Kenworth T2000 HVAC

[Chad Heiser]

I am having an issue with my HVAC system in my 2000 T2000. At first I thought it was my AC, but have since ruled that out. The AC blows cold and has no leaks and has been tested by a shop. My issue is either with the controls (less likely) or with the blend doors (more likely). Once the motor warms up the heater overpowers the AC and blows hot. I have turned off the heater hoses leading to the HVAC system and now the AC works great, but I have no heater (luckily it is summer).

 

I have torn apart the dash multiple times on my T2 and I know there are no HVAC parts other than ducts in there. It appears all the HVAC components are on the engine side of the firewall just below the windshield. Has anyone ever torn into a T2000 HVAC system? Do any of you have any schematics or tips on dealing with this issue. I'm debating doing it myself or having a shop do it. I'm thinking it is either a wiring problem or an electrical motor of some type that has got the blend doors stuck open to heat.

 

My AC controls in the dash mostly work. The fan control and A/C switch work as expected. The recirculate and vent switches don't appear to be doing anything - like the motor that controls which vents are selected/turned off has quit.

 

Any input is appreciated.

[noteven]

Hi Chad are you going to work on this repair yourself if possible?

[Chad Heiser]

Hi Chad are you going to work on this repair yourself if possible?

I might give it a shot. I'm leaving next Friday for a month long trip and won't have time to tackle it until I return home, but I would like to gather some information in the mean time to determine if it is something I can handle or not. I will definitely discuss it with some of the WCR attendees that should have some experience with such repairs to help me make my decision.

[Ronbo]

Kenworth dealer can print you out pictures. Your blend door has to be in defrost when removing the assembly from firewall. I haven't done it yet. Take a lot of pictures if you do. I believe I have a stick blend door for the dash vents. From what I have read dirt can get in there and bind them up. It looks like I may be able to get to it by pulling out the ad coils and the heater core. It looks like they just slide out after some removal of panels. Let me know

[HERO Maker]

Chad, I found that one of my cables was not anchored down correctly and would just slip out when a little pressure was applied. I was in and out of there 3 times before discovering that.

[Ronbo]

The t2000 has motors that move the doors. They are on top

[Chad Heiser]

Kenworth dealer can print you out pictures. Your blend door has to be in defrost when removing the assembly from firewall. I haven't done it yet. Take a lot of pictures if you do. I believe I have a stick blend door for the dash vents. From what I have read dirt can get in there and bind them up. It looks like I may be able to get to it by pulling out the ad coils and the heater core. It looks like they just slide out after some removal of panels. Let me know

Thanks for the information. I knew the control had to be set to defrost before removing the assembly. There is a big warning sticker on the outside of it telling me that. I'm hoping to track down a schematic or an exploded parts view of it to give me a better idea how it is put together and what might be causing my issue.

[dennisvr]

Chad, have you checked the heater shut off valve? There pretty easy to check, after the coolant heats up check the temp of the hoses the return should not be hot, if so its bad. Let me know if your having problems getting info on your truck, I should be able to get what you need from work, I work at the KW dealership outside of Stockton.

[Chad Heiser]

Chad, have you checked the heater shut off valve? There pretty easy to check, after the coolant heats up check the temp of the hoses the return should not be hot, if so its bad. Let me know if your having problems getting info on your truck, I should be able to get what you need from work, I work at the KW dealership outside of Stockton.

Thanks for the offer. I will check out the heater shut off valve when I get a chance.

[Scrap]

Its one of those things you just have to dig in. It is super easy. Dig about a foot of stuff out of its way, undo the firewall bolts, pull out some to undo connectors, and the whole thing slides back and out. Door motors, fan, filter, and coils are pretty self explanatory when it is opened up. If you redid your AC lines with OEM length then the whole thing should flop down to a table right next to the front wheel without evacuating. Or you can also overhaul it up on top of the engine. Its worth trying before suffering through a month with it not working.

[Chad Heiser]

Thanks for the input Scrap. It looked like it should be fairly straightforward. I will most likely tear into it myself, but it will have to wait until I get back. I only have one day off work between now and when we leave and that day is already pretty full with other scheduled chores.

 

Luckily the AC works good and as long as I leave the heater hoses turned off from the motor the heater doesn't overpower the AC. It is a southern, summer trip so no heat shouldn't be a big issue. If it does by chance get cold, I'll just turn on the heated seats and put a jacket on

 

I would like to get a diagram of the system if someone has access to one to make things a little easier though.

[Radman]

Chad,

I think I have some data on the system and will share it with you when I am back in town next week.

 

I completely removed my system as Scrap described for a thorough cleaning and service. It was simple and done without surprises.

 

One thing I recal was you should have the selector in a specific setting (full defrost ?) before dropping the assembly from the firewall. That is the piece I can't remember...

 

More to follow,

[Chad Heiser]

Chad,

I think I have some data on the system and will share it with you when I am back in town next week.

I completely removed my system as Scrap described for a thorough cleaning and service. It was simple and done without surprises.

One thing I recal was you should have the selector in a specific setting (full defrost ?) before dropping the assembly from the firewall. That is the piece I can't remember...

More to follow,

Thanks, I appreciate any documentation you can provide.

[tyates007]

Chad I just replaced pretty much the whole hvac box in my truck. I had it done due to work schedule. All of my blend doors were broke as well as some other stuff. Parts were not cheap but easy to get. It still is not working exactly as it should on our last trip but think I got that sorted out now. The shop had all the diagrams and such downloaded and in the truck when I picked it up. Let me see if I still have them and if I do I'll send to you.

[Ronbo]

If possible could you send them to me too? I need to repair mine as well.

[Darryl&Rita]

Or, just post them here, for inclusion in the Resource Guide. Sheesh.

[Chad Heiser]

Chad I just replaced pretty much the whole hvac box in my truck. I had it done due to work schedule. All of my blend doors were broke as well as some other stuff. Parts were not cheap but easy to get. It still is not working exactly as it should on our last trip but think I got that sorted out now. The shop had all the diagrams and such downloaded and in the truck when I picked it up. Let me see if I still have them and if I do I'll send to you.

That would be great. Thanks.

[Mtin]

I've got a '97 t2 I'm having issues with my heater it works well in my sleeper but not up in the cab all of a sudden it works when I'm parked then I get going and it quits and nothing but cold air comes out any help is appreciated thanks In advance!

[Chad Heiser]

 

3 hours ago, Mtin said:

I've got a '97 t2 I'm having issues with my heater it works well in my sleeper but not up in the cab all of a sudden it works when I'm parked then I get going and it quits and nothing but cold air comes out any help is appreciated thanks In advance!

It turned out my issue with my heater was that several of the blend doors and blend door servos were broken or inoperative.  I ended up having my local dealer do the work on it.  Once all the doors and servos were replaced, everything went back to working normally up front.  It wasn’t a very difficult job and the parts were easily identified and replaced.  Once the unit was removed, it was pretty obvious what was broken.

The sleeper system works from a separate control and core, so it could easily continue to function properly when the front is not working.