Hey guys, im new to the forums and I am having troubles with my 97 honda civic, okay so my car has an ls-vtec swap in it and it runs and drives fine the only things wrong with it is that first off my radiator fan never comes on, i dont have any ac nor power steering in the car and i have a half sized radiator, i ran some jumper wires from the plug of the fan to the battery and the fan comes on but without it, it doesn't and as well i checked all of my fuse's and they are all good i also replaced my radiator fan switch and that didn't change anything as well, i bought a new oem thermostat for it but i haven't replaced it to see if that could fix the problem but i talked to the guy that i got the car from and he said that he just replaced the thermostat right before i got the car. My car never over heats even with the fan never coming on, but when the temperature outside is like 70F degrees and above my car will idle really funny and die when i come to stop sign or when i pop it into neutral to switch gears, it has no problem starting right back up once it dies though, and my temperature gauge when it's that hot out will be at middle temp. so its reading normal operating temperatures but when it's like that, when my car reaches normal operating temperatures that's when it starts to act all funny, and like i said it only happens when the temperature is hot outside or like after 40-60 min of driving, but when the temperature is below 70 outside my car stays really cool it barley reads above the cold mark and my car runs like a champ without any issue at all while im driving it, but if i stay without moving for a period of time my temp. will start to rise to the mid point and not move from there but the idle issue will start to happen again until i start moving and the air from driving it cools it down as it hits the radiator, and again my fan never kicks on or anything when any of this is happening, and for some more insight my car has a p72 ecu and it is throwing a check engine light but it's for an 02 sensor that i am sure is from my cat or rather my test pipe, i know that this is a very long posting but i wanted to be as clear as possible if anyone could please give me some help and any input is highly appreciated thank you to all in advance for any help that i may receive i hope to hear from you guys asap thank you :D

 

Jeezzzz that was a long sentence.

Hard to believe engine is not overheating if your only running a 1/2 rad with a rad fan that is not working, possible I guess.

Rad fan is not needed if car is moving, [airflow through rad], but at a stop and idling or stop and go traffic, overheating would occur, more so on hotter days.

I would use a thermo gun to see exactly what the engine temp. is whgen stalling is happening.

You will need to check the whole rad fan circuit.

The rad fan has a constant ground, [black lead], unplug the fan and test the black lead in plug for continuity to ground.

Power for the rad fan is supplied by the Rad Fan Relay, [RFR] located in the engine bay fuse box, fuse is fuse 57 - 20A, [hot at all times] in engine bay fuse box, relays coil fuse is fuse 17 - 7.5A, [hot in run] in under dash fuse box.

Make sure fuse 57 has power on both test tips at all times, make sure fuse 17 has power on both tes tips when ign. switch is in run position.

If fuses are good, pull the RFR and test for power, one terminal should be hot at all times, [#30 or #87], if so, use a paper clip to jump #30 and #87, rad fan should turn on, if so wiring is good.
Turn ign. switch to run, a second terminal in RFR plug should now be hot, {#85 or 86], if so, control wiring is good.
Unplug the Engine Coolant Temperature Switch, [ECT switch] test the black lead for continuity to ground, if good, use paper clip to jump the leads in the plug, [black and green], now test the terminal in RFR plug, [#85 or #86] that did not have power when ign. switch was on, for continuity to ground, if good, replace the RFR, it's bad. 94