What's burning out the radiator fan relay, 98 Grand Voyager 3.0?

When we bought the van a few years ago, the check engine light was on. The diagnostic at AutoZone indicated possible fan relay, among other
things I had to fix. Replaced the relay, fans worked fine for 3 months, Same thing, got a relay from a dealer this time, 3 months or so, I'm replacing it for the 3rd time. What's causing it to burn out? The plastic on the connector at the pin 1 ( ? ) contact is a bit melted. Help! These relays ain't cheap... Mark Goodall
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On 9/4/2011 8:40 PM, mark wrote:

Yes, they are pretty cheap. Like $12. But it is the fan that is throwing the voltage out of whack. It's easier just to use the single speed fan than replace all.
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It appears it's not the 'relay' this time. I replaced it ($58) and the fans wouldn't work, running the van up past normal temp. I should have known, because last time the check engine scan threw a code for it, and this time it didn't. As Daniel indicated, it's not a relay, so I don't think I can check it with a VOM. The fans run fine straight off the battery (although one fan has a bit of resistance when I turn it by hand)so I'm thinking about wiring them to the battery and fuse box so they only run with the key on. I think the fan wires are green & black, anyone know the polarity so they spin the right direction? Mark Goodall
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Mark Goodall wrote:

You might was well connect the fans directly to the battery (or to the switched 12V bus that becomes active when-ever the ignition is on).

You need to oil or lubricate that fan - or replace it. That sticking fan is drawing more load from your electronic relay, which is causing your relay failure.

But you need to lubricate that fan so it turns freely, otherwise it will eventually fail.
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Thanks Mopar Man, how do I know I've got the fan polarity right? Blowing toward the engine? Mark Goodall
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Mark Goodall wrote:

Well, first of all I would expect that one lead of the fan motor is already connected to ground - because there's no need to switch BOTH leads of the fan motor - just the hot or +12V lead.
If that's not the case, or if you can't identify the switched or hot lead, then yes, the fan normally pulls (or pushes) air from the front of the car through the radiator towards the engine block.
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green is hot, black is ground but I'd just replace them. save you a lot of headaches and they will last another 13 years or more.
It appears it's not the 'relay' this time. I replaced it ($58) and the fans wouldn't work, running the van up past normal temp. I should have known, because last time the check engine scan threw a code for it, and this time it didn't. As Daniel indicated, it's not a relay, so I don't think I can check it with a VOM. The fans run fine straight off the battery (although one fan has a bit of resistance when I turn it by hand)so I'm thinking about wiring them to the battery and fuse box so they only run with the key on. I think the fan wires are green & black, anyone know the polarity so they spin the right direction? Mark Goodall
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On 9/4/2011 8:04 PM, ng_reader wrote:

Not from Mopar or an after market discount store. Are you buying them from a junkyard?
But it is the fan that is throwing

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Thanks, Mopar Man. And PaxPerPoten, check out this fan test: http://troubleshootmyvehicle.com/jeep_fan_relay_4.0L_4.7L/fan_relay_test_6.php I ran the test with my multimeter, passenger side fan showed about 10 amps, driver side fan 62 amps! Does this test sound kosher? I didn't know you could test potential current draw with just an ohm-meter. If so, could I have fried the new PWM relay before the fans tried to spin? I read the whole article, but I can't check the 'relay' because I don't have a 'generic scanner' and probably wouldn't know how to use it. Would Advance or Autozone be able to test the relay? I just spent big bucks on the relay, so if it's fried they'll replace it, but if it's okay I'll keep it, replace the fans, and keep troubleshooting. By the way, I'm a 53 year old audio engineer, so I'm a little green when it comes to working on cars. Thanks a whole lot, guys
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Hey PaxPerPoten, (is that Latin?) ng_reader was the one who said "yes they are cheap, like 12 bucks" Not at Advance, it was about 58 bucks. Check out my previous post. I guess I'll call Advance & Autozone to see if they can check the PWM relay. I kinda doubt that they can. Mark
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On 9/5/2011 11:21 AM, Mark Goodall wrote:

cheap, like 12 bucks" Not at Advance, it was about 58 bucks. Check out my previous post. I guess I'll call Advance& Autozone to see if they can check the PWM relay. I kinda doubt that they can.

Simple..Take it back..And then buy another one elsewhere..Or just buy another one and when fixed take one back. $58 is about right. After all it is a solid state relay that manufactured for 58. So that markup sounds about right. ;-p It had to travel first class from China.
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replying to Mark Goodall, Matt Attack wrote: There are mechanical relays , and then there is the solid state relay. the mechanical ones are the 12 doller ones , the solid state one is better part of 60 bucks
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I didn't get the original question, just the followup -- but if you're losing fan relays with any regularity, and there isn't something exposing them to the elements, I'd start wondering if there was a problem with the fan motor that was causing it to draw too much current (not enough to blow the fuse, but enough to shorten the life of the relay contacts).
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On 9/5/2011 11:06 AM, Mark Goodall wrote:

driver side fan 62 amps! Does this test sound kosher? I didn't know you could test potential current draw with just an ohm-meter. If so, could I have fried the new PWM relay before the fans tried to spin? I read the whole article, but I can't check the 'relay' because I don't have a 'generic scanner' and probably wouldn't know how to use it. Would Advance or Autozone be able to test the relay? I just spent big bucks on the relay, so if it's fried they'll replace it, but if it's okay I'll keep it, replace the fans, and keep troubleshooting. By the way, I'm a 53 year old audio engineer, so I'm a little green when it comes to working on cars.

R/V=A Not a very accurate way to measure current. The very best is still a DC current meter and the fan running. You can also use a clamp around the wire device that is hooked to a DC Current meter rather then an in line system. A clamp current detector can also be used on your "O" scope.
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Mark Goodall wrote:

http://troubleshootmyvehicle.com/jeep_fan_relay_4.0L_4.7L/fan_relay_test_6.php
I wouldn't even think that 10 amps is normal, let alone 62 amps.
In doing some web-searching, I've come across references where people pull electric fans out of junkyard '89 Taurus to put into '94 Mustang:
http://www.fordmuscle.com/archives/2003/02/electricfan/index.php
They measure the current draw of the motor at 40 amps using the "high-speed" supply wire.
That is a single large motor/fan. I would guess that if you have a setup using multiple smaller fans, that the individual fans will draw a smaller amount of current, but maybe collectively you're still looking at 20+ amps worth of draw.
I wouldn't have thought that the current draw for a car's electric radiator fan (or fans) wouldn't have exceeded 5 or 10 amps in total, but it appears that they might very well do double or 4 time that amount. And if so, I really have to question the over-all energy efficiency of having electric fan motors vs a mechanical fan turned directly by the engine.

That seems like a really hokey way to test the current draw of a DC motor - by measuring it's zero-RPM resistance. That would probably tell you what the starting current is for the motor, but not the running current (starting current is always higher). When a motor is running, it's creating a "back EMF" voltage that reduces it's current draw - but that's a function of it's RPM. If your fan is gummed up and doesn't turn freely, then your RPM will not be what it should and your current draw will go up.

Or even if your fans do spin, they have too much mechanical resistance that over hours or days of operation will burn out your controller.

Take the fans apart, or spray a lot of WD-40 into them and get them spinning easily by hand, then hook them back up directly to the battery (to make sure they spin nice and easy and fast) and then hook them up to the relay / controller and see if they spin when the engine is running (the engine might have to be hot for the fans to come on).
If you use WD40, then I'd spray something else into the fan after (a true or real lubricant, like maybe a silicone spray). WD40 is more of a solvent / cleaner than it is a lubricant.
You might also want to look at this:
http://autorepair.about.com/library/a/1f/bl287f.htm
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This is a WAG (wild a**ed guess) but check the current drain on the fan. I expect that it's marginally just below failure and the added current is melting the relay housing.
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They aren't relays at all, the rad fan on 3rd generation Chrysler vans are all variable speed and what they call a "relay" is actually an electronic PWM motor speed controller with a big power MOSFET in it. If it is overheating the fan is likely overamping or the "relay" might need to be bolted to something that is better at getting rid of heat, like an old computer CPU heatsink.
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I just looked on fleabay and noticed that the ones for the 4th gen vans have a PGA (pin grid array) heatsink on the back, kind of like, you guessed it, a CPU (processor) cooler heatsink. It would appear Chrysler learned something and quietly made a change.
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It appears it's not the 'relay' this time. I replaced it ($58) and the fans wouldn't work, running the van up past normal temp. I should have known, because last time the check engine scan threw a code for it, and this time it didn't. As Daniel indicated, it's not a relay, so I don't think I can check it with a VOM. The fans run fine straight off the battery (although one fan has a bit of resistance when I turn it by hand)so I'm thinking about wiring them to the battery and fuse box so they only run with the key on. I think the fan wires are green & black, anyone know the polarity so they spin the right direction? Mark Goodall
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Yes it did throw the code for rad fan pwm relay - the Advance Auto guy wrote the code down and wrote something about exhaust emission control (wrong) I looked it up at home and confirmed it at Autozone. Mark
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