Overheating problem on 2003 WRX. Possibly fan relay failure

[rossbrunson4]

I noticed when sitting in holiday traffic my temp gauge jumped to nearly pegged. The fans are not kicking on... I checked both 20 A fuses and they are intact. When I turn on the AC both fans start running so they are working. I think it may be one of the many relays running the fans. I do not fully know how each relay work so any info on which may be messed up would be awesome! i plan to buy all new relays tomorrow if I dont get any info so I hope that works haha. Please any advice could save me on my holiday road trip. Gotta be back to school by Sat so i got to get this tracked down.

Thanks,

Ross

[SD_GR]

I would expect fan relay failure to generate a CEL though.

[T0rque]

typically fans, sensors or anything cooling wise wont typically set a cel

[rossbrunson4]

CEL? check engine light? no lights on. I feel it might be the water sensor temperature. fans are working till it over heats then they shut off. does anyone know what the difference between a main fan 1/2 and sub fan 1 or 2 means. relays work for the sub fans but the main fans seem to have no effect on anything.

[rossbrunson4]

I think its the engine temp sensor btw. if anybody wants to figure out a similar problem check that. its behind the altornator. Kinda lame but check it out and un hook it. this should make the fans run full time and you wont over heat. thats the test. just spend the 15$ and fix it. it goes out normally i guess

[Dange-Russ]

This side of the world at our shop we have endless customers coming in for thermostat seizing up.

We fit Mishimoto 68' thermostats. Stock are terrible. Dunno if the fans thing could be related to that but next time your car is hot carefully feel the pipe on the top of the radiator and then pipe at the bottom of it and see if both are at a similar temperature. If ones hot and ones cold then the thermostat has given up the ghost.

[rossbrunson4]

@ Dange-Russ. I have a new Grimspeed 160 degree thermostat as well. which i wont put past failing. the only thing that i feel proves its not the thermo is that it cools down with prober air flow... correct me if i am wrong but if the thermostat is not working no water will flow period... aka no cooling at all. plus its a fail open thermostat. I would assume you know more than me but this is just based on other input i have gotten. I will look at the thermostat if needed

[Dange-Russ]

No you right. Very common problem with these motors is the stock thermostat but if you have flow then it's not the thermostat.

[rossbrunson4]

My next assumption is that it has to do with a certain over heat fan relay.... thats a guess btw. I still have full clean oil and plenty of radiator fluid. is there anything else I can check?

[oguitar]

If the fans are working and you are overheating then you might have air in the system. Burp it and see if the problem goes away.

[SD_GR]

In our area the stock thermostat is generally better than the imitations in terms of reliability.

This doesn't mean they never fail of course.