This heater box installation was done on a Kenworth T800.  Every truck is different, but these instructions will assist you to remove and install your Kenworth heater box for the following model of trucks.

  • W900
  • T800
  • T600
  • T660
  • T300
  • T370

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Step 1: – Remove the (4) 10mm bolts from the heater box cover.

Remove Fan Cover

Step 2: – Remove the blower cover.

Step 2 - Remove cover

Step 3: – Unhook the blower motor from the wiring harness.

Step 3

Step 4: – Remove the (2) 8mm nuts from the freeze switch.

Step 4

Step 5: – Remove the (3) Philips screws from the recirculation door actuator. (If your truck has an air-operated actuator this step will look slightly different.)

Step 5

Step 6 – Remove the baffle plate.

Step 6 - Remove baffle plate.

Step 7 – Remove the two coolant lines attached to the heater core. Use hose clamps or hose clamp pliers to prevent loss of coolant.

Step 7 - Remove the coolant lines
Hose clamps
Step 8 – Remove the bracket that attaches the mixing valve cable to the heater box.
Step 8 - Remove the bracket that holds the mixing valve cable.ket that
Step 9 – Remove all remaining parts from the outside of the heater box.
Step 9 - Remove all other attached parts from heater box.
Step 10 – Remove the lower cover.
Step 10 Remove the lower cover.
Step 11 – Remove the evap coil and heater core.
Step 12 – Grind off the top two mounting bolts.
Step 13 – Begin removing the interior. In this T800, we removed (3) Phillips head screws from the passenger side kick panel.

Step 14 – On this T800, there were 4 caps that hid 4 Phillips head screws (Two on each side of the console). Remove these screws and unhook the cigarette lighter to remove the center console.

Remove cigarette lighter

Step 15 – Remove the (2) 13mm nuts and the (1) 13mm bolt that attaches the heater box to the firewall.

Step 16 – Remove the (2) nuts from the air intake shroud. Then remove the box.

Remove the two bolts from air intake shroud

Next, we will be preparing the new Shoreline heater box for installation.

You have a couple of options with this. You can either block off the fresh air intake or remove the fresh air intake from the old box and then attach it to the new Shoreline Box.

Step 17: Drill out the rivets that attach your fresh air intake to the old heater box.


Drill out rivets

Step 18: Attach the fresh air intake using the supplied rivets.

Attach rivets
Installing rivets

Step 19: Install Gasket for fresh air intake.

If your heater box did not come with the gasket set installed, you can watch this video to complete those steps.

Install Gasket
Set gasket in place

Step 20: Begin to install the new heater box

Line up the two bolts on the heater box with the two holes on the firewall.

(We’ve been asked a lot about the installation of the top two bolts. Here’s a quick video showing that process.)

Install Box

Step 21: Bolt down heater box

Use the two supplied nuts and one bolt to mount the heater box into place.


Step 22: Reattach air intake to the side of the truck.

Re-attach fresh air intake

Step 23: Install heater core.

Install heater core
Install heater core

Step 24: Install evaporator coil.

Install evaporator

Step 25: Install lower cover.

Install lower cover

Step 26: Install the baffle plate.

You may find that it is easier to remove the blower motor and then re-install it onto the baffle plate after setting the baffle plate into place.

Install baffle plate
mounting tab

Step 27: Install blower motor.

Attach blower motor wiring and remount the blower motor to the baffle plate.

reinstall blower motor

Step 28: Install blower motor cover.

Use the 4 bolts to attach the cover. After this is done, re-attach hoses and any other accessories that were original attached to your box.

Install cover
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