radiator fans always on

[bronzemaxell]

my 97 camry 4cyl auto recently has the radiator fan always on when the key is at ON position, the AC is off, both radiator fan are on. i did a search and and came back with a few possible causes, Fan relay, ECT switch or sensor , is it true that when the ECT switch has open circuit, the fan is always on?

the MPG has been going down weekly, i am was getting 23 to 24 mpg average local and highway a few weeks ago, and last week i was getting average 19 mpg, same driving habbit. there was oil leak at oil pump, and at valve cover , i fix the oil leak, along with 4 new oem double tip spark plugs, new fuel filter, engine air filter, new cam seal, crank seal, oil pump seal, new timing belt, ps belt, ac belt

has anyone experience the similar problem?

[95PimpingCamry]

On the gen 3 the fans are controlled by a temp sensor mounted at the bottom of the rad. Sounds like you either have a bad relay or temp sensor. And yes if there is an open circuit in the temp sensor the fans will be on.

[nuchieboy]

i had the same problem...fan relay #2 was shot

[Mike Gerber]

Originally Posted by nuchieboy

i had the same problem...fan relay #2 was shot

Try locating and tapping that relay to see if the fans then turn off. If so, you will know you have isolated the problem to that relay and will be replacing the defective part.

As far as mileage, with the fans running all the time the car is taking a longer time than normal to reach operating temperature, if it ever does actually reach operating temperature. The colder the engine temperature, the richer the fuel mixture will be. A richer than normal fuel mixture will result in excess fuel consumption. This is also not good for your catalytic converter, since the engine can not efficiently burn all that fuel and some of it goes out the exhaust valves and through the exhaust system. Get this fixed as soon as you can.

Mike

[bronzemaxell]

here is the update

i spent a few hours reading the toyota service manual on the coolant section,

it saids if i unplug the ECT switch at the radiator, ignition key ON, fan rotates,

mine is, ECT switch plugged, fan always rotate, the service manual instruct me to look at the:

ECT switch and FAN relays,

i checked all 4 relays at the fuse box under the hood with a DVM, main relay, fan #1, fan #2, fan #3, all with in spec.

then i check the ECT switch, i unplug the ECT switch, check the continuity on the relay (the one go to vehicle harness) there is continuity

then i check the other side of the ECT plug, the one that goes to the ECT sensor under the radiator, i have no continuity, the service manual said

when coolant temp is below 181F, (low temp), there should be continuity, fan no rotate
when coolant temp is above 199F, (high temp) there should be continuity, fan should rotate

now, if i jump the connection on the ECT switch to the vehicle harness, faking there is a continuity at ECT switch, when i turn the key to ignition ON, fan doesn't rotate anymore, if i turn on AC, then the fan starts rotate.

i think i might have a malfunction ECT sensor for the radiator.

my question is, is it ok to find a ECT sensor from junkyard?

[95PimpingCamry]

You probably could, but it's best to get one new. You never can tell the condition of sensors in junkyards or how long they will last.

[bronzemaxell]

Originally Posted by 95PimpingCamry

You probably could, but it's best to get one new. You never can tell the condition of sensors in junkyards or how long they will last.

i read somewhere, people spent $90 for a new ECT sensor from dealer,
i have relative works at junkyard, i can get a used ECT sensor for free
that is the only reason i am asking.

[95PimpingCamry]

If you can get it for free and are willing to put forth the labor knowing that it might not work, go for it. Personally I would just get a new one for peace of mind, and I'm sure you could get one for less than $90 from an auto parts store, but they're still not cheap.

[Stillrunning]

I purchased my ECT at Auto Zone for about $28. Make sure it comes with a new o-ring.

[bronzemaxell]

Originally Posted by Stillrunning

I purchased my ECT at Auto Zone for about $28. Make sure it comes with a new o-ring.

i bit the bullet, just ordered a new ECT switch for the radiator from dealer, it is $65 after 25% discount, so i would imagine the retail is close to $90, it does come with the new o-ring. hopefully this solves my problem.