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08-10-2012, 03:43 PM #1
Keep blowing 50 amp fan fuses! HELP PLEASE!
When I put my blower together and got it tuned, a few days later the 50amp fan fuse blew. I traced the problem, replaced the 50 amp fuse and it has been good for over 2 months. The last week my a/c has been blowing non cold air occasionally, and today I was sitting on the highway in traffic and the temp gauge went to about 235-240. I shut it down and let it cool, checked the fuse and sure enough it was blown. I replaced the fuse, fired it up, the fan tried to spin and blew the fuse again.
I honestly don't know where to start, I've done a lot of searching but haven't found really what I'm looking for. Suggestions would be awesome, thanks!
2001 DHG Bullitt - #4113
NECA Member #10
Paxton Novi 2000, 3.25" pulley, CXRacing FMIC, Vortech MiniRace BPV, Aviator pump, 39lb Cobra inj, KB 20amp BAP, VMP HPX MAF, Borla Stingers, Bassani catted x-pipe, MM c/c plates, MM front coilovers w/Hypercoil 250lb springs, Bilstein HD's, Built '03 Cobra IRS, FRPP 4.10 gears, FRPP diff cover, MM subframe/diff bushings, RotorPros rotors & Hawk PC pads, 18x9 & 18x10 Bullitts, 265/315 R888's
404 rwhp / 398 rwtq - tuned by Kevin Hand @ Wicked Motorsports
2001 Silverstone Metallic Jeep Cherokee Limited
08-11-2012, 12:22 PM #2
Check the 3 pin plug going into the radiator fan motor. These cars like to melt them... and they ground out. Causes the fan to either blow the fuse to kills the fan motor itself (which can also lead to popping the fuse). Based on your description, I'd guess that's what is going on. When mine went, I just hardwired it myself instead of buying another connector.1998 Roush: M112 - Cobra short block - T56 - 1 of 1 made.
1999 C-SVT: Suspiciously stock-ish
1970 Mach 1: Resto-modded 351W
2000 Roush #5004: World's First M112'd V6 Mustang - Sold but not forgotten
08-11-2012, 06:03 PM #3
I checked that this morning and it looks perfectly fine. I also jumpered the motor and it seems as if both low and high speed work ok, but I spoke with Kevin my tuner today and he said the fan is probably going bad which would create more resistance on the circuit and blow the fuse. Makes sense to me, I'm probably going to just replace the fan and the fan resistor to rule those out. Wiring also looks fine. Not sure what's next!
08-11-2012, 06:26 PM #4
Seems like a smart step. The fan assemblies are easy to swap out, takes less than 15 minutes.
08-12-2012, 01:37 PM #5
- Join Date
- October 2011
- Concord, CA
You should be doing an ohms check on the motor not voltage check.
08-12-2012, 10:51 PM #6
Thanks fellas, I'll report back tomorrow with progress once I get the fan.
08-31-2012, 12:33 PM #7
I swapped the fan, low speed resistor, and fuse out. It ran perfectly for the last 3 weeks, sitting in traffic on 90 degree days, etc. Now today randomly the fans quit and the fuse IS NOT BLOWN! Also, with the a/c on there is a SLIGHT whirring noise coming from the engine bay.
I am getting sick of this issue and throwing money into the car to try and fix this. Does anyone else have any more suggestions?
09-01-2012, 10:35 AM #8
Did you do the wiring connector to the fan as well?
09-01-2012, 02:47 PM #9
Last edited by ninety5fiveoh; 09-01-2012 at 02:50 PM.
09-02-2012, 02:55 PM #10
OK, so let me outline where I am currently at to see if this helps. I also made a little headway on diagnosis:
- I start the car cold, fans are obviously not on.
- I turn the a/c on MAX (car still cold), and the fan comes on as it should.
- I shut the a/c off, fan shuts off.
- With the a/c off, car still cold, I unplug the coolant temp sensor on the intake manifold, fan turns on.
- I plug the coolant temp sensor back in, fans shut off.
ALL IS NORMAL AT THIS POINT.
- Wait for car to get to ~188 deg where the tune calls for the low speed fan to come on, which is DOES.
- Low speed fan runs fine until 194 deg where the tune calls for the high speed fan to come on which is DOES NOT and the fan shuts off completely.
- At this point I checked the 50 amp fuse in the main engine fuse box and it is NOT blown.
LET THE CAR COOL FOR 5 MINUTES.
- Fired the car back up at ~188 deg where the low speed fan should come on which it DOES.
- 30 seconds later when the car gets to 194 deg when high speed is supposed to come on, it does NOT and the fan shuts off completely.
- At this point, turning on the a/c on max does NOT turn the fan on, nor does unplugging the coolant temp sensor.
LS1KILR mentioned the a/c compressor might be going south so I tested that as well with the car COLD.
- With the car running, I turned the a/c on max, and unplugged the sensor mounted on the a/c line directly underneath my powerpipe. The compressor kicked off. I plugged the sensor back in and audibly heard the compressor kick back on.
-With the sensor plugged in, I also jiggled it back and forth, up and down as much as I could to see if there was any sort of continuity issue with that plug which there was NOT.
At this point, from my testing, clearly the wiring to the fans is ok because low speed works all the time, and high speed HAS worked for the last 2 weeks, then only worked intermittently over the last 2 days.
Last edited by ninety5fiveoh; 09-02-2012 at 03:03 PM.
09-02-2012, 04:44 PM #11
I just checked the ground wire going to the fan, because from what I have read, both the a/c high pressure switch and the fan run off the same ground. Resistance on 200ohm setting on my multimeter was between 15 and 17 with the fan working.
I tested this by turning the car on COLD, turning on the a/c to verify low speed fan was working, unplugged fan clip, and tested resistance on the ground wire.
Even though resistance is high (Haynes manual says it shouldn't be higher than 5), I don't understand why the low speed fan would still work since both low and high speed run off the same ground wire.
Tomorrow I will test both power lines for low and high speed fans. It is now raining...FML! I want this car fixed!!
09-03-2012, 11:38 AM #12
Now its throwing PO118 code - Engine Coolant Temperature sensor. I figured, shit this controls the fans as well, so I replaced it. No dice, still have a CEL.
EDIT: Went for a rip to blow off a little steam, and when I came back, the high speed fans were working with the a/c on and the car was at around 200 deg. I shut it off, turned the a/c off, turned it back on, the fans were still working and the CEL was gone. Since I changed the ECT sensor, I had cycled the ignition about 5-6 times. Would that have cleared the code in the car? The factory temp gauge works fine, FWIW.
NOW, this has happened before with the fans working then not working the next day, but maybe the ECT sensor fixed it. Who knows, I hate electrical diagnostics!!!
Last edited by ninety5fiveoh; 09-03-2012 at 01:16 PM.
09-03-2012, 02:11 PM #13
Electrical problems are the worst..did u clear the Ck engine light after u put the sensor in? Just replacing the part wont just shut off the light
96 GT convertible PI headswap and some bolt ons
Tuned by PSI Motorsports---294rwhp/292 rwtq
09-03-2012, 03:48 PM #14