Interior blower fan dead...blowing fuses.

[phyrefighterjay]

O7 Yaris 4 door well fellas here it is....A long time ago I had receipts that got stuck in my blower motor and ruined the first three speeds leaving me only with speed number four. For five years fan speed number four was very good to me. Then the blower motor finally Quit. I purchased another blower motor off of eBay for $65 and that worked on the fan speed number four for about a month. Once again with the replacement blower motor the previous three speeds did not work. The replacement blower motor would work every once in a while after hitting it softly with a rubber mallet. But not for very long...now all is kaput. I started with the fuses and realized that my 40 amp fuse under the hood was blown the interior 7.5 amp fuse was fine. I replaced the 40 amp only to have it blow immediately. I then moved to the rheostat/resistor and found that it was blown. Replaced the rheostat/resistor. Now I am befuddled to what is going on. I have a multimeter. Now what do I do? Obviously something is wrong with a ground here? Please help.

[CoryM]

You probably melted the wiring somewhere so it is now shorting to ground. They usually melt between the blower and resistor. Or maybe you crushed the resistor wires and they are shorted to ground. Try unplugging the motor and see if it is still drawing. This will confirm the wires prior to the motor are OK. After that, unplug the resistor, and plug the motor in and check the draw again. If still no draw, the problem is in the resistor.

I've had to replace every connector and part of heater fan circuits before due to melting. Never on a Yaris though.

Cheers.

[phyrefighterjay]

I don't see any melting or wire to wire contact. The guy at Napa said it is probably a bad blower motor. And that my problem lies there. What do you think?

[CoryM]

Definitely possible. They can fail internally, causing large amperage draws.

[CTScott]

Also check the 10A GAUGE fuse in the under dash fuse panel, as it feeds the coil of the HTR relay, which switches the power feed to the blower. The HTR Relay could also be bad, but he is fully integrated inside of the body ECU (which is within the under dash fuse panel).

[phyrefighterjay]

Well here's what I found out tonight. I plugged new 40amp fuse under the hood. Hooked up my multi meter and tested the female end of the plug ( The plug that hooks into the blower motor ) as soon as I started the test...the voltage kicked up showing juice to that plug....the wires got hot and the 40 amp fuse blew. so it is not the blower fan. I will check the 10 amp fuse to the relay but I'm getting continuity . What now? It could be...
1.a melted plug.
2 bad relay? (I hope)
Thank you so much for your help on this.

[phyrefighterjay]

Btw the ac is trickling cold air so I don't Think the relay is the problem

[CTScott]

The 40 A fuse feeds pin 1 of connector 4L. From there it makes no connection unless the HTR relay is actuated.

If the fan switch is off, the relay is not actuated. As soon as you move the switch from off to any setting the relay closes.

When the relay closes, it connects the black wire of the fan motor to the 40 A power feed. The blue wire of the fan is the negative side. It goes to the blower resistor (for speeds 1-3) and to the HI terminal of the blower switch (for speed 4).

http://i372.photobucket.com/albums/oo163/ctscott329/Misc%20Yaris/FuseBox-sm.jpg

[phyrefighterjay]

when I tested it tonight I would turn the blower fan switch to 1... The wires near the blower motor (which was not hooked up) got warm and then the fuse blew...what do you think is going on?

[CTScott]

I think that either the fan or resistor is drawing too much current. Try unplugging the fan motor and measuring the voltage between the blue and black wires on the connector, while switching fan modes. Also, with the connector off, measure the resistance between the two terminals of the fan motor.

[Bluevitz-rs]

when I tested it tonight I would turn the blower fan switch to 1... The wires near the blower motor (which was not hooked up) got warm and then the fuse blew...what do you think is going on?

As Scott said, measure the resistance between the ground wire and all other three wires.

[phyrefighterjay]

That is what I did. I was trying to rule out the fan blower as the problem so all tests were done with the connector off of the blower fan tested it got warm resistor blue

[phyrefighterjay]

Let me start over. Last night I disconnected the fan and tested the connector that connects to the fan. So the fan is not the problem. In fact when I checked the continuity on the fan it was fine. This is the test results from last night.this test was to ensure that I had voltage to the connector plug that connects to the blower fan.
1. Un hooked the connnector to the blower fan.
2. I put a new fuse into the 40 amp slot to complete the circuit.
3. Turned the key on to the run position
4. With the fan in the 0 position tested the blower fan connector...0 voltage.
5. Moved fan switch to position 1...voltage was shown, wires got warm, fuse blew.
I'm getting so frustrated. Here are my possibilities...
1. The connector melted and the jump is being made there and I can't see it.
2. It's in the switch/fan selector knob.
3. It's somewhere deeper, like the relay, fuse panel etc

[CTScott]

Try the same with the resistor unplugged. With the measurements you took the relay is fine.

[CoryM]

I'd unplug both switch and resistor. Plug in yet another fuse (it can be done using resistance too if fuses are getting expensive) Then ground the red wire at switch and leave it there for all the following:

Now jump the blue wire to ground at switch, then if OK blue at resistor. Fan should turn on full speed both times and not blow the fuse. This will rule out everything up to the switch and resistor. If ok, take jumper wire off, plug in resistor. if the fuse blows- replace resistor (it could still be wires, but very unlikely). If OK - take jumper wire and ground the black wire at switch. Fan should be on M1. If OK - jump green wire at switch to ground. Fan should be on M2. If OK - replace switch.

At this point, I'd bet the switch with it's multiple moving parts and contacts has failed.

CTScott: Any idea why so few cars use PWM for fan speed? Seems like it would be simpler/cheaper/cooler.

Cheers.

[phyrefighterjay]

I'm going to order a new fan switch. Only 30 bucks. Sorry, last post with jump wires was too technical. I might just run a switch and inline fuse direct from the battery at this point. Only need high speed on the fan. Is this possible?

[CTScott]

I'm going to order a new fan switch. Only 30 bucks. Sorry, last post with jump wires was too technical. I might just run a switch and inline fuse direct from the battery at this point. Only need high speed on the fan. Is this possible?

I don't believe it is the switch, as a bad switch should not make the wires at the fan heat up.

[CoryM]

I might just run a switch and inline fuse direct from the battery at this point. Only need high speed on the fan. Is this possible?

It is possible, but you would want to run it from IGN instead so you never leave fan on overnight. If the wiring to the fan motor is good, it could be done fairly easily. It's always best to fix the problem when possible though, rather than bypass it.

[phyrefighterjay]

What type of inline fuse do I use with this bypass procedure? How heavy of wire?

[phyrefighterjay]

I'm going direct from the battery.

[CTScott]

I'm going direct from the battery.

The fuse should be a 40A one, like what fed the circuit originally. You still have to be very careful, as 40A of current is enough to make a damaged wire, where not all of the conductors within the wire are intact, hot enough to start a fire, before the fuse pops.

[dj92]

CTScott: Any idea why so few cars use PWM for fan speed? Seems like it would be simpler/cheaper/cooler.

Because it requires pseudo-expensive semiconductors :laugh:
In fact, they use it for the automatic A/C (highly recommended to retrofit)
Sadly, I did not find an affordable fan, so I had to build a controller for the stock one on my own, but it was totally worth the effort.

[CoryM]

If you're going straight from the battery I wouldn't mess around with wire size. Not going to cost much more to use some 8ga, and heavy-duty fuse holders are typically that size anyhow. Make sure your fuse holder is rated for 40A+ as many are only rated to 30A. Same goes for the switch, use one that is heavy duty and rated for the current. If you ever fix it correctly, let us know what happened.

Regarding PWM, it just seems weird that a little controller costs more than all that extra wiring and resistors. But I guess resistors and copper are cheap. So what if they have a habit of melting? :þ

[dj92]

The wiring you can omit is far cheaper than the semiconductors I think :D