Attention: TDR Forum Junkies 
RSchwarzli
TDR MEMBER
A little known tidbit of info for many who are new to these trucks. The air intake for the inside HVAC (heating and AC) system gets sucked from the cowl. The air goes down the cowl, down the side channel (under the A pillar), and through a hole in the side of the passenger kick panel into your air box. There is also no filter. If you have ever parked your truck outside, this means you likely have some debris in your system. Debris means funny smells over time in your truck, less airflow, and potential rotting/rusting of the AC evaporator.
There was once a time on these boards that the first gen forum was the place to be. This part of the forum was VERY active. With the trucks getting older and fewer of them on the roads, there are fewer people here and some of the little secrets are starting to be lost. To prevent that, I am adding this so those who are new to these trucks can find this info.
Issue: Debris in heater box under passenger side of dash
Symptom: Lack of airflow, heat, or AC not as cold as a fully charged system should be
Remedy: Open box and clean out, or add access panel
Things needed: Saw, knife, RTV Gasket, flashlight, vacuum, 6” x 4” sheet of black plastic, drill and 1/4"-1/2" drill bit
Time - Will take about 20 min start to finish
Cost - Not much!
As mentioned above, leaves, pine needles, etc will fall down the cowl and be sucked into the heater box. The first blockage the foreign objects will encounter is actually the AC evaporator core itself on the inside of the box. To clean out the box without removing the heater box from under the dash, try the following steps.
1 - Using a drill bit of any size that will allow the cutting tool into the plastic, drill 4 holes one at each corner of the area to be cut open. Then using a knife, small plastics saw, etc, cut open the front of the heater box.
/webdata/photopost/data/500/DSC_3611.JPG#ad
/webdata/photopost/data/500/DSC_3612.JPG#ad
Do be mindful that the AC evaporator fins will be behind the area you will be cutting. Please note the depth of cut allowable in the following photo:
/webdata/photopost/data/500/DSC_3609.JPG#ad
/webdata/photopost/data/500/DSC_3608.JPG#ad
2 - Cut an approx 3” x 4” hole (enough for your hand and some leaves to go through) in the front of the box. Ensure the hole is cut at least 2” from the bottom of the box. As the evaporator sweats when in use (all that water that drips under a vehicle in the hot summer comes from this area), you will want to make sure that hole is high enough that even a little backed up water does not leak out the new cut hole.
3 - Once cut open, you will likely see leaves. Shine a flashlight in to get a better view of the far left side (the area it will build up in first).
4 - Once the big items are cleaned out, vacuum out any leftover debris. If all of the plastic shaving dust is not collected, it will be sucked into your AC or heater core grills.
5 - Now cut the sheet of plastic so that the corners are lightly rounded. You should find that the cut plastic will have about a 1” wider cover on each side of the hole.
6 - Apply RTV gasket to the heater box within 1” of the hole. The ideal location is about . 5” from the perimeter of the hole. Also ensure the bead of RTV is constant all the way around. This bead will act as both glue to hold the panel on as well as preventing air from being sucked in underneath the new plastic cover.
7 - Stick the plastic cover to the RTV ensuring the cover is about centered over the hole. Hold pressure on cover for about 1 min.
8 - Vacuum spilled debris and plastic shavings off of pasenger floorwell!
9 - See if you have more airflow than usual!
Here is what came out of my box.
/webdata/photopost/data/500/DSC_3588.JPG#ad
/webdata/photopost/data/500/DSC_3605.JPG#ad
And the finished product!
/webdata/photopost/data/500/P1000565.JPG#ad
There was once a time on these boards that the first gen forum was the place to be. This part of the forum was VERY active. With the trucks getting older and fewer of them on the roads, there are fewer people here and some of the little secrets are starting to be lost. To prevent that, I am adding this so those who are new to these trucks can find this info.
Issue: Debris in heater box under passenger side of dash
Symptom: Lack of airflow, heat, or AC not as cold as a fully charged system should be
Remedy: Open box and clean out, or add access panel
Things needed: Saw, knife, RTV Gasket, flashlight, vacuum, 6” x 4” sheet of black plastic, drill and 1/4"-1/2" drill bit
Time - Will take about 20 min start to finish
Cost - Not much!
As mentioned above, leaves, pine needles, etc will fall down the cowl and be sucked into the heater box. The first blockage the foreign objects will encounter is actually the AC evaporator core itself on the inside of the box. To clean out the box without removing the heater box from under the dash, try the following steps.
1 - Using a drill bit of any size that will allow the cutting tool into the plastic, drill 4 holes one at each corner of the area to be cut open. Then using a knife, small plastics saw, etc, cut open the front of the heater box.
/webdata/photopost/data/500/DSC_3611.JPG#ad
/webdata/photopost/data/500/DSC_3612.JPG#ad
Do be mindful that the AC evaporator fins will be behind the area you will be cutting. Please note the depth of cut allowable in the following photo:
/webdata/photopost/data/500/DSC_3609.JPG#ad
/webdata/photopost/data/500/DSC_3608.JPG#ad
2 - Cut an approx 3” x 4” hole (enough for your hand and some leaves to go through) in the front of the box. Ensure the hole is cut at least 2” from the bottom of the box. As the evaporator sweats when in use (all that water that drips under a vehicle in the hot summer comes from this area), you will want to make sure that hole is high enough that even a little backed up water does not leak out the new cut hole.
3 - Once cut open, you will likely see leaves. Shine a flashlight in to get a better view of the far left side (the area it will build up in first).
4 - Once the big items are cleaned out, vacuum out any leftover debris. If all of the plastic shaving dust is not collected, it will be sucked into your AC or heater core grills.
5 - Now cut the sheet of plastic so that the corners are lightly rounded. You should find that the cut plastic will have about a 1” wider cover on each side of the hole.
6 - Apply RTV gasket to the heater box within 1” of the hole. The ideal location is about . 5” from the perimeter of the hole. Also ensure the bead of RTV is constant all the way around. This bead will act as both glue to hold the panel on as well as preventing air from being sucked in underneath the new plastic cover.
7 - Stick the plastic cover to the RTV ensuring the cover is about centered over the hole. Hold pressure on cover for about 1 min.
8 - Vacuum spilled debris and plastic shavings off of pasenger floorwell!
9 - See if you have more airflow than usual!
Here is what came out of my box.
/webdata/photopost/data/500/DSC_3588.JPG#ad
/webdata/photopost/data/500/DSC_3605.JPG#ad
And the finished product!
/webdata/photopost/data/500/P1000565.JPG#ad
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