Jump to content

Swapped a new sensor into my secondary fan rad sensor and fusible links started smoking


Recommended Posts

I've been having a ton of cooling problems in the Arizona heat, gauge gets close to 3/4 and I have to panic park and wait . So I figured replacing the secondary fan sensor that was broken (it spun inside the housing) would maybe help alleviate some heat. I ordered a 180 degree thermo-sensor because the goal was to get both of the fans to come on to try and cool it down a little. While I was checking the secondary fan by simply grounding out the connector I noticed something weird. The AC fan turns on (fan in front of the ac core) but the secondary fan itself does not. I thought it was weird but I decided to test it all anyway just to see. After getting the car up to temperature and having the primary fan kick on, the secondary never did work which is weird because the switch should be the same temperature. However, my fusible links started smoking and I immediately cut the ignition and waited a bit. I tried again without the AC fan plugged in and no smoke, but the secondary fan never did kick in after letting it warmup again and having the primary kick in. Is there any place that the AC fan relay and the secondary fan relay are connected? And why would the AC fan draw enough amperage by itself to start overheating the links? My links are old, but I've never had them overheat or smoke before. Any tips and help is appreciated thank you :)

notes on my current cooling situation:

  • cxracing starion radiator (fan grounds are securely bolted into the rad)
  • stock 3 electric fans
  • undertray is currently off and has been because it's easier to work under there
Link to comment
Share on other sites

Could be a couple things causing the links to smoke.

 

Likely you need to clean up your grounds. 

Alternately, fan motors may need to be refreshed (can bring to a DC motor or alternator repair shop).

Link to comment
Share on other sites

I have gone over almost all of the grounds in the engine bay and cleaned them a while back but I can try cleaning them again. Do you or anyone else know why the AC fan might kick on when the secondary fan has power? I remember reading something a while back that said something along the lines of them having a fail safe in case the engine  was way too hot but I can't find the post nor the wiring diagram for the fans in the FSM

Link to comment
Share on other sites

update, tested the secondary fan as per the FSM suggests and it's dead. Makes me grateful that it didn't work if only the AC fan almost burned down the car. For anyone else searching for similar answers on why the secondary and AC fan kick on together, their relays are wired together so if one kicks on the other will too.

Link to comment
Share on other sites

The fact that the secondary is dead could be the reason for your issue. 

 

The coils in the motor could be shorted, causing the fan to be dead, but also causing high amperage draw.

Link to comment
Share on other sites

Dang that's a good place to start looking thank you. If I measure the resistance between the two terminals would I be looking for super low resistance from a potential short? Since oem replacement motors are around $250 right now would I have a chance at rebuilding it?

Edited by The_Ginger_Stig
Link to comment
Share on other sites

My car setup is with the 2 low temp thermosensors installed with a jumper wire connected to each for added security that they both come on at the same time. I've never ran hot in the Texas heat since.

  • Like 1
Link to comment
Share on other sites

Good to know. My car never overheated when it was in Washington state but as soon as the Arizona weather hit it's been a constant struggle. Even with that giant aluminum radiator CXRacing makes it still gets hot sitting in traffic. The car only has around 45k miles so I hope it's not losing its head or head gasket, but I've started to doubt anything on these old cars will last another 3 years haha.

Link to comment
Share on other sites

Secondary fan and the AC fan are wired in parallel. Take a look at page 90 HERE

I would grab a meter and check resistance through that secondary fan. If it was a dead short or close to it. That would cause the issue. You can pull the secondary fan relay out and let it warm up again. Should see the AC fan come on close to when the primary comes on. 

Edit: posted before I saw your response. Sounds like you found the issue though!

Edited by psu_Crash
Link to comment
Share on other sites

@psu_CrashStill haven't found the issue :(, just responding to TexasQuest. I'll check the secondary fan as soon as I can. If I'm reading the wiring diagram on page 90 right, it looks like pulling out the secondary fan relay would bypass any power going to the secondary rad fan until the pressure switch, dual pressure switch, or the engine coolant temperature switch closes right? So if I pull the secondary rad fan relay out and the AC fan comes on immediately when the ign swt is turned on it suggests that 1 or more of the 3 previously mentioned sensors might be faulty?    However, if I pull out the secondary rad fan relay out and the AC fan doesn't immediately turn on and instead it turns on around the time that the Primary fan turns on, it suggests that there might be a fault in the secondary rad fan relay correct?

I'll be checking the resistance of the fan and will update within the hour.

 

I'm terribly sorry if that was too many questions or worded too poorly, I'm battling against time in college right now and I didn't get much time to read through the diagram.

I'll drag this car kicking and screaming to a daily driver status but it might take awhile :)

Link to comment
Share on other sites

17 hours ago, The_Ginger_Stig said:

@psu_CrashStill haven't found the issue :(, just responding to TexasQuest. I'll check the secondary fan as soon as I can. If I'm reading the wiring diagram on page 90 right, it looks like pulling out the secondary fan relay would bypass any power going to the secondary rad fan until the pressure switch, dual pressure switch, or the engine coolant temperature switch closes right? So if I pull the secondary rad fan relay out and the AC fan comes on immediately when the ign swt is turned on it suggests that 1 or more of the 3 previously mentioned sensors might be faulty?    However, if I pull out the secondary rad fan relay out and the AC fan doesn't immediately turn on and instead it turns on around the time that the Primary fan turns on, it suggests that there might be a fault in the secondary rad fan relay correct?

I'll be checking the resistance of the fan and will update within the hour.

 

I'm terribly sorry if that was too many questions or worded too poorly, I'm battling against time in college right now and I didn't get much time to read through the diagram.

I'll drag this car kicking and screaming to a daily driver status but it might take awhile :)

Not too many questions at all. We will get you there :)

If you pull out the relay that will take the fan out of the equation, but the AC fan will still run. 

With the relay out your AC fan should come on normally with either thermosensor 2, dual pressure or the pressure switch. Engine coolant switch isn't tied to the AC fan. You could jump ground to each of those, or any of those for testing purposes without having to let the car run. 

If that all works as it should with the relay pulled, then yes, you have an issue with either the fan 2 relay or the fan itself. I would put my bets on the fan motor or potentially wiring going to it. 

Edited by psu_Crash
Link to comment
Share on other sites

Oh boy. So I pulled out the 2nd rad fan relay (the relay on the right from the group of two relays with rubber shielding behind the horn)  as indicated by the FSM here, and none of my fans ever turned on. I got a used but good fusible links box for the head, tails, eci, etc and have all new links in it. The links didn't smoke or even get too hot so that solves the original problem I guess, but now I don't know why the primary fan and AC fan won't turn on. I did discover a massive new exhaust leak though :(. Did I end up pulling out the wrong relay?

I currently have the AC fan plugged in but I had the 2nd rad fan unplugged to avoid running power through it because if it's shorted then it'll probably just burn up the new links right? Looking at the wiring diagram on pg 90 of the FSM it looks like the only way that the "Radiator fan air condition relay (1)" can get power is through the 2nd fan motors connector but some of the other relays should have closed right? To restate: Primary fan and AC fan never came on even after the car was fully warmed up and a bit past half way on the coolant temp on the dash. My primary has never failed to come on at exactly halfway on that gauge so I'm completely stumped.

 

edit: I retried getting the fans to work at all with the secondary fan plugged in this time and without the secondary fan relay and still no dice. Fuse links didn't get too hot with the secondary fan plugged in though.

 

Side note for anyone that needs some NLA fusible links, I actually found some wire on the jungle site.

The oem Mitsubishi quick connect terminals are a little bigger than standard sizes so I just ordered a

pack of standard size terminals and opened them up and adjusted them.

This wire can be used for "green"  fusible links, .5mm^2

This wire can be used for "red" fusible links, .85 mm^2

Edited by The_Ginger_Stig
Link to comment
Share on other sites

 Share

×
×
  • Create New...