Fan Relay (R6029) stops working

Tiny
MARK PATTERSON
  • MEMBER
  • 2006 DODGE CARAVAN
  • 3.3L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 158,000 MILES
Three month ago I have replaced the engine cooling fan assembly and the fan relay which fixed the problem of the fans not coming on when it gets really hot. However since then, in the span of 3 months, I have gone through 3 fan relay's (R6029). When it stops working the fan's won't stop spinning even after the van is turned off and cooled down. It will eventually drain the battery. I have another R6029 to install but I have to figure out why they keep going bad. I'm assuming there is a short or they are getting too hot maybe? How do I troubleshoot this issue?
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Wednesday, September 8th, 2021 AT 11:35 AM

4 Replies

Tiny
ASEMASTER6371
  • EXPERT
Good morning,

I would start by using an OEM relay from the dealer. This is an electronic relay that carries a lot of currents. A lot of aftermarket relays cannot handle the load at all.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

I attached the diagram and the location of the relay for you. Make sure the frame is cleaned off very well so the ground is good.

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Please let us know if you have any other questions.

Roy

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Thursday, September 9th, 2021 AT 5:37 AM
Tiny
CARADIODOC
  • EXPERT
Hi guys. Please allow me to add a comment of value. I didn't reply earlier because the photo of the relay I looked up only showed one mounting bolt hole. In the drawing posted by ASEMASTER6371, they show the same electronic relay used way back to the mid '90s on Neons and minivans. If this is the style you have, there was a recall to replace the two mounting screws and the relay if it had shorted. Seems the screws would break, then the metal heat sink would lift away from the sheet metal "core support" around the radiator. We were to clean that area, install a new relay with the two new screws provided, and we were to add heat sink compound. If you aren't familiar with that, it's like a white or cream-colored sticky grease that goes between the physical contact point of the body sheet metal and the metal plate on the relay. It promotes heat transfer so the relay doesn't overheat.

This electronic relay works by switching current fully-on or fully-off at varying percentages to adjust fan speed. This isn't actually a relay at all. It is electronic circuitry that turns a beefy switching transistor on or off. The idea with any switching power supply such as this is when it's switched off there's 0 current so now power, (heat) dissipated. When it's switched on, there's a lot of current, but no voltage dropped across the relay, so again, no power dissipated. The relay should remain cool under all conditions. That's the ideal version of the story. If it were perfectly true, that heat sink wouldn't be needed.

On that subject, I know from painful experience that if that relay is hanging by the wires after the screws broke, it will get hot enough to burn your fingers, so watch out for that.

If you already had the heat sink grease in place but are having multiple relay failures, given either the age or mileage you listed, you might suspect tight bearings in one of the fan motors. With the ignition switch off, try spinning the fans by hand. Both must spin easily and take some time to coast to a stop. If one stops almost the instant you spin it and let go, that motor will draw higher-than-normal current and will lead to the relay overheating.
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Thursday, September 9th, 2021 AT 5:35 PM
Tiny
MARK PATTERSON
  • MEMBER
My fan relay only has one screw but there is a plastic piece that helps keep it in place. I think the heat sink compound is a good idea - I will try that along with the OEM fan relay. I figured that it must be either overheating or shorting out.
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Thursday, September 9th, 2021 AT 5:48 PM
Tiny
ASEMASTER6371
  • EXPERT
Sounds like a plan.

All good information.

Roy
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Thursday, September 9th, 2021 AT 5:54 PM

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