bhrbrewery

Hi all,
I have a 90 4Runner 3vze 5spd. I am new to this diy vehicle arena but I want to learn. I have been researching this problem for a few weeks now and I can't seem to get a definitive answer.
My heat is hot, my ac is cold but neither makes it through the vents with much force. One mechanic says that it is a common problem and that he can fix it for a few hundred. One says that his 4Runner has about the same force through the vents and he just thinks that is how Toyota made it...frickin' ridiculous!
Intuitively I would say there is a clog in the ventilation system. The blower motor runs quiet to loud when the selector runs right to left so everything seems to work alright.
Any advice? I am driving with my toddler across country to Minnesota and I just may need the heater to work by the time I get there. Any help would be greatly appreciated.
Thanks,
J

Saint_Berzerker

I have the same thing. My compressor blew up a month ago, and I replaced it w/ a new one...same problem, but the air is plenty cold.

I took apart the blower motor assembly and cleaned the thing like new...thinking that would help...but nope.

I saw in the cooling unit, which is next to the blower, that my evaporator thing looked pretty filthy. After doing some research in the FSM, I saw that indeed a clogged evaporator can cause "low velocity of cool air", as well as a clogged expansion valve.

I haven't gotten around to it yet, but those are my next project after my ball joints.

I have to crank it up to the highest speed just to get a modest amount of flow. It's ok, but I'd like it to blow a lot harder. It gets noisy all the way up.

Tdubbs05

i'd check out your fan and make sure it's actually working to it's potential. (cables pulling the right things?) take your passenger side dash apart and you'll see how everything works. my 94 4runner blows tons of air on full power.

ChickenLover

My '95 blows a lot of air as well. Are you sure all the hoses are connected to the vents (behind the dash)? I've noticed that mine blows a little harder when it is selected to recirculated air (as opposed to fresh). Saintberzerker is right, the fan has to blow the air through the evaporator (regardless of a/c being on or off). So a clogged evaporator will certainly have an adverse effect on the velocity of the air coming out of the vents.

yota_krazy

Just wondering, a lot of new cars have cabin filters that filter the air before it reaches the evaporator. Is there any way to mod one in? I would also suspect a clogged evaporator if the air volume wasnt up to par.

bhrbrewery

Rockin! The clogged evaporator is what the initial mechanic told me so that makes me feel good about that guy.
I will go hunting in the dash this weekend to see if anything looks messed up. Is it correct that in order to clean out the evaporator, the ac needs to be discharged?
Also, I am going off a crappy old manual so if anyone has recommendations for where to find better diagrams for whats going on behind the dash that would be awesome.
Thanks again for the info
J

yota_krazy

to a complete cleaning of the evaporator then yeah you do need to discharge the a/c and remove it from the evaporator housing. Im not sure on this model if you need to remove the dash to get that puppy out or not. If you can, then remove the entire evaporator housing and give it a good cleaning too, all kinds of crap can store up in there. Also make sure not rats have made a nest in there! I have seen that plenty of times but you probably would have smelled the buggers already. good luck!

^VooDoo^

There is also one other last place to check.
Its the vents between your winsheild and the hood, This is where the outside air comes in, You pop the hood and pull the luvers off then the little black screens and take a look around for buildup, Sometimes and I dont know how, Paper and leaves get in there.

Also if you do not have the insolation between the exhaust cross pipe and firewall you can have warping or melting of the venting feed tube That flows
the air in.

greasyglue

94 4runner 4x4 3.0
So I have limited air flow and not so hot heat in the cab, when I select cold air from outside it blows strong but when selected to outside air and heat the amount of air is significantly less and not as hot as it should be. I have back flushed the heater core twice for about 40 minutes each time there are NO clogs or leaks,system does not overheat. So I recently removed the blower motor and was wondering if I could shop vac thru (the way of air flow the blower motor moves)there to possible clean up the evaporator without removing it and avoid having to discharge the system.anyone do this with positive results?

maco35

I did this and now the air flow is amazing. https://www.yotatech.com/forums/f116...trucks-286766/

Terrys87

iTrader: (1)

^^^Glad to see it worked for you.

As far as trying to clean the evaporator without removing it, I don't see a way as there is not enough slack in the hoses to let the evaporator slide far enough back to remove the covers and get access the evaporator. Also my experience to clean the evaporator, really takes a good pressure washer to get down in the fins to get the dirt out.