My 90 civic will start to run hot when I'm sitting and idling for a long time( drive through, heavy stop and go traffic). I can turn the heater on and that helps, but the gauge will go down when I start moving freely again. I'm thinking the cooling fan isn't working. Have checked while it's done this and it isn't on. I've changed the relay out to no avail. I'm very mechanical but electrically dumb. Is it possible it's just the fan or there isn't power. I honestly don't know how to check the power to it

 

Give the fan power yourself, disconnect the fan connector, run a wire straight from the battery +/- to the fans connector, if it doesnt turn on, you need a new fan.

 

You can also just jump the fan switch. I'm not sure if that is more difficult or not. But supplying power to the fan will test if it is a wiring/relay/fuse issue or the fan is bad.

 

Ok so here is where my electricity stupidity comes into play. A wire each from ps and from neg to the connector? Does it matter on which side of the connecter? And what type of wire? followed by car running or ignition just turn on

 

It doesn't matter which way you test it.
The fan will spin in reverse if you get it mixed up.

Wire should be around the same thickness as the wires going to the stock connector.
A little bigger or smaller isn't going to hurt for this quick test.

Ignition can be off.
You don't need the ignition on to get the battery to start working

 

Duh I guess I knew the ignition didn't need to be on to test off the battery, and I should have proper wire, just so I'm clear wire off pos and a wire off neg to test? I will do it when I get back home

 

Ok I checked the left fan by using wire directly into to the battery it did turn on, I cannot get to the connector on the right fan with ease will have to do it from underneath. Could the left fan not turn on because the right one won't or could it be another issue?

 

As far as I know, one fan is temperature controlled and the other only becomes operational when the A/C is turned on.

 

Ok finally got to where I could check the second fan. Both fans turn on when touched to the battery. any ideas?

 

Key on, unplug fan switch and see if the fan will turn on by jumping it. If it does, then your circuit is good. Continue by pulling the fan switch, test for continuity as is and again after placing the sensor side in boiling water. Should have an "open" condition until it reaches a specific temperature close to boiling.

If it doesn't turn on by jumping the fan switch connector, you'll need to use a multimeter to start tracing and looking for an open. I'd first test to see if you even get voltage going to the connector at all.

 

Ok forgive me, but remember I'm electrically stupid. What is the fan switch? And where will it be located on this? Jump it the same way I jumped the fans? Just power to the battery? Then finally where is the sensor located so I can pull it?

i have a multimeter but to test the voltage going to the connecter which side is which or will it matter?

 

the real fan switch on the back of the block is a two pronged sensor.

not a d series, but you get the idea.


there is a rubber boot around the connectors that will likely crumble apart when you take it off, dont worry its not a big deal. take the two connectors off, then stick a wire between the two connectors (the wires, not the two prongs of the sensor). the fan should turn on, with the ignition on.

if it doesnt, then something in the fan wiring is bad (fan or relay, or a break in the wiring).

if the fan does turn on, which usually it does, and youre CERTAIN the fan NEVER turns on when operating normally, then the switch in the engine is bad. but im 98% certain its probably fine.

so if that isnt it, then you need to start replacing things like your radiator cap, thermostat (which i think you said you did) and even your water pump which could be weeping and raising the temperature as the pressure drops.

if your water pump has never been replaced, then likely your timing belt hasnt either. which is an important thing to do.

dont let your car overheat, or else then youll be looking at a blown head gasket and now youll need to do much more major engine work.

if you notice it overheating, turn your heater on full blast hot. it will help cool the engine.

 

^^ in addition to all that, if you have already allowed the engine to overheat, then it is recommended that you change out the thermostat when you get everything sorted out. Thermostats are actually somewhat fragile inside and overheating can easily damage them.

 

Ok forgive me for the long delay. Had issues with my Odyssey that took priority. Where is that located in the picture? Is it on top or bottom of the car?

 

Not to jump into the convo, but it's located underneath your intake manifold. Top of the block, just above to the right of your alternator.