Blew another 50amp fan fuse! HELP!

[stprorolla49]

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!

[wmburns]

What happens when the fan motor is spun by hand? How do the bearings feel?

What are the Ohm readings across the two speeds?

Honestly, if you can't find a wiring fault, more than likely this is a bad fan motor.

[KanuckiStang]

Originally Posted by wmburns

What happens when the fan motor is spun by hand? How do the bearings feel?

What are the Ohm readings across the two speeds?

Honestly, if you can't find a wiring fault, more than likely this is a bad fan motor.

+1. Start by spinning the fan by hand. If it's tough to spin it's likely the problem.

[WrenchThrower]

Bad fan capacitor maybe?

[Michael Yount]

The long term fix is to get the big amp-vampire fan on a variable speed/variable current/soft-start controller - instead of a switch/relay.

[JohnC76]

I've been through this over the last 2 summers now. When it got really hot, over 100F, I blew the fuse twice within 3-4 weeks where the first summer it only blew once.

I replaced the CCRM and I've not blown the fuse again, but I really think it hasn't solved the problem. I think the weather cooling to the 80-90's has masked the issue.

Seems when I run my AC on MAX with hi fan speed, when I come to a stop, I can watch my battery gauge start to slowly go down.

That is what it was doing every time it blew the fuse. I had just came off the interstate and stopped at a red light when my battery gauge started to pull all the way down to the "N" no normal and then my ac quit cooling and my car engine temp started to rapidly rise. This was with the AC on max with hi fan speed.

So I'm holding out saying the CCRM is the fix for now. I recommend you check your fan and go from there.

[CodyNelson]

I was having this problem just a couple days ago. It ended up being that my fan blade was cracked and it was causing the blade to drag on the housing. This extra resistance was causing my fuse to blow

[blckstng96]

i have had these fans work intermittent before.its prob working til it overheats bc its straining then heating up pulling those amps blowing the fuse.id try a fan.

[stprorolla49]

UPDATE:

The day after I posted this issue, I swapped the fan, low speed resistor, and fuse out for new ones. 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 intermittent 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?

[Chrm97PI]

is the car overheating?

[LS1KILR]

Ac compressor maybe

[stprorolla49]

Originally Posted by Chrm97PI

is the car overheating?

Nope, but only because I know how hot it will get on my autometer before it boils over. I shut it down right when I got back to work and it didn't overheat.

Very weird though, I left work, drove home and the low speed fan was working (only a mile drive), shut it off, left 15 minutes later for happy hour, got to the restaurant right before the high speed fan was about to come on and sat next to the fan. As soon as it hit 194, it switched to high speed and ran fine. I don't get it. Every other time this has happened it has blown a fuse. This time it didn't blow the fuse, then the next time I fired it up it worked fine.

As for the a/c compressor, what would be some symptoms of a bad compressor? It seems to work awesome and blow very cold. I do notice the idle rise and drop pretty frequently when the a/c is on max. Ideas?

[Chrm97PI]

low speed fan wont kick on till 195 ish, high speed kicks on around 220 iirc. ac compressors normally make some noise when the clutch is enguaged, and electric fan speed should be on high anytime ac is on.

[stprorolla49]

Originally Posted by Chrm97PI

low speed fan wont kick on till 195 ish, high speed kicks on around 220 iirc. ac compressors normally make some noise when the clutch is enguaged, and electric fan speed should be on high anytime ac is on.

Sorry I didn't clarify, when I had the car tuned, my tuner changed the fans for low speed to come on at 188 and high speed at 194.

Yea, I just went outside and fired the car up after it cooled off a bit, drove it until the fans were supposed to come on....and they did...

Still not sure what's going on. I did already know about the fans coming on when the a/c, and it should also come on when you unplug the coolant temp sensor. This is a very intermittent issue which really sucks because the car is my DD.

[stprorolla49]

SUNDAY UPDATE:

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 and WARM.

- 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. High speed also works when the car is COLD and I do the a/c on max test and the coolant temp sensor test.

THOUGHTS?! THANKS!!

[Chrm97PI]

try a new high speed fan relay.

[stprorolla49]

Originally Posted by Chrm97PI

try a new high speed fan relay.

Leaning towards this. Can the high speed fan relay be changed by itself, or do you have to change the whole CCRM. From what I understand, the relays are in the CCRM. Also, if I were to change the CCRM, would my fan settings that my tuner programmed change?

Does this have anything to do with my cycling a/c clutch or whirring sound? 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!!

[Chrm97PI]

you cant check resistance while there is a load on the circuit

[stprorolla49]

Originally Posted by Chrm97PI

you cant check resistance while there is a load on the circuit

Sorry, as I mentioned in my thread on another site, I am somewhat of an electrical n00b when it comes to diagnostics like this. I am just getting the hang of a multimeter. I have been doing this the last 2 days -->

Anyway here's an update:

Now its throwing PO118 code - Engine Coolant Temperature sensor. I figured, #### this controls the fans as well, so I replaced it. No dice, still have a CEL.

That was around 10 am.

About half hour ago, I 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. I tried to get the fan clip off to test the voltage on the wires but the car was hot and i burned the #### out of my arm on the rad hose and the blower. I hate electrical diagnostics!!!