bismic: Any idea where I would locate that valve? I'm having a hard time even finding the heater hoses. It's a mess of hoses under the hood!

 

Isn't that the truth - it is located close to the firewall on the passenger side ... between the turbo and the oil fill tube (next to the "hard to find" MAP sensor). At least this is where it is on my 2006.

 

Ok great, I'll see what I can find when I get home later. It will be dark but I'll still give it a shot along with the other checks I need to make. Thanks!! Jim.

 

Todays update:

Checked coolant and it is at the required level. No signs of any leaks or coolant loss.

Found the heater hose control valve. It works off of vacuum. In the off position it retracts so I'm guessing that's closing the valve. In any other position it extends which I would guess means that it allows coolant to flow through it. It is working and does cycle. There is no impact on this valve when I adjust the temperature dial in the cab.

Found the electric control module located behind the glove box. Unpluged and plugged it back in. There doesn't seem to be any change from doing that.

Checked the only operating rod I could find behind the glove box. When I change the output selector from off to vent or floor it does change positions. The air flow exits the correct vent setting. ie when set to Defrost air blows out the defrost vents, when set to vent air blows out the vents etc..

I think that was everything suggested by everyone, at least the things I could do at night in a parking lot. So far nothing seems to help.

A couple questions for anybody who might know:

Is there a "blend" door of some sort that might not be working? If so can you tell where it's located or how it's controlled? Perhaps there is a cable or vacuum line loose?

Is it possible that an air bubble in the heater hose or heating system could be blocking the hot water flow? If so any idea how I could "burp" it?

Thanks again everyone for all your help! I'll be really getting into it on sunday when the rain stops. So much for the Super Bowl party! Jim.

 

Do you have no heat at all or intermittent? In cold weather my 03 will go cold at a stop light, I installed a radiator block, problem solved.

 

For a short time it was intermittent but now it is only cold air. No heat at all in the cab. I'm not sure what a radiator block is but the engine heats up to normal temp just fine. I'm thinking my problem now must lie inside the cab.

 

A radiator block is something that covers the front grille to restrict air flow. It allows for the truck to get to operating temp quicker and maintain it in cold temps.

 

Sounds like the actuator on top of the heater box may be the problem, located right behind your glove box. Check that to see if it is operating the blend door.

 

That's right along the lines I was thinking. I looked it up on the Alldata web site and found where it's located. So when it stops raining I'll check that out. Looks like that's how I'll spend my superbowl sunday. Oh well, need heat if I'm going to Utah next week!

 

no one has mentioned the oil cooler or egr cooler being plugged up.

maybe the heater core isn't even getting coolant flowing thru it.

 

Any idea how I would test for that? Temps seem normal and oil pressure seems normal.

 

Good thinking. Not real common, but it does happen.

 

Disconnect the heater hoses and flow air or water through them (or at least try to).

69cj is a BIG advocate of VC-9 cooling system cleaner. I would have to agree with him after reading MANY posts on plugged cooling system. If the heater core is pluged, I would tend to believe that the oil cooler is also. The latest flash that will throw a code when the oil cooler is plugged is a fantastic "upgrade".

 

Sounds like a big project, that will have to wait until I'm able to do that. Maybe sunday I'll give it a try. I remember reading that I need a special tool to disconnect the heater hose so I'll need to find one of those. Unless you know an easier way?

So tonight I'll see if I can locate the blend controller and see if that's working. If it is then I guess it's on to check for flow in the hoses themselves. Yikes! Maybe I better just stay here in kalifornia where it's warm! lol!

 

Jim - you can swing by and pick up a few blankets...I've got some extras

Seriously though...if you don't want to fool with that method you might want to consider giving Bud at OC diesel shop in Mission Viejo a call to see if tomorrow he can hook his laptop up to it and you can take it out for a little cruise, and before long he'll be able to tell you if your oil cooler is plugged up or not. He's a great guy....he won't stick it to you.