Running hot

[captndave737]

Ever since I put in my aluminum radiator and dual fans my temps have NEVER been higher than 5 deg. above my Tstat opening temp. which is 180. My chip commands the fans at 180 also. no matter how hot it was outside. Didn't matter if it was in stop and go driving or on the highway.

About 3 weeks ago I noticed my temps were about 10 deg higher than normal in traffic and would go down on the highway. When I got home I checked and saw my fans were running.

A few days ago I nearly overheated! Temps got up to 215 in traffic. When I got home I looked and the fans were not working. I have my fans hot wired with 2 relays. Each relay operates one winding on each fan and it's set up so both are always energized whenever the ECM or AC sends a low speed signal so they only operate on high. I figured the low speed relay was bad so I threw a spare in. Fans still didn't run. I checked the output of that relay and it was sending 12v to the windings of the hot wired fan relays. Pulled the hot wired relays and checked them. BOTH had failed. Jumped the terminals and the fans ran fine, both windings were good.

The bottom line is obviously one failed a few weeks ago so the fans were operating on low thus the slightly higher than normal temps and the second failed a couple of days ago! Here's my setup.

 

[michael evans]

You have two fans right ? By reading your diagram, it looks that you have four.

Your diagram does not show how the relays are controlled.

The ECU engierizes the "low" at 180 degrees (as your chip is programed to) and high when you have the AC is on . That is how the system should work.

Not sure the brand name of your relays but it sounds like the contacts are to light for the fans.

Are the rated for 40 amps ?

 

[Pronto]

Both hitting at once could be too much for the relays. I believe Caspers has a small delay for the second fan.

 

[earlbrown]

What brand relays were they? And were the small square kind that are only rated for 30 or 40 amps?

 

[captndave737]

You have two fans right ? By reading your diagram, it looks that you have four.

Your diagram does not show how the relays are controlled.

The ECU engierizes the "low" at 180 degrees (as your chip is programed to) and high when you have the AC is on . That is how the system should work.

Not sure the brand name of your relays but it sounds like the contacts are to light for the fans.

Are the rated for 40 amps ?

There are 2 fans. Each fan has 2 windings. If the wiring was original one winding on each fan would be energized on low and the others on high. One relay handles one set of windings and the other relay the other. The stock fan works the same way. The setup is either a Caspers or Racetronics hot wire kit, think it's racetronics. I just rewired it so when the fans come on they are on high. (Both relays energized) and i removed all stock unused wiring when I re did the wiring harness.

 

[captndave737]

Both hitting at once could be too much for the relays. I believe Caspers has a small delay for the second fan.

Doesn't really matter since each relay only carries half the load.

 

[captndave737]

What brand relays were they? And were the small square kind that are only rated for 30 or 40 amps?

Nice looking sealed relays that came with the hot wire kit. I opened therm and was amazed at how tiny the internal components were. I can see why they burned out. I ordered some new heavy duty relays from Caspers.

I'm not really complaining about what happened since I've had these for well over 100,000 miles just pointing out the symptoms in case it happens to someone else. Cheap, Autozone Ram Chargers fans just keep on going.

 

[Pronto]

The Racetronix comes with fuses in the line.

 

[captndave737]

My diagram shows a fuse between the battery and the relays. I went back through my receipts. It was purchased with fans from Gbody parts. The fans died pretty quickly and i replaced them with parts house Ram chargers fans.

 

[michael evans]

There are 2 fans. Each fan has 2 windings. If the wiring was original one winding on each fan would be energized on low and the others on high. One relay handles one set of windings and the other relay the other. The stock fan works the same way. The setup is either a Caspers or Racetronics hot wire kit, think it's racetronics. I just rewired it so when the fans come on they are on high. (Both relays energized) and i removed all stock unused wiring when I re did the wiring harness.

Now it make more sense what you have.

The drawing you have tells a different story.

So each fan has two relays ? Or fans have one relay that controls the low and one for the high.

Sounds like you are drawing more amperage than what is needed.

How are you controlling the relays ?

What brand are the fans ?

 

[michael evans]

.

 

[captndave737]

The drawing is a standard schematic. Each set of windings has one relay so 2 relays send power to the fans.

The relays windings are activated/ controlled by the stock low speed relay which is controlled by the ECU and whatever the chip is burned to. I had mine burned to come on at 180 deg.

Relay windings draw very little current they just close a switch.

The contacts draw all the current and the fans themselves determine what that is and it's fused so if the current is too high the fuse would blow.

I think the relays were just low quality.

Fans are from Advance Auto. Doge Ram chargers cheapos with a lifetime warranty.