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Discussion Starter #1
I have a 7th gen Accord that has recently started to overheat at stoplights. I believe the issue is the radiator fan. When I run my a/c both the radiator fan and the condenser fan come on so I know they both work. However, when I turn off the a/c the radiator fan never comes on. I have an OBDII scanner and I can see that the Engine Coolant Temp gets up to as high as 232 degrees F. The fan should trigger at around 200 degrees. I know that there are 2 sensors for engine coolant in the 7th gen Accords, one at the bottom of the radiator (ECT2) and one in the back of the block (ECT1). My question is which one of these triggers the radiator fan? Or it is most likely a bad relay?
 

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sip_99
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The easiest and cheapest fix would be...change the relay in the fuse box.

Next, if that doesn't work, the sensor at the bottom of the radiator is the RADIATOR Fan Switch.

That sensor is easier to replace than the the one in the back of the block.

I replaced my radiator last year and I transferred my old fan switch over from the old rad to the new rad.

If you switch the fan switch on the bottom of the rad, be sure to torque it correctly (I believe the nut is the 1 CM diameter if I'm not mistaken. You'll probably need a longer socket though.

Ensure sure if you buy a new fan switch, that it comes with a new washer (that is really important). Or if you buy an OEM part, it should come with one from Honda.

And if I didn't answer your question yet...yes the radiator one controls the radiator fan.
 

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Before buying a relay, swap it with an identical relay. The AC compressor relay is the same. If the fan now works and AC doesn't, then you know it's the relay. Also, try tapping the fan motor with something heavy, it may be going bad. Better yet, get a meter or test light and ensure that you are getting 12V at the plug.
 

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Discussion Starter #4
I have swapped the relays with the back defroster and that didn't change anything so I don't think it is the relays. I think it is the sensor in the radiator that needs to be changed. Can anyone confirm that the temp showing on the dashboard reads from the internal engine sensor (ECT1) and not from the radiator sensor (ECT2)? That would make sense to me but just want to confirm.
 
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