One of you mentioned this fix for opening the plenum, so my neighbor used his leaf blower in the vents in my Ranger. The AC would blow hot upon startup after the track sat and then would gradually blow cool air. The leaf blower seems to have helped.
The neighbor, at my direction to avoid damage, used the blower in each of the 4 vents for about 5 seconds. He also did not hold the blower outlet hard against the vent opening. I didn't want to risk damage.
Yeah, that was me, but I forgot the disclaimer, actually “disclaimers”.
This is not a recommended practice from TRS, and I don’t even know if I recommend it to anybody else, I just wrote up what I tried. My truck is a 300,000 mile toy. If it gets broken, it would just be something else to add to the list, but I wouldn’t want to break a new truck or a really good truck. In my mind, if it works, that’s great. If it doesn’t work, well, I would’ve had to go into the dashboard anyway.
Any leaf blower is going to generate much more pressure than the blower wheel in your heat and air will ever generate, and you’re pushing it in the wrong direction for the way everything is designed for the truck. I want to clarify that when I did it, it was not a matter of “just five seconds.” if the pressure is too great, something might break. I started at a distance and slowly moved in, and I was feeling for the back pressure coming out between the blower nose and the vent. I was trying to be sensitive to the flappers and whatever are inside the dashboard and not blowing one of them out into the driveway.
I have also had the problem of starting up the AC after the truck has run for a while, but has then been parked for a while, and it starts hot and very humid. That is not an issue with clogged vents and won’t be cured by the leaf blower procedure. That’s probably two things.
First, when the warm air from the interior blows over the cold evaporation coil, water will condense out and fall to the bottom of the housing that holds the evaporation coil. There’s a little drain that lets that dribble out onto the ground under the truck. Over the years that drain can get plugged with a little bits of bugs and leaves and dust and who knows what. If that drain is plugged, when you run the AC, the bottom of the containment will fill up with a little bit of water. When you turn on the AC, the first thing it’s going to do is to try to push that back into the car, the water that’s sitting around the bottom of the coil.
The other issue is that that housing is supposed to be insulated on the outside, especially the side that’s facing the engine and exhaust manifolds and such. That insulation gets beat up over the years and gets beat up as you work on your truck, etc. If that insulation is not perfect, when the truck is sitting after use, the very high heat of the engine compartment can penetrate into that housing and warm up the coil, hence the heat when it first starts up
It’s easy to say “replace the insulation,” but it’s kind of hard to get to it and get it installed perfectly. What I realized over the years is, it doesn’t have to be installed perfectly. Get some auto insulation, ideally material that has a foil face on the outside (reflects heat the same as light), and play around with it and cut it so you can get it down around most of the box. It doesn’t have to be all one piece. Then use some dabs of something like E 6000 to hold the pieces of insulation in place. You don’t need a lot of glue You may even want to overlap it if you can’t get tight seems between your pieces. It doesn’t have to look pretty, you just want to prevent the heat from the engine compartment from go ing directly into the evaporator coil housing.
I think I’ve got my drain cleaned, but I still have to pick up some insulation to better cover my box.
I’ll post when I get it done and how it works. But I’ve done it before, it may not make it perfect, but it usually makes a good improvement.
My questionable two cents, as always…
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