Mine smells nasty. Does anybody know how to clean out the heater box without have to remove the whole dashboard? The Clymer manual is no help at all.

The plastic housing looks like a clamshell that might be able to be split with the rest of the components installed. I copied a picture from the Ford microfiche. Any way to split that big box on the bottom from underneath the dash?

Also, that pic is confusing because the blower motor faces the other way and is under the hood, not in the passenger cabin. thanks!

 

Did you get a mouse nest in it? If so I would take the blower motor off and clean it out with shop air. If not manually open the recirc door behind glove box and spray febreze in.

 

They also make a spray foam HVAC auto AC duct/vent cleaner that works well in cleaning. But yea, whatever is in there, be it a mouse nest or acculmulated debris, should be cleaned out first. Use the foam cleaner afterwards. Febreeze just masks the smell for a short time.

 

Poked around for quite a while on Saturday and it looks like there is no way to open that box. There was some tree trash in the box with the blower motor, but not really much crap. The squirrel cage fan wasn't too dirty. I ended up spraying a whole can of Lysol through the system and that just perfumed it.

I didn't see a way to get down into the air box in the cabin from the blower motor opening. Using compressed air like RGM suggests above sounds like a good idea.

I'm also thinking of connecting some thick fuel hose or something to my shop vac and trying to snake it in through the bottom or maybe through the blower motor opening. New project for next weekend.

 

Pulled the AC blower back out and blew out whatever I could with compressed air while vacuuming, It it doesn't look like you can actually get any crap beyond the AC evaporator (the "radiator" like unit that cools the air, #4 in the pic below).

It looks like the air comes in from the blue arrow on the firewall (upper left corner by #2). The air comes from the grill vents above the hood or from below from the cabin if recirculate ("Max") is selected for the AC unit. The air is sucked in by the blower fan and exits the fan housing through the AC evaporator #4 and out (now green arrow), into the evaporator housing to be redirected back through the firewall and into the cab where the heater core sits in the cabin air box (shown in post #1 above).

Said more plainly, it appears that if you have tree trash or a mouse nest in the HVAC system, it's probably in the blower airbox to the left of the AC evaporator (#4 in the pic below). I guess mice could get into that cabin airbox, but I didn't find anything and never saw evidence of mouse infestation (e.g, acorns) in the cabin.

Using compressed air, I blew out the fan box and the AC evaporator, at least on the fan side and most of what I got out was dry tree trash - nothing wet and moldy. I don't see any way anything could get beyond the AC evap coils (#4 below). I had already cleaned the evap coil with the foam cleaner last week and spray copious amounts of Lysol through the system (both through the intake behind the hood and the intake from the cabin behind the glove box). I also blew into all the vents inside the cabin and nothing came out of the air box inside the cabin.

Dunno if there's much else I can do at this point. It does smell better, but hard to tell until the Lysol wears off. We've had a couple days of rain here and everything was dry inside the fan blower housing. Time will tell.

 

Repeating a post from RonD commenting on a 2002 Ranger that appears to work the same way as the system I described above. Where is the cold air HVAC intake path?
ANY AIR FROM THE BLOWER MOTOR MUST PASS THROUGH THE AC EVAPORATOR FIRST and then through the firewall. So if you've got a bad smell from moldy trash, it's on the blower side of the AC evaporator (or in the coils).

Ron, you're just a fountain of knowledge about these old trucks.