Air Vent only works on High, no Low or Med (1 Viewer)

[revoltdeceased]

So i have searched around and without any luck. Maybe I am not phrasing something correct?

Problem:
Cab Air vents will only kick the fan on when on High. On Low or Middle settings nothing happens, fan doesn't turn on and no air gets pushed.

Troubleshooting:
I have checked my fuses under the hood and at drivers kick panel. It would seem that the fan motor is fine, just some contact or resistive module is not functioning. My co-worker, who worked on nissan/datsuns) said that many Japanese fan systems use wire wound resistors to get the lower settings but none on high (kind of like our fuel sending units).


Any thoughts or help would be greatly appreciated this summer, since i don't have any AC and its triple digits where i live. Thanks.



`91 22re 2wd

 

[87Yota]

Blower motor resistor. Look on the firewall on the passenger side close to the blower motor. Usually has two screws holding it in place and a wire connector. Replaced quite a few on my '87 in the past 20 years.

 

[revoltdeceased]

Thank you! I am meeting someone who rolled his `89, gettign his cloth blue bench seat for my 2wd commuter. When i see him i'll ask for that part. Thanks again. Now to find out how to pull that part. haha.

 

[jynx]

My money is on the switch. They are pretty cheap and I had a Toyota tech tell me they replace them regularly. Mine did the same thing a few years back.

 

[KLF]

Resistor. One screw. Behind the glove box. Very common failure, very easy fix.

 

[revoltdeceased]

I pulled out the glove box in the 5 min i had before work, i sa a little box and a relay next to it (90987-04002/056700-6780). Pulled the relay and the air wouldnt work on high, but thats all i had time for this morning. I'll look for the resister mentioned. If that doesnt fix it i'll look something else.

jynx - when you say switch, do you mean the mechanical one in the dash? hmm, i guess i coudl try and bridge contacts to test that. Any suggestions on isolating that as the fault?

 

[snobdds]

I also say it's the switch. Mine did the exact same thing...

 

[revoltdeceased]

well i have an 88 4runner and my parents have a 92 2wd pickup, i'll try swapping parts.

Now that i know the dang this is called a "blower" i was able to find 4crawlers site on it. I just took a look adn couldnt find my resister, I even traced all the wires around. "There is a fuse, a switch, a relay, a resisto pack and the blower motor attached to the fan." I can find the relay, and fuses... but not my resistor pack. hmm. lunchtime shade-tree mechanic time for me. Testing the switch will be an after work thing.

the funny thing is that this has been a problem for 2+ years, i just finally got an itch to fix up the 2-3 issues of this truck.


http://www.4crawler.com/4x4/CheapTricks/Blower.shtml

 

[revoltdeceased]

Found the resistor and it has 2 of 3 coils broken. Thank you all for the help. I am going to post some pictures when i get home to help out others. The location was a little cryptic and pics always help.

 

[jynx]

Good deal. And yes, I was talking about the mechanical switch. It uses a spring and detents with a little ball to catch each speed, kinda like the t-case detents only much smaller. Anyway, in my case I guess the ball had gotten soo hot that the plastic housing had gotten soft and the ball pushed into the plastic and I guess I turned off the truck with the switch in that position so it hardened back up and was stuck, so it would only close the circuit on hi.

I will have to keep this resistor in mind for future reference, just in case.

 

[flash02]

I know the OP found the problem but I figured I'd throw this out there for some good to know info.

The blower speed is controlled by varying the resistance of the ground to the blower motor. On trucks as old as ours the switch and or the resistor could be the cause, that being said the resistor takes very little time to remove and replace vs the blower switch.

 

[jgranthevagrant]

I just replaced both my fan switch and relay on my 1990 pickup. Both were bad.

 

[87Yota]

Found the resistor and it has 2 of 3 coils broken. Thank you all for the help. I am going to post some pictures when i get home to help out others. The location was a little cryptic and pics always help.

That's the problem. If the coils are broken it won't run on some speeds.

 

[revoltdeceased]

Blower resister replacement

These first 3 pics show how the old resister was broken on two coils. and the last of the three show a comparison to a new one. This is the resister for a 91 pickup that has the 4 lvls of air. The last picture shows the resistance of the coils, just in case someone wanted to make their own.

 

[revoltdeceased]

Blower resister replacement - Location

For those of you/us that have never done this before and wanted some pics of location and what the heck you are looking at/for.. this is for you.

The resister needs to be cooled in the ducting, and it downstream of the blower motor, about 2-4 inches down. if you are big like me its annoying to do without pulling out the 4 screws for the glovebox. Possible to do without pulling, but oh dear god so much easier.

The hanging cable in the first pic is the 4 wire plug that goes into the resister. Second pic shows the location without the resister, and Third pic shows it installed but not plugged in.

I hope this helps someone down the line, cuz thats what we are all here for.... help.

 

[revoltdeceased]

I also just wanted to note a couple things about those pictures. The breaks were in the wire, NOT THE WHITE COMPOUND. That is a thermal spreading ceramic compound that holds the wires in place. after heating and cooling hundreds/thousands of times and the constant vibration of the truck, the wires would break far too easily. Thus some "glue". I got some parts from a kid who had just rolled his truck, and his was broken from the accident. Too much good vibrations i guess.

Here are the resistances between contacts. ( in ohms, i dont believe it was anything like mega or kila.. just plain jane ohms)

M1-L= 1.1
M1-M2=1.0
M2-H= 0.7
H-L= 2.6

 

[MrClean]

Just wanted to comment how much I enjoy this forum and the knowledge that is here. My heater blower has never worked on Low since I got my '79. I found this thread in a matter of minutes and pulled my heater blower resistor out. Sure enough, one of the coils is broken (see pic). Found the replacement part on toyotapartsdeal.com for less than $10 bucks. Another issue resolved on this old girl.