Desperate Help Needed on 1986 Honda Accord LX

[Difranco]

My cooling fan will not turn on.

I have jumped/bypassed the Thermoswitch on the passenger bottom of the Radiator, and the fan will turn on and runs fine.

This proves the following is good:

Relays
Fuses
Fan motor


However when I replaced the Thermosensor, the fan did not come on as it should. So I tried a second one thinking I got a bad one the first time around.

Still nothing. The does not turn on by itself, even after the temp gauge gets to about 3/4 of the way.

I have tried the Honda Shop Manual info I've exhausted that information. The hoses going to and from the raditor do get hot so I am confident the thermostat works. I've done the bleeder valve / refilling routing as well just to be sure the system doesnt have air pockets etc.

Suggestions, tips, etc are needed.

Thanks in advance.

[stat1K]

this should not be in the 2g section it should be in the 3g tech section...

but as for help goes you could always just wire the fan to a switch like i have done and or wire it to a 12v + ignition so it runs always... taking the thermoswitch entirely out of the question. that's my 2 cents.

[BITESIZE]

So uhhh yahhh did you check your fuse? Might be a short somewhere.

[2ndGenGuy]

Damn I got all excited thinking there was some new 2gee action.... Guess not :(

[Difranco]

All related fuses tested good with multimeter. Also fan wouldnt turn when thermoswitch bypassed, because the circuit would be interrupted by a blown fuse or bad relay.

Sorry about the mis-post in the wrong section, new to honda's, I thought I read this vintage was 2G.

[BITESIZE]

Check both temperature sensors.

[Difranco]

You mean the TW sensor near the top of the engine? The one with the two rubber tubes running out of it? OE service manual doesnt show it related to the fan motor function.

How does this affect the fan?

This isn't meant to be smarta$$, but rather I like to understand things and have the light go on in my head.

[BITESIZE]

Check the one at the bottom of the radiator, and the one buy the thermostat. If the sensors are bad, your fan will not turn on. They tell your fan to turn on when they heat up to like 180 degrees...

[Tailfin]

I'm having a similar problem, and I found there is another thermoswitch mounted on the back of the intake manifold towards the passenger side. The wire going to the crimp for the connector to it was broken, and I haven't gotten to fixing it back up yet, but that switch might also be important. I'm hoping so :-P.

[88Accord-DX]

My guess is there is a wire broken between the temp. sensor & relay. You only have blown fuses when shorted to ground.

[Blkblurr]

Could be a badly clogged radiator. This might cause the temp switch to not see the true heat in the radiator. IF you bypass the temp switch at the connector on the temp switch and the fan runs it means the temp switch is not tripping which in turm means you have a bad switch, a clogged radiator or the wrong switch for your car. I don't think it could be anything else.

[A18A]

mine had the same problem, i swapped the thermoswitch or w/e its called at the bottem of the radiator, and it worked :) maybe u just had bad luck on them? you could wire it up and get a real boiling hot cup of water and put it in and see if your fans turn on. i think it has to be above 200 and something degreese before it turns on, i forget. anyways good luck ;)

[Tailfin]

I'm a tad confused here... Which switch(es) send the signal to the temperature gauge on the dash? My manual seems to indicate it's the one on the intake manifold (on the carbed car). In any case, does a working temperature gauge eliminate anything, or is that unrelated to what the fans use to turn on?

The reason I ask is because I just replaced that manifold temp switch thingy, and put a new connector on it, and the fan still won't work. I just had the intake manifold off, and lost some coolant while doing that, enough so that I don't feel heat now with the car warmed up. I figured that solution was easy, and the coolant wasn't hitting the temp switch, but the one on the radiator is at the bottom, so it must be getting some...and when I hit the pedal, the temp suddenly went up to normal-ish, which I took as I'm low on coolant, but the water pump pushed some onto the sensor... However, then the gauge showed it beginning to overheat without any further pedal. Basically, I'm wondering it despite the aforementioned, the reason could be low coolant. I'm putting it in anyway, of course :-P...but for theory's sake...

[Tailfin]

Update for those interested... The coolant did not fix my problem...figures, but I highly suspect the AC diode, since the continuity tested, but very very weak. It also looked quite corroded. Only problem is, I don't know anyplace that actually has the stupid part... The harness for it looks equally bad. Anyone know the site to get Honda parts direct?

[lostforawhile]

if you turn the key to ignition and bypass the switch at the lower corner of the radiator,the one with two leads,the fan should come on. if it does you have just bypassed all your other problems. that switch is a simple two wire deal. certain temp it closes and the fan comes on. if you have already done this and the fan runs,the switch is bad,or you have other problems,clogged radiator,water pump going out etc. possibly a bad thermostat too. the small temp sensor on the back of the intake manifold,the one with the single wire,thats for your temp gauge. it has nothing to do with the fan itself. the fan sensor is the big sensor in the lower corner of the radiator. also check to see if the connections where it plugs into the switch aren't corroded. if they are corroded and aren't making good contact the fan won't come on eithier.