

Diagnostic Information

(3) now press the > button again and read the Error message or it will read:

ACTIVE FAULTS
NONE

it might read something to do with HVAC controller response time then numbers ( hours, minutes, seconds) that your (heat, vent, a/c controller has failed to respond. Some time this happens with this truck when I set the opti-idle temp control back in the bunk--and all the air stops blowing completely.

other times it blows warm air when it should be blowing cold air, never had it Blow cold instead of hot? did you climb out and make sure you A/C
clutch isn't engaged and thus you're AC is overriding the Heater?

[kc0iv]

Hi kc0iv,

So far I have only messed with two valves. If there are four then maybe that is the problem. Now I just need to find the other two. Are the other two for providing heat for the sleeper?

Thanx,

Jim

If it is a sleeper truck do you have heat back there?

It has been over 3 years since I've been around a truck but if I remember right there are 4 valves on a Freighliner that has a sleeper.

kc0iv

Yes 2 are for cab heat and 2 are for the sleeper. As to where they are located I can't tell you. I simply don't remember, Sorry. Maybe someone that drives a Century Class Freighliner can tell you where each of the valves are located.

One other thing that might be your problem is blocked air filters. Reading the service manual these filters should be replaced every six months. You can download the manual at: https://secure.freightliner.com/newb...e%20Manual.pdf

Go to section 83-02 (near the bottom of the download) it discusses how to replace the different filters.

You can also download the operator's manual at: https://secure.freightliner.com/newbulletins/techmanuals/DM-MM_Web/English/Freightliner/Driver's%20Manuals/Century%20Class%20ST%20and%20Coronado%20Driver's%2 0Manual.pdf

Sorry I can't be more helpful.

kc0iv

[Swamp Dawg]

Sorry I haven't been on lately. Was on a 5 day series of runs that took me out to Odessa Texas, Bridgeport Tx, etc. Just walked in the house and popped open a beer and decided to check the board. I was damn near freezing in that cab out west. I called the owner and told him that he either gets it fixed when i get back or no more long runs. So luckily he agreed and is taking the truck in Monday to be fixed. kc0iv, even though it is going to be fixed, I still really appreciate the link to the service manual. I love reading that kind of stuff so I will know in the future. I will post what the exact problem turns out to be. Again thank you to all for your input.

Jim