Need FAN FAIL warning light help

[Hank]

I noticed earlier this summer that I was getting a "Coolant Fan Fail" warning light. I have Fanzilla. Last time I was at PJ Grady's, I bought a replacement otterstat, which I replaced this morning, thinking that was the source of the problem.

I replaced the otterstat no problem (lost about a cup of coolant--more on that later). Anyway, I started the car up after sitting for a couple of months and let it warm up. It got up to 220 degrees and the fans did not come on. I flipped on the A/C and the fans came on, along with the FAN FAIL light a few moments later. I turned off the A/C and the fans turned off. But here's the weird part -- I turned the A/C back on, and the fans and FAN FAIL light came on, but the fans started cycling on and off with the compressor. I always thought they stayed on the entire time the A/C was on. So clearly I've got some problem -- does this sound like anything common I can fix? Is it possible that Fanzilla went bad?

About the coolant loss, as I said, I lost about a cup of coolant during the otterstat change. I do have the self bleeder at the top of the engine, but might I need to bleed the lower radiator too now? And could that be contributing to the problem, even though I got the FAN FAIL light earlier this summer before I changed the otterstat?

Any help or advice would be most helpful! I'm showing the car tomorrow to a prospective buyer.

Thanks,
-Hank

#1619

[Chris4099]

First, the fans cycle with the compressor, so that is normal. The only time they would stay one while the compressor cycles would be if the otterstat is keeping them on from the coolant temp being high.

As for the fan fail light, I believe the Fanzilla lights it when it detects one of the fuses has blown. So pull out the two glass fuses in the Fanzilla module and verify they are good. If so, next verify both fans are on when the engine warms up or the AC is on. If both fans are good, then there could be an internal issue within the Fanzilla causing it to falsely turn on the light.

As for the coolant loss, a cup of coolant is no big deal. The radiator should be able to purge out that small amount of air with no issues. It's only when you drain and refill the whole system do you need to manually purge that out.

[David T]

The fans come on when the ignition switch is on under two conditions:
1) the otterstadt switch closes on temp rise
OR
2) the A/C compressor clutch is engaged.
#2 sounds OK but for #1 either the otterstadt switch is bad or the wiring to it is not right.
For the Fan Fail light, one fan is not running. Possible causes include:
Bad fan motor
Blown fuse in Fanzilla
A problem with the wiring between the Fanzilla, the motor, and ground.
Most common problem is worn or stuck brushes in the fan motor.
David Teitelbaum

[Chris4099]

David,
When I ran the Fanzilla, I confirmed that it only turns on the fan fail light when a fuse is blown. It will not monitor the fan in any way. In my case, I had a connector in the relay socket push out causing one of the fans to not get power. No warning light. But if I pulled either fuse out, the light would turn on.

I completely missed the part about the fans just not turning on when the engine temp was above 200. I agree, either bad switch or bad connection at the switch. He should jump the two wires together to confirm the wiring is good. If it comes on, sounds like either there was a bad connection or the switch itself was bad.

[DMC5180]

I used to have Fanzilla. I've experienced the light coming on twice. Both times one of the twist lock fuse holders had fallen out. I never really determined how they could have popped out. Perhaps moving components around accidently bumped it loose. This is also how you test the FAN FAIL light. If either fuse is removed or blown, it will illuminate the fail light. Flashing on/off with a/c compressor or on continuously with the otterstat cycled on.

If the fail light comes on, it means one of the fans is not running. This is why you hear A fan running with the light. So check that the fuse holders are in place. If so and you have a blown fuse, look for a frozen fan motor or dead short. The easy way to determine if it's a bad motor or short is to unplug the fan connector from the inop motor. Replace the fuse and turn on the A/C. If the light stays out GOOD Fuse, its the motor. If the fuse blows its a short in the wiring.

[Hank]

Thanks for all your replies.
I checked the fuses, and one fuse had some rust/corrosion, so I cleaned that up and the light seems to have gone away for now. I have not yet confirmed if both fans are running with or without the otterstat shorted out -- I'll check them both tomorrow.

But I think I might have a bigger problem -- look at my fanzilla unit!:

521052085209

I don't think it came that way from Bob Zilla. But it seems to still be working (mostly, I think).

[DMC5180]

That is a familiar look. My unit did the same thing. Not quite that bad though. It has always worked, even with the melted case.

btw: sorry to see your selling the car, be sure to tell the new buyer about the forums. Newbies are always welcome, that's what we are here for. What are the last 5 digits of your VIN? Manual or Auto? Black or Grey int? Hood style: Flap/no flap, lines or no lines ?

[Bitsyncmaster]

Thanks for all your replies.
I checked the fuses, and one fuse had some rust/corrosion, so I cleaned that up and the light seems to have gone away for now. I have not yet confirmed if both fans are running with or without the otterstat shorted out -- I'll check them both tomorrow.

But I think I might have a bigger problem -- look at my fanzilla unit!:

521052085209

I don't think it came that way from Bob Zilla. But it seems to still be working (mostly, I think).

Mine had a little heat warping but not as bad as yours. It's the heat produced by the relays inside the fanzilla and the heat in the relay compartment on those hot summer days.

[Hank]

What are the last 5 digits of your VIN? Manual or Auto? Black or Grey int? Hood style: Flap/no flap, lines or no lines ?

#1619 Black, Flap with lines. Manual. See: http://eskin.com/delorean

I did recently replace the seats with the two-tone Houston seats. I like them alot.

[DMC5180]

I like those seats too. It's on my list to do someday.

Also which type A/C panel Decal do you have.? look at this post http://dmctalk.org/showthread.php?1640-HVAC-panel-Ouline-vs.-Solid-Lettering-VIN-cut-offs&p=20511&viewfull=1#post20511

[Hank]

Also which type A/C panel Decal do you have.? look at this post http://dmctalk.org/showthread.php?1640-HVAC-panel-Ouline-vs.-Solid-Lettering-VIN-cut-offs&p=20511&viewfull=1#post20511

I'm pretty sure I have #5.

edit: yup:

5211

[DMC5180]

Good to know.

[Hank]

Well, I shorted out the otterstat, and only one fan came on. So despite the fact that Fanzilla doesn't indicate a broken fan with the Fan Fail light, its corroded fuse did it instead.

Is it OK to run with only one fan in the fall? It's in the 60's today. I'll get it fixed asap ("Hello, Rob?")

[DMC5180]

As long as you don't need A/C you should be Ok. One fan is better than no fan. When I first bought my car I was unaware I only had one working fan. One of the blades had come off the motor, both motors ran though. I also never used the A/C in the first 6 years of ownership. Normal highway driving doesn't use the fans hardly at all. Stop & go does, but that just means it will take a little longer to bring the temp down with the otterstat switch. It should not hurt anything short term. Thats one reason you have 2, for insurance.

[Chris4099]

Well, I shorted out the otterstat, and only one fan came on. So despite the fact that Fanzilla doesn't indicate a broken fan with the Fan Fail light, its corroded fuse did it instead.

Still sounds like your otterstat is bad and should be addressed too before driving it. Just to confirm, was the otterstat pointing up or down? When it's pointing up, air gets trapped there and keeps it from turning on. So if yours is like that, rotate the pipe so it points down and that may fix that problem.

[Hank]

Still sounds like your otterstat is bad and should be addressed too before driving it. Just to confirm, was the otterstat pointing up or down? When it's pointing up, air gets trapped there and keeps it from turning on. So if yours is like that, rotate the pipe so it points down and that may fix that problem.

It's pointing down. It's also brand new. Not that means it's working for sure, but I doubt the new otterstat is failing.

[DMC5180]

My otterstat does not switch the fans on till I get to 220 also. Who nows how accurate the gauge is. I use it as reference only. The otterstats are not 100% accurate and do have a +/- 5% tolerance range. If the original DMC unit spec is ON at 207℉ + 5% is 217.3

[DMC5180]

OOPs Accidental duplicate post Deleted