I've got a '02 1500 and after running the AC I noticed a new noise when running the fan. The next day I turn the fan on and it's making this weird noise, almost like the fan motor is going but that's not the cause as I'm getting full power and everything is working as expected. My father-in-law hears this and says the noise is the fan pushing the air and the sound comes from water being in the path of the air. He proceeds to tell me that it sounds like my plenum is clogged and there should be some tube under the truck that I can put a hanger or something up through to unclog it? Another sign that this is the issue is that the windows are fogging if I run the fan. Guess that is from the air passing through the water that is backed up.

Next day I run the truck for 15 minutes with the AC then shut it off (Did this to get some condensation to come from the tube he speaks of). Hmmm, nothing is dripping and considering temp and what not I know something shouldn't dripped.

Can anyone confirm or deny for me that this could actually happen? Not looking for a step by step but is there a hose under there? I've searched and all I find is crap on the plenum gasket issue from a few years back.

Thanks for any advice.

Ryan

 

Yup,
That can definitely happen. The water that condenses out of the air, like the condensation on the outside of the glass on a humid summer day, as it passes through the a/c coil runs off the the fins into the bottom of the air box (plenum). There is a drain tube that it drains from, and yours is most likely plugged. I can't tell exactly where its at, as I haven't looked or needed to deal with that on mine yet. It should be somewhere near the base of the firewall directly under the a/c coil, air box area. Be gently while trying to clear it, your a/c coil is at the other end of that tube. Actually, you might try doubling over some soft mechanics wire, twisting it to the point that there is a small loop on the end, and working that up into there.

Good Luck,
Hope this helps

 

Gone_Fishin' thanks a lot. I'll see what I can do and be sure to post a follow-up for others.

This actually made our last fishing trip rather annoying as we were running the AC on the way back. UGH.[:@]

 

Don't wait too long as the continuous moisture usually leads to mold in the plenum. Thats where the "musty" smell comes from

 

Interesting you mention that cause there is a bit of an odor the my 'other half' has mentioned. The truck had been sitting for a good year prior to me buying it...my guess is that some Oregon pine needles and other debris most likely found there way down inside the tube.

 

Considering pine needles would have to defy gravity to get in there, I'd wager it's clogged full with spider webs or egg sacks... Learned it the hard way myself. If I go on vacation without my vehicles the wrong time of year, I get my brother or my neighbor to run 'em for 20 minutes every other day, otherwise I come home to the problem you just described.... Damned spiders!
(They mess up my bbq grill too if I don't use it often enough!)

 

I guess my deal is I don't totally understand what's going on here with this plenum. I was under the impression that all the water and debris that got inside the grill on top by the wipers ends up going down this duct through the plenum? I'm gonna check it out this weekend we don't have a big spider population but you could be right. Now I just need to find the damn hose.

When I bought my Webber it was funny that a piece of their marketing material spoke to being 'spider proof'. I never realized they were such an issue.

 

Don't forget the cowl intake on top. They are all connected to the central air distribution box (plenum).

 

Are you saying don't forget to take it off and clean under it?