Blower not working unless I reset fuse.

[Ktaco]

2005 v8. About 203k. I've had it 4 years with no issues regarding the blower. I am in New Brunswick, Canada so yes it's cold this time of year.

So just for about a week now I've had a reoccurring issue with the blower. Went out one random morning and found that the blower was not working on any speed. The lights show up on the control panel, I can switch vent positions and hear the actuator move the vent. Anyway after a bit of fiddling around I found that if I remove a little 7.5amp fuse labeled "heater no.2" from under the hood compartment and replace it the blower fires right up. It then works on every speed like it should, no obvious noise or anything that would give me signs of a faulty blower motor. If I do this in the morning I am usually good for the day. I can go running around to stores, stop and go, etc and the blower will work when I start the vehicle. Let it sit overnight again and same thing, no blower until I reset that fuse.

So to be clear the fuse it not blowing. I simply just take it out and put it back in and the blower will work instantly as it should. I have replaced the fuse just to make me feel better and eliminate that as a issue. I've read of ice build up being a issue but in my case that doesn't make sense as it starts working when I reset the fuse. I also don't think it's the resistor as a sign of that being faulty is usually only blowing on high speed and no others. I have seen a post about someone pulling that same fuse to "repair" theirs but no follow up on if it was a reoccurring issue or what the final fix was.

Tonight I plan on pulling the blower and putting it down by the woodstove over night to inspect it and remove any possible moisture. I'll disconnect the battery and leave it unhooked all night to give everything a good reset. I have a few parts coming in the mail from a junk yard and got them to throw in a few relays. I did have a blinking AC light twice this summer so I figure I'll change the AC relay and the heater relay to see if that makes any difference. Other then those things I cannot really think of what could be causing this issue and don't want to just jump into buying a new blower motor for nothing.

Sorry for the long post but I wanted to give as much detail as possible. Does anyone have any other ideas on what to look for or better yet someone that has had this issue and knows the fix? Thanks.

 

[zameul40]

Sounds like a stuck relay.

 

[jbtvt]

Check the terminals for corrosion. Seems more likely that your fix would have to do with jostling the connections than interrupting power, do you get the same effect smacking the fuse box? I've also seen intermittent issues like this on a Mercedes van due to the spade connectors not being a tight enough crimp but never on Toyota. If it is a relay issue they can be pulled apart and fixed in a few minutes, just run a strip of fine grit sandpaper over the contacts

 

[Ktaco]

Check the terminals for corrosion. Seems more likely that your fix would have to do with jostling the connections than interrupting power, do you get the same effect smacking the fuse box? I've also seen intermittent issues like this on a Mercedes van due to the spade connectors not being a tight enough crimp but never on Toyota. If it is a relay issue they can be pulled apart and fixed in a few minutes, just run a strip of fine grit sandpaper over the contacts

I can hit the blower motor, physically turn the blower by hand, and tap relays but nothing seems to get it going other then pulling that fuse. I'll check connection in the fuse box today. I also took the blower in the house last night so I'll install that again.

As for the relays I watched a helpful video last night. There's a 60amp fuse that sends power to a big heater relay. If that relay works it sends power to the little 7.5amp fuse I keep having to pull. I'll pull apart that relay and clean it if need be.

 

[delstele]

I just replaced mine last week she just hit 190,000 . It started with low output on any setting if I shut the 4runner off it would be fine for a day or 2 then start acting up when it was on for a few hours. Once I got the OEM unit out spinning the squirrel cage by hand it was obvious the bearing was dragging. This may be why yours is intermittently cutting out..

 

[jbtvt]

Even though it's probably not your issue, if you already have the blower out it's worth oiling the bushings on both ends to avoid this ^. Been a few years since I did mine but I recall having to support the housing on 4x4s and pound the rotor out to access one end. Non detergent oil is recommended, synthetic compressor oil or the like is best if you have any. I've got a few fans from the early 1900s that still work great. They all used to come with oilers for the bushings, even through the 60s it was common on industrial fans.

There is a second contact for that relay in the off position, so it may indeed be sticking, there would be no power to either side of 7.5amp fuse if it were. If there is power there then the problem is likely in the contacts at that fuse or in the blower motor controller. Here's your circuit

 

[Ktaco]

Little update. The blower has been working as it should for the past 3 days. It's not like the weather has warmed up either, still hovering around -25 Celsius in the mornings.

So in summary I removed the blower motor and put it by the woodstove overnight. No water came out of it. I blew it out good with compressed air before installing. Then I removed the heater relay and the a/c clutch relay. The a/c relay cannot be disassembled so I just gave it a few good taps on the bench and reinstalled. The heater relay does have a plastic cover that comes off. There was no visible corrosion or water inside. I gave it a few shots of contact cleaner and lightly blew it out with air then reinstalled. The battery was unhooked over night while doing all this.

Time will tell if it holds up but so far so good.