Having the time of my life with this radiator fan not coming on

[Donnyten]

Im using a wiring diagram fyi. One of the more frustrating issues ive had to deal with. Sub cooling fan switch on thermo housing didnt work, so i replaced it since it didnt bridge Continuity at the right temp.( condenser fan still came on after engine off , no clue how if i put the thing in scolding boiling water and no continuity since the module underneath seat uses the ground as an input) Jumpered fan switch connector at bottom of radiator key on both cooling fans come on. All fuses and relays work. Thermo switch on radiator works. I do have a newer after market (import direct) switch as wrll, works. Just for the heck of it checked continuity from blue wire on connector to blue wire On radiator fan timing module underneath seat. Can power fans at thermoswitch connector on radiator, at the relay, and by jumpering the blue wire at back of module straight to ground and the fans come on. This tells me wiring integrity is good. Checked for power at the 3 inputs, two which need key on, one hot all time to module, all good. It seems like the module isnt telling the fans to turn on or it isnt getting a grounded input through the blue wire from the thermoswitchon radiator. Radiator flow is ok. The top hose gets hotter quicker than bottom one but when the bottom hose gets hot the fans do not fucking come on. I read that thermostat needed to be oriented with hole up, did that, even replaced thermostat for the hell of it with a different brand. WHAT THE HELL IS GOING ON HERE? Im going to try to take some input and output measurements from module... if no ideas im going to just bypass that damn module and go straight to the relay. Of course when the car is turned off the condenser fan come on... temp gauge is at 3/4ths full before i have to turn the car off. NO FANS. Coolant in hoses damn near steaming out of upper hose so no, i dont think i need a thermometer to see how hot the engine is. Again.. BOTTOM HOSE GETS HOT! So i know the flow is good

Need another corona

[1989accordaz]

I had a similar problem, I replaced the radiator and it solved my issue. It was hard to teoubleahoot because everything around it tested ok.

[Donnyten]

What led to you replacing your radiator? Was it clogged up?

[Donnyten]

Going to isolate the radiator issue by taking the thermoswitch out and putting it in high temp water in a pot, if the fans come on, im replacing the radiator, if not, i'm deleting this fan control module.

[1989accordaz]

I was clogged up, my thermoswitch worked when testing it on hot water. Also, looking down inside the radiator, with the cap off, I could see some of the passages clogged.

[Donnyten]

Update. Out of curiosity took the fan switch from the radiator and put it in a pot of boiling water with the car and run.i used the old switch this time. To my surprise the fans run but didnt before even with the old switch. So now it seems to be A Radiator flow issue or switch which was tested and brand new. Going to test with the new switch and report back.

[Donnyten]

Both switches in boiling/ hot water will turn the fans on.this is with the connector hooked to switch. Pulled radiator and ran a hose through it.. perfect flow, no sludge build up whatsoever.. *scratches head*

[2ndGenGuy]

Curious... I have been having this problem with our race car... an 89 LXi. Everything tests out fine, even put in a new fan switch. Fan kicks on if I short the two wires at the fan switch, so I would assume everything else is working fine. Being that this is a race car, I'm inclined to just bypass and install a switch on the dash. Didn't have any overheating issues at the track, but I would feel better in case there is a red flag or something and we have to stop and idle on the track...

[Donnyten]

Beats me. the entire fan circuit seems to be intact. No idea what could be wrong. shit is weird.

Only conclusion i have in my case is for whatever weirdo reason the switch isnt being fully submersed in the coolant when its in the radiator.

3 things come to mind, new radiator ( money), Hose adapter in between bottom hose- switch, or better and more experimental, relocate the main fan switch from the radiator to where the auxiliary ( a/c fan) switch goes on thermostat housing. If the fans STILL don't come on, i'm bypassing the entire timer module circuit and installing a switch.

[Donnyten]

People musta gotten rid of their 3geez lol. Forum is dead.

Anyway.. i relocated the radiator switch to the thermostat housing and ran two long wires. Problem solved. Fans come on when they should and at the right temp

[2ndGenGuy]

Nice Fix! So weird that it won't work in the radiator. I might try getting a new radiator for the race car and see if that works... Or just relocate the sensor too... LOL.

Forum chatter is pretty slim these days. Most of it is on Facebook. Most forums are like this nowadays.

All the good archived info is still here though.

[1989accordaz]

Glad you got it fixed! I would have spent the 65 dla for a new rad. Not as creative as you, well done and thanks for posting a follow up.

[Donnyten]

Getting a new radiator would have been the fix if i were an actual mechanic with a shop, but, its nice to know there are other ways around things. The only thing I lose Is the A/ C fan functionality for when the cars off above temp but i can't see my car getting that hot anymore, it doesn't even hit middle anymore now that the fans come on. of course I could maybe tie into the timer module circuit somehow. On a side note, I never knew a facebook group existed. Gotta link or name of the group?

Now, onto the next issue. low fuel pressure diagnosis..

[InAccordance]

Working on a similar deal with the gauge sending unit. It was on the back of the old intake but that's gone. Stuck it on top of the thermostat housing where one of the old vacuum thermo switches was but still isn't working. Only thing I can figure is what you were talking about, not getting submerged in coolant. Is a bit disconcerting with no temp gauge but my fans are kicking on when they should if I leave it idling for a while so it's not getting too hot.
Thought about making a fitting of sorts to go in line with the bypass hose I made cause that hose gets warm so I know there is good flow there.
Not trying to jack your thread:D

[Donnyten]

Youre free to hijack away! as long as my fans come on! lol the thread is yours now. also do you have a pic of the switch youre using?

[Oldblueaccord]

Nice Fix! So weird that it won't work in the radiator. I might try getting a new radiator for the race car and see if that works... Or just relocate the sensor too... LOL.

Forum chatter is pretty slim these days. Most of it is on Facebook. Most forums are like this nowadays.

All the good archived info is still here though.


wild guess only is the switch is not grounded thru the radiator for some reason or an after market radiator is not constructed correctly.

[2ndGenGuy]

Hmm... interesting thought! I'll try adding a ground to it and see what happens.

[InAccordance]

Youre free to hijack away! as long as my fans come on! lol the thread is yours now. also do you have a pic of the switch youre using?

I'll get one at some point but it's just the one from the back of the carb intake.

[gp02a0083]

wild guess only is the switch is not grounded thru the radiator for some reason or an after market radiator is not constructed correctly.

I dont think this is an out there idea. I replaced my factory oem radiator with a new aftermarket denso. I recall the ends being different in addition to having a smaller cap diameter. So possibly?.

I am also wondering if the original harness had any breaks in it or something? Did you ever do a resistance/contunity check the whole harness or just pinpoint? Another issue ive come into is the module box typically frying a diode for some reason across 6-7 ones ive ripped apart

[Donnyten]

How and why would the switch get its ground through the radiator? It gets its ground via the black wire when the switch closes and bridges its connection to the blue wire thru the timer module which signals the fans to come on. I put the switch in boiling water which in no way was connected to the cars frame unless im entirely misunderstanding something. Radiator is factory

Did continuity and resistance checks through out the entire circuit. Everything checked out.

[Oldblueaccord]

how does continuity work? what does a meter do to "check" continuity ?

like I said its a wild guess.