no blower fan September 18, 2009, 09:07:23 PM After some searching, looks like no fan speed at all, is a switch prob, not the thermal resistor. Anything else to check?? Quote Selected
no blower fan Reply #1 – September 18, 2009, 10:12:19 PM check dedicated fuse 9 for blower, AC and ATC Quote Selected
no blower fan Reply #2 – September 18, 2009, 10:16:24 PM My guess would be switch or fuse, but MAYBE a motor. If you turn it to high speed, and it doesn't come on, either voltage isn't getting to the switch, or the switch ain't letting the current through. Can't remember if these are three-speed or 4 speed fans (never took real notice), but either uses the same principle. Low speed, all resistors in series with the armature of the fan motor. Middle speed, bypass one resistor. Next speed, bypass one more resistor. High speed, bypass all resistors, fan motor running with full battery voltage applied. Oh yeah, OFF, open the circuit. ;o) Never had this problem on any vehicle, so don't even know how hard the resistors are to get to on these cars. But, if you're already there, turn the switch on, and check for voltage to ground at the resistors. If you have it there, you've got a bad motor or broken wire between the resistors and the motor. Stuff happens. Quote Selected
no blower fan Reply #3 – September 18, 2009, 10:45:34 PM ............................super easy to get to....http://www.foxtbirdcougarforums.com/showthread.php?p=220320#post220320http://www.foxtbirdcougarforums.com/showthread.php?t=17041===============================================Blower Motor HVAC only runs on HIGHZERO DOLLAR FIX**warning, after this repair, do not touch internal parts, BURN HAZARD***Remove the glove boxlocate the resistor mounted in the air box to the leftIt will have one connector and is mounted by two screwspull it out and stare at it real closethere will be small springs mounted to clipsThese springs are the resistors which limit fan speedThere will be another tiny tiny device that looks like a electronics partThis would be a fuse and you will remove it nowInsert in a section of 30awg wire or smaller in place of the fuseThis thin section of wire will act as the "new" fuseTest fanall speeds should workWhen debris gets built up inside the fan causing it to be "heavy", the fuse will blow again.============================================== Quote Selected
no blower fan Reply #4 – September 18, 2009, 10:57:15 PM for you old painthttp://s47.photobucket.com/albums/f162/jcassity_bucket/ Quote Selected
no blower fan Reply #5 – September 18, 2009, 11:01:26 PM Quote from: jcassity;291734for you old paint http://s47.photobucket.com/albums/f162/jcassity_bucket/ You are THE MAN!!! I'm assuming there's very little difference in the 86 and 87 other than the header panel and headlight circuits? That's about to get turned into a large PDF!!!! Quote Selected
no blower fan Reply #6 – September 18, 2009, 11:51:50 PM most of our basic wiring is either the same or just simple color code cyphering. Quote Selected
no blower fan Reply #7 – September 19, 2009, 09:26:47 AM I just checked it further, the fan moves very low, maybe low speed, on all settings.Must be the switch messing up?update. I just tore into the selector panel, non ETC btw, I havent gotten the switch out yet, but the connector for the switch is completely and totally melted. How does the circuit get that HOT? Switch bad?, resistance in the motor? If I get a new connector, how do I transfer the wires and keep this from happening again?Mike Quote Selected
no blower fan Reply #8 – September 19, 2009, 10:42:54 AM Sounds like you need a new Fan motor. That pigtail gets that hot due to a bad connection or high resistance in the circuit. To keep this from happening again you need to make sure everything is right with every piece from the switch to the motor. Sounds like I would plan one a new fan along with a new pigtail for the switch. As far as transfer of the wires the new or JY pigtail will have Extra for you to cut yours off and splice in the new one. If you have to just do it one wire at a time to keep them all in order. Stuckman Quote Selected
no blower fan Reply #9 – September 19, 2009, 07:02:29 PM The black (ground) wire to the switch was very corroded, guess that could cause overheating of the wires? I would think a fuse would have blown if the motor was causing that much load? Quote Selected
no blower fan Reply #10 – September 19, 2009, 08:40:17 PM Quote from: mcb82gt;291811The black (ground) wire to the switch was very corroded, guess that could cause overheating of the wires? I would think a fuse would have blown if the motor was causing that much load? Actually it doesn't take a whole lot of current to produce a whole lot of heat. Ever touch a 100W light bulb while it was on? That's only drawing about 1 amp at 120V. Now, calculate the power that could be dissipated in that switch. Let's say you have 0.01 ohms resistance in that switch, or on one of the connectors. P=I^2*R. I = approximately 15 A on the fan motor. Therefore, P=~2.25 W. Not so bad, but let's say the resistance goes to 0.1 ohms, and it might when the connection gets warm. Now we're talking 22.5 W dissipated somewhere. Unfortunately, the only thing to absorb the heat is the plastic, which lets the connection get loose when the plastic deforms. Guess what, the resistance just went up some more. If it gets up to 1 ohm, now we're talking 225 watts. That's gonna start really melting things and making a big mess. The switch itself has grease inside it, and after 21 years of being turned on and off, there's probably a lot of carbon/crud contamination causing a poor connection inside the switch. Once the contacts IN the switch get hot, they'll heat up the terminals (connectors) and cause them to get loose. Chances are, you're not going to salvage that switch, so replacing just the connector might be a waste of time and money. Replace the switch AND the pigtail. Meanwhile, we've never exceeded 15 A. THAT's why the fuse didn't blow. It won't blow unless the current goes above the fuse rating. It might eventually when there's enough carbon from the burning switch for it to track straight across from hot to ground. The reason the motor was running so slow now is because most of the voltage drop is across the bad switch. Total apparent impedance of the circuit at 15A would be approximately .80 ohms, when everthing is in good shape, with probably less than .01 of that being across the switch. Now, let the switch get up to 1 ohm, and your current draw would be somewhere around 8 Amps, with 8V drop across the switch, and the other 4 across the motor. This is the very reason manufacturers put some kind of "dielectric" grease in the connectors. The grease isn't there to conduct electricity. It's to prevent corrosion. When you get your new switch, pick up a small tube of white lithium grease. White, because it's easier to clean up than black, lithium, well because it's lithium. Very stable stuff, never gets hard. Same stuff used for heat-sink applications. Use a Q-tip to swab all the male connectors with the grease, and then put a little in the ends of the female connectors. Slide them together, and bingo, you'll have a corrosion free connection. The grease will help with making the connection easier to plug in too. You may want to go find a pig-tail harness in a yard and clip it out leaving enough wire to splice into your harness if the plug is severely damaged. Chances are, the tempering is burned out of the connectors in that, and they'll never stay tight again. Or, you could get a part number for a NEW pig-tail from BWD at these links: http://www.bwdautomotive.com/Online%20%20Catalogs-eCatalog/Content.aspx http://www.bwdautomotive.com/Online%20%20Catalogs-eCatalog/Content.aspx You'll probably have to get your favorite parts house to order these for you, albeit the switch may be hanging back in the electrical section. Fairly common switch. Quote Selected
no blower fan Reply #11 – September 20, 2009, 01:37:15 AM Now that is a response..... Increasing the resistance in the ground wire, causes a increase in the power wire to perform the same function??I was going to go to the yard tomorrow. I have to get a new harness connector, mine is totally melted beyond recognition.I was going to get the wiring plug and a length of wiring. The switch is really overheated also. If I dont find a "good" switch in the yard, I will pick one up from the parts store.I cant seem to understand why the ground wire would be so corroded, while all the other wires were fine? Maybe over time the switch got hot and caused the ground wire to slowly lose a good connection, and then it just escalated from there?? Quote Selected
no blower fan Reply #12 – September 20, 2009, 03:09:59 PM Quote from: mcb82gt;291869Now that is a response..... Increasing the resistance in the ground wire, causes a increase in the power wire to perform the same function?? That's not what I said. Increase the resistance of the total circuit, the current will decrease. But, a small resistance will make for some serious heating. 15A x 0.1 ohm only gives you a 1.5v drop. But that same 1.5V drop equates to 22.5 Watts heat dissipation. Quote from: mcb82gt;291869I was going to go to the yard tomorrow. I have to get a new harness connector, mine is totally melted beyond recognition. I expected no less. Quote from: mcb82gt;291869I was going to get the wiring plug and a length of wiring. The switch is really overheated also. If I dont find a "good" switch in the yard, I will pick one up from the parts store.Good plan. Quote from: mcb82gt;291869I cant seem to understand why the ground wire would be so corroded, while all the other wires were fine? Maybe over time the switch got hot and caused the ground wire to slowly lose a good connection, and then it just escalated from there?? If you can read electrical diagrams, this would probably help understand why that wire would get the hottest. (borrowed from jcassity's photobucket) That is the high speed setting, which would have the most current through it, and is probably the most common speed setting you use. What's the first thing you do in the summer? Crank the fan WAO to cool the car down. In the winter? Crank the fan WAO to warm the car up. Defog/Defrost the windshield? Crank the fan WAO to quickly clear the windshield so you can see where you're going. One of two wires in the high speed circuit across that switch would be your most vulnerable point. My guess is, there's a cleaner connection inside the switch between the incoming wire and the contacts. The real problem may have started inside the switch. The contacts in the switch may have caused the poor connection on the outside, which simply made it escalate. Quote Selected
no blower fan Reply #13 – September 20, 2009, 06:53:08 PM Got a used switch from the yard, along with the wiring. Put it all back together and it works great. Thank you very much everyone, and NO I cant read a wiring diagram to save my butt. LOL Quote Selected
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