Last year, I purchased a 2001 1500 QuadCab with 120k miles that was suffering from a severe bout of deferred maintenance. After addressing the engine and steering pump issues, I took it to a local independent repair shop for HVAC work: new evaporator, heater core “while you’re at it”, Heater Treater coupling for the blend door, recharge the system. Then it was topped off with a dashboard rebuild and new dash pad and instrument bezel. HVAC working great.

This year, AC is chillin’ but it’s mostly chillin’ my feet, and very little air is coming through the dash vents. I’m guessing the actuator for controlling where the air goes is defective. No problem, I’ll just tape off the floor vents so air is forced through the dash vents.

Problem. Very hot air is coming out around the heater core, blowing against the bottom of the dash structure, spilling out past the missing glovebox door and warming the cabin as fast as the AC can cool it. I can’t tell from the drawings in the shop manual, but it appears from looking at the HVAC housing

HVAC housing with top of heater core above edge. Hot air coming from side, flowing up toward dash structure.
that once upon a time there was a cover of some sort over the heater core to contain the air flow. If there was a cover, I don’t know if it went AWOL when the HC was replaced by previous owner #1 or #2, or when local shop did repairs for owner #4 – me.

Anyone had this problem, and how did you fix it? Besides bypassing the heater core for the summer.

Thank you

 

Were the door seals replaced in the box when it was opened up for the core replacement?

 

I have no idea. HC was replaced by previous owner #1 or #2, the solid lines were cut and hoses spliced in to make the lines flexible, I'll assume the dash assembly was not fully removed to do it, so probably no the seals weren't replaced.
The dash assembly was removed when the HC and evaporator was replaced in June 2022. Seals? Shop didn't put back what wasn't there or old ones were so damaged they just pulled them off.
What do the seals look like? Is there something like foam I can push down the sides that won't melt from the heat? Was there originally a cover or hood over the top of the HC to keep heat from radiating back into the interior?
Thanks for your assistance.

Joe Truckster

 

Door seal from a big-box store.

 

Latest: When I talked to the shop that did the work in June 2022, one of the mechanics suggested getting a coolant shut-off valve, NAPA $15 (his better-than-shop-manual drawings don't show a cover). Installed it a few days later in place of the hose coupling between the two molded coolant hoses between the intake manifold and the heater core on the passenger side hose. No hot water to HC.
Today, I removed the airbag sensor to see what's behind it. The actuator that moves the floor/panel door is functioning but the plastic bellcrank or lever that attaches to the door and actuator rod has come off. It doesn't appear to have any itty-bitty pieces broken, but it won't stay attached to the rod. After more than two hours of fussing, cussing, sweating and multiple trips to the toolbox for instruments to go where fingers can't, I taped over the floor vents again. Much more cold air out the panel vents, no hot air from around HC. I hate doing this kind of redneck engineering, but removing the entire instrument panel assembly isn't worth the effort required. Besides, the dash will probably implode into hundreds of brittle plastic shards.