tried everything for cooling fan problem!

[drspode]

'92 Camry 4-cyl. with 160k miles. cooling fan doesn't come on even when dash temp gauge approaches red line. Done the following:
-replaced thermostat and water temperature switch
-checked fan relay #1 and engine main relay(ohms test and energized)
-checked wiring to water temperature switch
-confirmed fan motor works
-confirmed no bad fuses

desperate for new ideas. Anybody?

[sam333]

The circuit for the fans is fairly complex. Do you have a manual that gives step by step instructions for checking it? Do you have a schematic? Once you have eliminated the simple stuff, it comes down to going through the circuit step by step to find the problem. The factory service manuals( electric ) are best if you can get one. Sorry, I don't have time to search out the manual and go through the schematic.

[carsrus]

Do you get power to the fans when they are supposed to kick on?

[Pauloil]

Time to check grounds and the continuity of other wires. Look very carefully at the wires in back of connectors

[Stillrunning]

I'd also check power to relays with volt meter. After that it's bad/loose connection, broken wire.

[drspode]

I have the toyota shop manual with all schematics and have done the recommended diagnostics for cooling fan operation
--ignition switch on, fan stops(yes)
--disconnect water temp switch connector, fan rotates(yes)
--start engine and raise water temp above 199, fan comes on(NO!!) my problem

Also have tested temp switch in pot of boiling water with volt meter as well as all relevant relays.

I suspect that a thorough inspection of each element in the wiring schematic will help as has been suggested. Thank you all for your intelligent input. It's greatly appreciated!

[JohnGD]

The instrument gauge gets its reading from a one-connector sender on the engine, the cooling fan turns on/off from a switch at the bottom of the radiator.

Disconnect the connector at the fan switch (at the bottom of the radiator). Does the fan come on?

Because of the location of the switch and fan blades, be careful. You may or may not need the ignition in the ON position.

[sam333]

Is your gauge accurate? Do you have an IR type temp gun( to test the actual coolant temp)? Does the radiator fan come on when the AC is turned on?

[coffee-3000]

I'm thinking the same as sam333. Maybe your coolant is reaching 180 degrees ( or 200 degrees . . . I forget). I think the fan won't kick on until this happens.
I also saw a post on this forum where a guy had the same issue.
He openned his radiator cap and saw bubbles. He said he had air in the coolant system. He did some sort of procedure where he bleed the air out and then the cooling fan kicked on. Just a thought.

[drspode]

As far as the a/c fan coming on, I only know that I've tested the motor and it works. I've also replaced the thermostat with the appropriate one so that should allow for the radiator to come up to temp(however the theory that air could be in the system would possibly inhibit that. I thought that I'd bled all the air out but will check again. If this solves the problem, props to coffee-3000) I've let the car sit at idle for long enough for it to easily reach temp for the fan to kick on(borne out by the dash temp gauge as well as time) but no dice. One thing is different from stock that might be the cause. Put in aftermarket radiator and temp switch and drain hole are now the same(separate on stock radiator). I can't imagine that could be the problem though.
Anyway, once again thanks to all of you who've given me your time and input.

[NapalmFTW]

If you disconnect the temp sensor (its on the drain plug) the fans should kick in no matter what temperature the coolant is at.

IF that's not working then you have an issue elsewhere, however I believe you said you'd tried that already.

[sam333]

When you turn on the AC, both fans ( cooling and ac fans) should come on... do they? Are you saying you moved the position of the temp switch? if so ,then yes that could make a difference . What I was asking above, is why do you think you are overheating? Does the temp climb higher than normal when driving? It is not unusual for the temp gauge to climb higher than normal with prolonged idle. How do you know your temp gauge is accurate? Do you have an aftermarket temp gauge?