heater blower circuit?

[rrgrr]

Something (probably me) killed power to my heater blower -the fan fuse was blown, and when I replaced it, nothing. I've hotwired a battery on the pass side floor to run it.

 If someone could describe the circuit path of this thing it might save me some digging. The 2 wires on the blower are green/white(grnd) and blue(+). Do they come from the fan speed knob? 

[Gloyale]

Pretty sure the ground is actually the blue wire, and comes from the heater switch.

 

The green/white wire is POS 12v from the relay.

 

Likely your're relay is blown.  What year and model?

[ruparts]

hi ,

  you might have a burned out blower resistor, it is mounted in the blower case , pretty sure it has a 2 wire connector, once removed it has several little coiled wires that look like springs in a row,  look for a plastic thing  with wires to it mounted with 2-3 screws into the blower case. 

   the blower relay is driver side under the dash, above the ecm , there are 4 relays there,,  it's the one with, green/white, red/white, red/yellow, and blue/red.  the others are 2 for lights and 1 for rear defrost.

  you didn't say,  but this information is for a ea-82 series like 1988 , so if you are dealing with a ea-81 it's not exactly the same.

Edited December 9, 2013 by ruparts

[rrgrr]

It's the 85 EA82. I might have the wires switched I cobbled a harness for the blower and clipped to it, it's a (hot) mess.

[Gloyale]

hi ,

  you might have a burned out blower resistor, it is mounted in the blower case , pretty sure it has a 2 wire connector, once removed it has several little coiled wires that look like springs in a row,  look for a plastic thing  with wires to it mounted with 2-3 screws into the blower case. 

   the blower relay is driver side under the dash, above the ecm , there are 4 relays there,,  it's the one with, green/white, red/white, red/yellow, and blue/red.  the others are 2 for lights and 1 for rear defrost.

  you didn't say,  but this information is for a ea-82 series like 1988 , so if you are dealing with a ea-81 it's not exactly the same.

 

Burned resistor the fan would still work on high.

 

He's got a bad relay.  It's one of the 4 above the left side of the column on back of dash.  Look for the one with the big Green/white wire that will be it.  IIRC it has a Black connector.  Just look for hte one with the G/W wire

[Cougar]

Just an added note in case you aren't aware of it. The speed control resistors are located on the return side of the circuit for the blower motor. Power comes from the relay, then to the motor, and then on to the switched resistors and ground.

[rrgrr]

Thanks guys, exactly what I needed. I jumped the relay location grn/white to blue and got 3&4 fan speeds; ordered the new relay from napa.

[rrgrr]

The new relay made no difference. The jumped wires on the relay socket are green/white and blue/red. They are the copper slots, the other 2 ground. Makes no difference whether the key is on or not, it's hot. It runs at speeds 3&4, and turns off.  I can live with this jumper but I don't know why it works. Still trying to understand why this thing is getting power with the key off.

[Gloyale]

The new relay made no difference. The jumped wires on the relay socket are green/white and blue/red. They are the copper slots, the other 2 ground. Makes no difference whether the key is on or not, it's hot. It runs at speeds 3&4, and turns off.  I can live with this jumper but I don't know why it works. Still trying to understand why this thing is getting power with the key off.

 

Your not understanding relays.

 

The Blue/red is 12v from fuse box, to the relay. 

The Green/white is 12v out to the fan when the relay closes.

 

The Red/yellow wire should be 12v signal when key is turned on. From fuse 12 15amp.   If key is off, this wire has no power, and the relay is open so no power goes out the Green/white.

 

The last wire should be Red/white.  This wire should have ground.  Non A/C ground all the time........A/C models ground only when one of the mode select switches is depressed (heat/vent/defrost/etc..)

 

Sounds like you either have no power to Red/yellow or no ground on the Red/white.

 

This means the relay never closes.  fix that and the relay will work.

 

Then replace your blower resistor because your 1 and 2 speeds are burned out.

Sounds to me like the power is not getting to the trigger wire with Key on. 

[robm]

I seem to recall this relay turns on with the ignition, but I don't know if the ignition puts 12 V to the coil, (probably) or provides the coil with ground,   Check that it is getting 12 V to the hot side of the coil.  Check that there is ground on the other side.

 

Working on these relays is a total PITA.  One good thing is all the relays that look the same, are the same, and you can swap them around to test if you have a bad one.

Edited December 20, 2013 by robm

[rrgrr]

Thanks, guys. Clearly I do not understand these relays, I'll run some tests and see what I come up with. I seem to have some other gremlins, as well...

[Cougar]

It's pretty simple these days to find information on things you have a question on. For some reason I can't copy the web site to this post. Do a search on how a Bosch relay works. You will find all kinds of info on this and become a relay expert.

[rrgrr]

Your not understanding relays.

 

The Blue/red is 12v from fuse box, to the relay. 

The Green/white is 12v out to the fan when the relay closes.

 

The Red/yellow wire should be 12v signal when key is turned on. From fuse 12 15amp.   If key is off, this wire has no power, and the relay is open so no power goes out the Green/white.

 

The last wire should be Red/white.  This wire should have ground.  Non A/C ground all the time........A/C models ground only when one of the mode select switches is depressed (heat/vent/defrost/etc..)

 

Sounds like you either have no power to Red/yellow or no ground on the Red/white.

 

This means the relay never closes.  fix that and the relay will work.

 

Then replace your blower resistor because your 1 and 2 speeds are burned out.

Sounds to me like the power is not getting to the trigger wire with Key on. 

Thank you for helping me try to understand this. I think I have determined that red/white is not grounded. I followed it, but It goes into that harness and I don't want to get into that much if I don't have to -Can I just cut it and ground it elsewhere?

[Gloyale]

Thank you for helping me try to understand this. I think I have determined that red/white is not grounded. I followed it, but It goes into that harness and I don't want to get into that much if I don't have to -Can I just cut it and ground it elsewhere?

 

That would probably work.

[coronan]

I have a similar situation on an 82 brat.  

 

My manual says 80 - 84 has the same wiring.

 

I found the blower relay above the fuse box.  when the key is on it closes 12v from white to green.

 

At the switch all legs have power except black (ground).  Resistance on each leg was 50 to 250 ohms.

 

I am to understand that the relay sends power to the blower but is switched on the ground side????

 

So if my blower does not come on but the switch has power and ground = bad blower motor

Right????

[ivans imports]

Change the blower resistor is next to fan held in with 2 screws and has 4 wire plugin

[coronan]

I'm spelunking under the dash for the blower resistor.

 

to the left of the glove box is this:

6 wires

 

Behind the glove box is this:

2 wires

 

Is the blower resistor hidden in this rats nest?

 

??????

Thanks!

Edited September 24, 2014 by coronan

[Gloyale]

I have a similar situation on an 82 brat.  

 

My manual says 80 - 84 has the same wiring.

 

I found the blower relay above the fuse box.  when the key is on it closes 12v from white to green.

 

At the switch all legs have power except black (ground).  Resistance on each leg was 50 to 250 ohms.

 

I am to understand that the relay sends power to the blower but is switched on the ground side????

 

So if my blower does not come on but the switch has power and ground = bad blower motor

Right????

 

Unless your brat has A/C installed.......you don't have a Fan relay.

 

Read my writeup in the USRM about the EA81 blower power supply.

 

http://www.ultimatesubaru.org/forum/topic/140176-ea81-blower-circuit-jumperrelay-connection/?do=findComment&comment=1179606

[coronan]

I have AC.

 

I'm looking for the Blower Resistor Box.

Edited September 24, 2014 by coronan

[coronan]

Still haven't found the blower resistor box.   Is that where all the blue wires lead to from the switch?

 

I pull the blower an jumpered power to it.  It spins fine under its own power.

 

Funny thing is it has power when the switch is in the off position but none of the on positions.  

 

I'll pull the blower switch out again tomorrow and follow the blue wires.

Hopefully they lead to buried treasure.

 

I shopped for a resistor and a new switch but could not find anything at Orilies, Napa, Rock,

 

Autozone (though i try to avoid shopping there)  Suggests this part:

http://www.autozone.com/autozone/accessories/Electrical/Relay-and-Resistors/_/N-2659?filterByKeyWord=blower+resistor&fromString=search

 

But its only 3 wires???

http://www.autozone.com/autozone/accessories/Santech-Red-dot-units-71R-1450-blower-resistor-block/_/N-2659?itemIdentifier=262814_0_0_

 

I should just put in a PWM.....

http://www.amazon.com/Pulse-Modulation-Control-Switch-9V-60V/dp/B00MN6R6JW/ref=sr_1_8?ie=UTF8&qid=1411594954&sr=8-8&keywords=pwm+20a

[Gloyale]

resistor pack is mounted IN the ducting.....I believe you can see it on the drivers side beside and above the gas pedal. 

 

4 pin connector

 

The blues wires through the switch and resistor are the ground for the circuit........that's why you see power on the wires when it's off.......12v coming through the fan from the relay.  When you turn it on, it closes the circuit, and drives the volts on the blue wires to 0 v.

 

The switch connects the blue wires to ground.

 

What you need to do is test for power on the Green/white wire at the blower w/ key on.  If yes....then relay is good.

 

Then test the black wire at the switch to see if it's connected to ground.

 

Even if the resistor pack is bad the blower should work on high (4).  So if it doesn't work at all the problem is either power to the motor, or ground to the switch, or some break in the wiring between.

[ivans imports]

3 inch from blower motor

[ivans imports]

whoops on newer on old one is just above heater coolant valve

[coronan]

Still plugging away at this.

 

Here is continuity through the switch.  Seems Normal:

All Circuits are open in the off position.  

Yellow to Black is Closed in Switch position 1, 2, 3, 4.

Switch Position

1 = Black - Yellow only

2 = Black - Blue w/ Yellow Stripe

3 = Black - Blue w/ White Stripe

4 = Black - Red w/ white Stripe

 

Black wire is grounded with no resistance.

 

With my multimeter Neg lead clipped to ground (sheet metal):

Now, if I check for voltage, at the fan.  The fan has voltage in the off position, as it should from the relay.  The speed control switch should be switching ground per my diagram.

When the Switch is in the 1, 2, 3, or 4 position Voltage is interrupted.

 

Unplugging the fan shows that power is coming from the RED /w White Stripe.  Not the Green w/ white stripe.

 

Do I have some funky, home made bull or what?

 

The fan looses power when the switch gets unplugged at either plug.  Which suggests the fan is getting power from the yellow w/ White stripe at the resistor pack.

 

Trying to jumper the green wire to ground does not engage the fan.   Nore does jumping the red to ground or red to black.

 

What the diagram does not show is what controls the relay to come on and off.

 

Please tell me I have been looking at this too long and missed some thing simple.

 

 

 

 

Edited September 30, 2014 by coronan

[coronan]

Found my problem.

 

Thanks to Gloyale for pointing me in the right direction with this image. 

 

<a href="http://s209.photobucket.com/user/Gloyale/media/IMG_0192_zps09c006bc.jpg.html" target="_blank"><img

src="http://i209.photobucket.com/albums/bb29/Gloyale/IMG_0192_zps09c006bc.jpg" border="0" alt="A/C jumper EA81 photo IMG_0192_zps09c006bc.jpg"/></a>

 

This particular relay lives mounted directly above the fuse box on the drivers side.

To get to it pull the fuse box with 2 screws.  Then pull the bracket with 1 screw and bend it down.  Vola!

 

Even though the Fan had power from the AC circuit it would not run.  ( I still don't know why. )

 

The glass fuse in my fusable link was rated 20 amps same as the blade fuse in the box.  They are so close to one another I'm tempted to bypass it.  It looks like my white wires got hot due to a bad connection.  

 

I'm not sure of its purpose.  

Any one else had trouble with this fuseable link?

Edited October 1, 2014 by coronan