I picked up this truck last year in May. I noticed when the blower was on high there was little to no air flow coming out the vents. I figured since its coming up on winter i better get this solved.
I checked the blower cage to make sure it was turning, it is. Had to be a restriction in the dash so i pulled the blower motor housing out an the Evap core housing out and the Evap core was completely plugged by a mouse nest. I simply removed the Evap core, cleaned out the box an reinstalled everything.
I know have air flow out the vents..

 

A pic of the core itself.

 

Gee, that looks familiar

 

Your truck must of sat for way to long too.

 

That's pretty bad. I had mine apart when I was fixing the A/C in my 87 4Runner. After 335,000 miles it only had a few leaves and some dust in there.

Just some more information in case the evaporator isn't the problem, the blower motor can be faulty even if it spins at all different speed settings. The electric motor can wear out. My 4Runner didn't have as much air flow as my old Pickup did. With twice the mileage is twice the wear on the motor. The brushes can be replaced but make sure the commutator isn't worn as well. If so, Advance Auto sells a replacement for $45 or so. After replacement, the fan is audibly faster and you can feel the improvement out the vent.

 

My 4Runner had 330,000 miles at the time of the blower motor replacement. So unless your vehicle has similar mileage, it's not likely but it's worth checking.

 

My pick up has 205k on it.. i know it sat for a couple years due to the frame being rusted in half behind the cab. Frame has been redone an i've been driving it from time to time an fixing issues along the way as $$ allows. After removing all the crud from the evap core an the core itself. The air flow from the vents is great now. Had no problems heating the cab up last night while i was out driving around testing, even had to turn the heat down. Where as last year it would be on high the entire 20 minute drive to work an there was very little heat coming out anywhere,an the windshield would barely stay defogged/defrosted.

 

I got to play the heator core game too. Last winter, it decided to fail. And by fail I don't mean get clogged and stop working, I mean leaking just enough to create steam in the cab and leave a nice film on the inside of the windshield. Guess what the weather was that week while I waited for the new one to arrive, not a day above 20F. And being a college student means I don't have a garage while I'm away. But fortunately, my boss let me use the shop one night so I didn't have to install the heater core in a snow storm. Instead, I had a heated workshop.

The heater core is by far my least favorite repair but the results were great. My heat had always worked but only at about 60% of what I would have liked. Not great but not bad enough that I wanted to do the repair. After the new heater core install, heat worked 100%.

 

It takes alot of patients for dash work. I've done heater cores in alot of vehicle's.. i actually enjoy it. But yea when they rupture an steam up the window those are the worst!

 

It sat outside most of it's life by a house in the woods. You should've seen the nest of nuts in the airbox, and on top of the intake manifold.

 

Its amazing how many of these little trucks just sit because of small issues. Thats ok though..more of them to find for those of us that have the ability to revive them.

 

It didn't just sit. The PO ran it the whole time. He actually ran it on 5 cyl., until he blew the engine entirely.

 

Holy crap! People will drive anything lol

 

I know this is a few years old but this is happening in my 90 pickup 3.0 with 312k on it. what is the best way to get to all of that? i can't seem to get it all apart? any diagrams or pictures of taking it apart?

 

Even though this is for the 84-88 https://www.yotatech.com/forums/f116...trucks-286766/ it is basically the same for the next generation of trucks. I think all you need to do is remove the glove box to get to the evap on yours.

 

Very little to none comes out of the defrost but when I move the lever over to cold then air will come out not very much tho I mean it's half decent but feel should be more then what it blows out any tips on what I need to fix or replace

 

Any chance you know of a way to remove/clean the housing for that evaporator without removing the evaporator itself? Had a mouse decide to make it's home there then die and I need to clean it.

 

I have a 1988 Toyota with the exact problem. The heater vents work better than the defrost. But still think they should blow more air out. I am removing the evap core and cleaning it out. I bought my Toyota used so, that is probably the problem.Thank you.

 

I have similar question(s).
1) If blower is upstream of it, can it be accessed with flexible vacuum hose through the blower housing?
2) Is it possible to make a small opening, say a 3/4 inch to an inch in diameter on upstream side which can also be accessed by small crevice nozzle?