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300SDL heater/AC blower fan not working and fuse diagram
I've researched the threads on this issue and here is where I am at...
Blower fan does not work at all on any settings. What I have done so far: 1. Diassembled blower from under dash and confirmed that it is working by applying 12 volts. 2. Checked for 12 volts at the wiring harness by blower - nothing. 3. Checked and replaced (intact) fuse #5. 4. Inspected 30A separate fuse on firewall; fusebox and fuse need replacing. Here is where I am at... when I inspected and found the bad 30A fuse (after verifying motor), I assumed it was the fault. I temporarily jumpered it to no avail. ***I am not even getting voltage to either side of the 30A fuse when the vehicle is running.*** Where should I look next? Is this fuse wired after the CCU and before the blower motor? In other words should I be looking at faulty solder joints in the CCU? (By the way, I do get heat, just no blower fan.) And also, is this thread correct for the fuse diagram for a 1987 300SDL(?): Fuse box chart, what fuse goes where (post #8, USA) If not, possibly someone has this? (Mine, of course, is missing.) Thanks, Andy
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1987 300SDL 2005 Ford Excursion 6.0L Powerstroke, 6" suspension lift |
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Issue SOLVED!
Please forgive me in advance, but this is a long post.
As you can tell by the dates of my original posting, it took me this long to finally get around to figuring out and correct my heater fan / heater blower issue. Yes, it's now officially cold weather here in New Hampshire... The issue has been resolved, but not what I would have originally figured it to be... As noted in my original post, I replaced, because it was blown and melted, the auxiliary fuse #15 (separate 30 AMP flat fuse). As many will note this was an add on item that upped the fan blower fuse amperage rating from (I think?) 25 AMPS (fuse in the fuse box) to the 30 AMP external (auxiliary) fuse in it's own separate fuse holder mounted on the firewall. I then checked fuse #5 for the CCU and rechecked fuse #15 for the fan (Thank you Brian Carlton!!! for helping me figure out which ones went to what.) Both were in working order (continuity wise) but unfortunately at this point, I still did not have 12 volts at fuse #15 (blower) but did have 12 volts at fuse #5 (CCU). I then 'ran up the wrong tree' and automatically thought it was a bad CCU. I got a used one off eBay to try, and still no go on the fan. I could hear the CCU trying to switch the pods when I actuated the main push button switches on both CCU's (and had my head down into the dash), so the issue was not the CCU. I remembered that I had purchased a Mercedes CD manual which had the wiring diagram. I traced the wiring back to the ignition switch. Two red 'hot' wires off the battery distribution switch were good to the ignition switch, but the pink / green wire that comes off the switch (that goes to fuse #15) that should have been hot with the ignition switch in 'run' position was not. Aha!!!... so I surmised a bad ignition switch, although there were NO OTHER IGNITION SWITCH RELATED SYMPTOMS!!! The car started fine, etc. I purchased a replacement ignition switch (replacement procedures listed below) and VIOLA!!! THE HEATER FAN RUNS AGAIN!!! ... and the 'fans' go wild...!!! (pun totally intended!) Here is the procedure I used to replace the faulty ignition switch (information copied from this thread: Ignition Cylinder, Switch, or Housing?, post #8) and edited: Removal and installation of a ignition switch for 1987 300SDL: 1) Extend telescoping steering to max out 2) Place front seat in most rearward position. (This is optional because if the seat if somewhat forward you can get closer to the dash. I am 5'10" and found it a bit challenging to sit on the front edge of the driver's seat while maneuvering. I actually got on my knees on the drivers seat for some of the acrobatic feats...) 3) Disconnect battery 4) Remove instrument cluster 5) Turn key to #1 (run position) and remove plug in back of switch (key position is required to "unlock" plug from switch) 6) While the key is in position #1, push ignition key tumbler release button in with a .050" hex wrench 7) Unscrew the black ring around the ignition key tumbler to remove (this is done with the hex wrench AND key in place) 8) Feel around (can't see due to angle) for Allen head bolt (5mm wrench if memory serves me) on top of ignition cylinder that mates with steering column and loosen (no need to remove) 9) Remove two bolts (13mm wrench) on top of steering column allowing column to drop 10) Look for ignition assembly "release button" that resides on lower right side of steering column where ignition assembly enters column. Position the steering column to the left and peer down on the lower right hand side of column. You'll see this release button as you look in between the column and the plastic trim piece that is attached to dash. You can push the button in with a small screwdriver to fully release the entire switch assembly. This took me a while to figure this out... The switch assembly will seem as though it wants to come out, but like it's stuck. NOTE: until this button is pushed in, you will not be able to slide the ignition switch assembly out of the column. 11) Orchestrate the complete assembly around to expose the back side of the ignition switch 12) Remove old switch (3 screws) from ignition assembly 13) For installation, reverse procedure. I had a bit of a bear of a time getting the key tumbler back in properly (because I turned the ignition switch while key tumbler was out). And make sure you have the switch in the correct position before attempting re-assembly. Remember the hex wrench and key must be in place to reassemble. The new ignition switch does not have the plastic 'T' that is in the original switch which required the key to be in position #1 for the plug to be removed. Others are correct that in using this procedure, one does not need to remove the steering wheel nor the lower kick panel. Sorry for the long post, but I figure this may be a good archive for the future... Cheers!
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1987 300SDL 2005 Ford Excursion 6.0L Powerstroke, 6" suspension lift |
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Good job Andy.
Thanks for the writeup on the switch replacement. I'll surely save it in my archives............ |
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