HVAC System and Duct cleaning

[someotherguy]

Good post except why beat the hell out of the box to remove it? With all bolts out it should come free with just a little effort; I've removed several. If it's fighting you I would expect an overlooked fastener or two...

Richard

 

[SuperTramp]

Can anyone describe the “duckbill “ what it is, where it goes, or its purpose? A picture would be great if available. Thanks!!!


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[SuperTramp]

Schurkey, thanks for your post. I’m not aware of any air leaks due to deteriorating foam, but I will keep an eye out as it could indeed impact the truck cabin. I wasn’t able to get the black plastic box (containing the coil) discounted from below the dash, either. I’m wondering if I must approach the box from another angle or use a special tool because I removed every screw I could find which only resulted in the bottom “lid” opening on the short end facing the passenger door. This allowed me to flush the coil with water/ vinegar spray and then clean water. This was sufficient to meet my objectives at the moment. I also sprayed 3-5 ounces of Lysol in all openings where air goes in or comes out of the heat/air system. It smells a lot better where before I could not be in the cabin with the heat blowing.


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[Bear 77]

Schurkey, thanks for your post. I’m not aware of any air leaks due to deteriorating foam, but I will keep an eye out as it could indeed impact the truck cabin. I wasn’t able to get the black plastic box (containing the coil) discounted from below the dash, either. I’m wondering if I must approach the box from another angle or use a special tool because I removed every screw I could find which only resulted in the bottom “lid” opening on the short end facing the passenger door. This allowed me to flush the coil with water/ vinegar spray and then clean water. This was sufficient to meet my objectives at the moment. I also sprayed 3-5 ounces of Lysol in all openings where air goes in or comes out of the heat/air system. It smells a lot better where before I could not be in the cabin with the heat blowing.


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I believe the “duckbill” is the shape of the drain hole for the evaporator and you want to make sure it’s not clogged so you have proper drainage to outside the truck, not inside. And as far as removing the entire HVAC, not just the inside cover, IIRC, there should also be something in the engine bay that’s also holding it in place. Been awhile since I’ve done it so don’t quite remember


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[someotherguy]

Edited for accuracy after getting home and checking build pics -

There are 5 screws with a 10mm head and large integral washer, all accessed from the engine compartment side of firewall, from passenger side over to middle behind engine. Some are hidden, like by the coolant reservoir. Remove the nut holding the accumulator bracket, and the bracket itself. Comparing my 92 and 94 projects one of the screws may be a stud (holds a harness bracket) depending on year/engine type; the one towards the passenger side behind the engine. Just follow the locations indicated in the pic.

There's one more, a 10mm bolt that is accessed from inside the cab. It's hidden and you need a long extension to reach it. It's toward the driver side of the top of the evaporator core hump; you can see the other end of it poking thru on the engine side by the upper evap line connection to help you locate it.

Added some notes to a stripped firewall pic, as I mentioned you'll need to remove the coolant reservoir to see several of the screws.

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Richard

 

[SuperTramp]

Someotherguy- thank you and much appreciation for all of the details you provided myself and others!!! When you or any others get a moment, would you mind telling me where the evaporator drain hole is located?

Does anyone have experience or ideas for fabricating s cabin filter since these trucks do not have one? My thoughts are that even a modest effort would help reduce the larger particles.


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[someotherguy]

Evap drain is right next to the heater core hookups, to the passenger side of them; sticks out that same oval-shaped hole in the firewall. It's just a short black plastic spout that is supposed to have a rubber 90 degree elbow on it, though the elbow is often missing.

I think fabbing a cabin filter mod would be pretty difficult, but not impossible. The tricky part I think would be making an airtight seal around it that would still let you service the filter as needed. About the only place I think you could sneak a filter in there would be between the blower motor and the evaporator core; the system "necks" down right there and might give you just enough room to swap a filter out without having to pull the dash, though access would still be pretty tight. The more I think about it, there's just not enough room for access...likely way more trouble than it's worth, IMO.

You wanna just keep debris out of the airstream, pull your wiper arms and cowl plastic, and cut a piece of window screen to cover the large holes in the cab openings that the cowl plastic sits on top of.

Richard

 

[Schurkey]

When the A/C system is working, the wet (from condensation) evaporator core does an OK job of removing dirt and pollen and such. Any particles that touch the core would be "trapped" in the layer of condensation, and drain out the duckbill.

That doesn't do any good when the A/C isn't operating, though.

I can't think of anywhere to hide a cabin filter that would allow for the element to be replaced without major labor.

 

[SuperTramp]

I found the drain and will look for water dripping out while AC is running. Unless you guys think otherwise, thought I’d run small, bristle bottle brush in from fire wall entry to remove any debris. The idea of using a screen under the windshield wiper grid came to mind and I’m glad to hear you had the same thought. I think the consensus is probably right about there not being a good place for the air cabin filter to be mounted, even if I was a fabricate one. The comment about the condensation serving as a washing agent in the coil was quite keen. Thanks for the insights.


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