Mikevan10 Posted February 9, 2012 Share Posted February 9, 2012 The heater fan on my 1992 Legacy sedan is not working, as I found out driving home from work in the snow last night. My first move is going to be checking the fuses, however I have a wiring diagram for my 1997 Legacy here at work and I was just taking a look at it and, among lots and lots of other stuff in the air conditioning control circuit, I see there is a Blower Relay. If the fuses are all good, I am thinking that the next thing to go after may be that relay. Does anyone know where the blower relay is located on a 1992 Legacy sedan? Any other troubleshooting suggestions would also me much appreciated! Thanks, Mike V. Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted February 9, 2012 Share Posted February 9, 2012 I had a similar problem with my 91 Leggie. I thought the fan motor went bad, so bought one from a wrecking yard. However, upon installation, I found the fan unit full of tree leaves and crud to the point of preventing the fan from rotating. I cleaned out the crud, and the original fan unit works good as new. It is not difficult to remove the fan unit. You will need to remove the glove box to gain access, but that is not difficult. Just remove a few bolts, and it is removed. Quote Link to comment Share on other sites More sharing options...
Mikevan10 Posted February 14, 2012 Author Share Posted February 14, 2012 I have determined that the blower motor irself is just fine. The motor does not operate at any speed so I do not believe the ptroblem is with the resistor circuit that controls the fan speed. So it looks to me like it is either the fuse or the relay. Wrking with a Haynes manual, it is not clear which fuse box the blower motor fuse is in and examining the markings on the fuse box covers is not much help. Nor can I locate the blower relay. According to the Haynes manual, it is apparantly up under the dash to the left of the steering column. There are supposed to be several relays in this area but I only see one which, if I recall correctly, has a blue connector. This does not match with the info in the Haynes. Can anyone help me locate the blower relay and/or pinpoint the appropriate fuse(s)? Thanks, Mike V. Quote Link to comment Share on other sites More sharing options...
Cougar Posted February 15, 2012 Share Posted February 15, 2012 (edited) I think the relay is near the dash fuse panel but not real sure of that. One simple thing you can do to prove the resistor pack is the trouble is to check for voltage at the blower motor while it is supposed to be running. Turn the speed switch to maximum speed. Then see if there is voltage getting to both of the blower motor leads while things are connected normally. If you do have 12 volts at those points then the fuse and the relay is ok and the trouble is with the resistor pack most likely. You should be able to ground the lead of the motor that ties to the resistor pack and it will turn on the motor if that is correct. Just make sure you don't ground to power side of the motor leads. The grounding side for motor passes through the resistor pack so directly grounding the wire on the motor return side simply bypasses the resistor pack. Edited February 15, 2012 by Cougar Quote Link to comment Share on other sites More sharing options...
ivans imports Posted February 15, 2012 Share Posted February 15, 2012 the heater fan relay is located on drivers side of dash above the computer on top left side atached to a braket its the relay with a red and white wire and a green and white wires on it its a bugger to get at i have had to change 3 of them thiss year i take a long flat screw driver and come in from the left edge of dash and pop it off the braket and then you can pull the relay down on harness a bad relay has disscoulord contacts will look like copper instesd of brass Quote Link to comment Share on other sites More sharing options...
Cougar Posted February 15, 2012 Share Posted February 15, 2012 One thing you can try doing to see if the relay is the trouble is simply tap on it using a screwdriver handle. If it is bad it will usually make the motor turn on for at least a brief period. 1 Quote Link to comment Share on other sites More sharing options...
Mikevan10 Posted February 15, 2012 Author Share Posted February 15, 2012 Thank you Cougar and Ivan for jumping in on this. I really do appreciate it. I also really hate to have to do what I am about to do and that is to first ask for help, and then when help is volunteered to contradict it! But I am only trying to be logical/scientific. PLEASE bear with me. First off, I should have mentioned that the first thing I did, upon locating the blower itself, was to disconnect it and put a volt meter across the two pins in the connector. With the ignition on and the heater "ON", I believe the meter read about 6 volts across the pins, regardless of the fan speed switch position. I am not sure about this so I will test this again tonight to confirm. I do understand that the "grounding" side of the motor is connected to the resistor pack, but it also (in parallel, via the BY wire) is connected directly to the fan speed switch, which, if on the HIGH position, should connect it directly to "ground". Since the motor does not run even with the switch on HIGH and since the voltage across the pins does not change, I was thinking that this ruled out a problem with the resistor pack. But I guess it does not rule out a problem with the switch itself. I really should run the test Cougar suggested and connect the "ground" side (BY wire) of the motor to ground (with everything connected normally) and see what happens. I could also check the resitance from the pin connected to the BY wire and "ground" with the fan speed switch in various positions. I will look again and see if I see the relay mounted on a bracket ABOVE the computer (to be honest, I did not know that the computer was in that area on this vehicle). But, Ivan, my wiring diagram shows RY, RB, GB, and BR wires connected to the blower relay. It does not show any RW,WR, GW or WG wires connected to it. Again, I hate to contradict someone who is trying to help, but are you sure of these colors? Thanks again guys. I will try to take another look tonight. Thinking about this now, I am not sure how I concluded before that the problem was with either the fuse or the relay..... Mike V. Quote Link to comment Share on other sites More sharing options...
Cougar Posted February 15, 2012 Share Posted February 15, 2012 Another thing you can do with your meter is check the voltage on the B/Y wire going to the motor, with the meter reference to ground, while things are connected normally, and the speed switch is on HIGH. If that part of the circuit is ok then you should see close to zero volts at that point. If that checks out move the meter probe to the other motor lead which will be the power side of the circuit. You should see 12 volts there if the fuse and relay are ok. If the voltage is low then either the relay connection or the fuse connection is bad. Quote Link to comment Share on other sites More sharing options...
Mikevan10 Posted February 16, 2012 Author Share Posted February 16, 2012 I had a few minutes to do a bit more testing last night. The first issue I had was that I was unable to make good "back connections" in order to take measurements with the connector connected to the blower motor. So I only took measurements with the motor disconnected. Here is what I found: Resistance between the BY (i.e. ground side) pin to chassis ground=0 ohms, regardless of the fan speed switch position. Voltage between the BY and BR pins in the connector = 5 volts (approx.), regardless of the fan speed switch position. Of course this is with the ignition ON and the mode selector switch in the HEAT position. The voltage drops to zero if I turn the mode selector switch to OFF. I then resumed my search for the blower motor relay. I did manage to spot the heavy gauge BR and RY wires WAY up under the dash. They are so far back up in there with so many other wire bundles, connectors, etc. in the way that it was difficult to even get a finger on them. I could NOT see where they conected to any relay, but I guess it must be up in there somewhere. If I ever do find it, I cannot imagine how I will be able to disconnect/reconnect it without first moving several wire harness out of the way (something I really do not want to do). I did spot a brown connector and a green connector up there that I believe are connected to other relays so I think I am looking in the right area. The fact that I only see 5 volts at the blower motor connector makes me still suspect the relay, or I guess it could be a bad connection somewhere. But I am also surprised that the fan switch position has no effect. Any comments or suggestions? Thanks again, Mike Quote Link to comment Share on other sites More sharing options...
Cougar Posted February 17, 2012 Share Posted February 17, 2012 As you know Mike you should only have zero ohms on the BY wire when the speed switch is in the high position so you have some trouble there. Since there is only 5 volts on the connector without a load the relay is most likely bad. You should see 12 volts at that point with, or without a load. Quote Link to comment Share on other sites More sharing options...
ivans imports Posted February 17, 2012 Share Posted February 17, 2012 u can sub in a headlight relay in place oops sorry heavy black and red and heavy orange(red) and yellow I have the whole harnass on the ground if you need any more answers Quote Link to comment Share on other sites More sharing options...
Mikevan10 Posted February 27, 2012 Author Share Posted February 27, 2012 I managed to find the heater blower relay yesterday! And with some difficulty I also managed to unplug its connector. I then attempted to pop the relay off of its mounting bracket but only succeeded in breaking the relay housing and it all fell behind, I think, the fuse box and will not be retrieved. Anyway, the connector is still WAY up under the dash and barely within finger tip reach. So it is not going to be easy to run an experiment where I short circuit the RY and RB wires to see if the blower motor comes on. I will try to do this but it will be difficult. Will I have to buy a new genuine Subaru relay from the Subaru dealer or is the connector some kind of a standard configuration such that I can buy a generic relay (headlight?) at NAPA our AutoZone, for example? Thanks, MIke V. Quote Link to comment Share on other sites More sharing options...
Cougar Posted February 28, 2012 Share Posted February 28, 2012 You should be able to get one from NAPA. Quote Link to comment Share on other sites More sharing options...
Mikevan10 Posted March 4, 2012 Author Share Posted March 4, 2012 I picked up a general purpose relay today, but before installing it I did some more testing. I need some help from you electrical experts. Here's what I did. I unplugged the blower relay (as reported above). I connected a volt meter between the connector plug pin on the Red/Yellow wire and ground. This is the power feed wire from the fuse box. Got 12 volts. I pulled the two fuses out of the interior fuse box in the lower right hand corner of the box. These are labed "Heater" on the label inside the fuse box cover. I checked them both with an ohm meter. They both checked out good. I connected a test wire to the pin in the relay conector plug connected to the Red/Yellow wire and connected the other end of the wire to one of the pins on the blower motor. I connected the other pin on the blower motor to a known good ground. The motor did not respond. I then reconnected a volt meter between the Red/Yesllow wire and ground. 12V again of course. I then connected one pin on the blower motor to ground. When I connected the other pin on the blower motor to the Red/Yellow wire, the volt meter dropped from 12V to 0V. So if the blower motor is not in the circuit I have 12V on the Red/Yelloe wire but if I put the motor in parallel witrh the volt meter the voltage drops to zero. This should be telling to you electricians. I have my own theory but I'm not sure how to practically test it given the physical locations of everything. By the way, if I take my test wires and connect the motor across the battery terminals the blower immediately runs like gangbusters. Who has a theory? Thanks alot. Mike Quote Link to comment Share on other sites More sharing options...
Cougar Posted March 4, 2012 Share Posted March 4, 2012 (edited) Since the r/y power supply wire voltage dropped to zero volts when you placed the motor across the leads that means there is a bad connection to power on the r/y wire. When no load is placed on the wire no current will flow so the meter sees 12 volts on the wire. But when a low resistance is tied to it like the blower motor, current will then flow and all the supply voltage gets dropped across the high resistance in the series circuit, which is the bad connection. The circuit basically sees the motor resistance just as a connection to ground. Check wire connection at the fuse panel for a problem. Hopefully the trouble is there. If it isn't there then perhaps there is a connector involved that has a bad connection. Edited December 18, 2013 by Cougar Quote Link to comment Share on other sites More sharing options...
Mikevan10 Posted March 4, 2012 Author Share Posted March 4, 2012 Cougar, the electrical wizard, had it right. Long story short, the power input connection at the interior fuse box was dodgey. Alot of work, skinned knuckles, a broken relay and a bunch of time for what turned out to be a bad connection at a relatively accessible plug connector! Thanks to those who commented here. Mike Quote Link to comment Share on other sites More sharing options...
Cougar Posted March 5, 2012 Share Posted March 5, 2012 Hopefully you didn't skin the knuckles too badly. Thanks for the update and glad you found the trouble. Quote Link to comment Share on other sites More sharing options...
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