Radiator fans

[drivel60]

Hello. My name is Edward (or drivel60). I have a '96 Camry LE 2.2. in noticed that the fans do not activate when the engine becomes hot. The temp guage almost reaches the red, even when the heat is turned on full blast.

I've replaced the bottom sensor, with no luck. When I unplug the bottom sensor, the fans activate but the temp gauge still travels to the red.

Any suggestions/thought/advice will be greatly appreciated.
Thanks
Ed

[carsrus]

Leave the fans running full time and see if it overheats. If it does the fans arent the issue. Theres one more senor that activates them but i dont remember it off the top of my head.

[Stillrunning]

Originally Posted by drivel60

the fans do not activate when the engine becomes hot.I've replaced the bottom sensor,When I unplug the bottom sensor, the fans activate but the temp gauge still travels to the red.

Change your thermostat.

[drivel60]

reply to stillrunning: did that happen to you? if so, did changing the thermostat solve the problem?

reply to carsrus: i don't quite like the idea of seeing if the car will over heat. when the gauge gets to the red, isn't that a bad thing? also, if i follow the bottom hose up to the motor, there appears to be 2 sensors, side-by-side, that are plugged into some type of water valve. i'm sorry, i don't know the names of those items. one is a one wire sensor and the other is a two wire sensor. unplugging either of them doesn't make the fan turn on.

[drivel60]

did that happen to you? if so, did changing the thermostat solve the problem?

[Stillrunning]

Originally Posted by drivel60

did that happen to you? if so, did changing the thermostat solve the problem?

Not sure if you're being sarcastic but it would have if my thermostat was not opening and flow to the rad, and hence the fan switch, was restricted thereby preventing the fans from activating. Changing the stat is a cheap way to trace the problem.

[drivel60]

no, i was not being sarcastic. i would never be sarcastic, especially if i were soliciting others for assistance. now if we were to become close friends and knew each other and "could roll like that" then hey, sarcasm would only aid in strengthening a friendly bond, eh?

and you're right, changing the thermostat is definitely a cheap way to trace the problem and i'm all about being cheap.....sort of. so i'll change the thermostat. i'm also leaning towards changing that green relay.

i greatly appreciate your input.

[TedL]

Originally Posted by drivel60

i'm also leaning towards changing that green relay.
.

Look around at your other relays for the same p/n to swap as a test.

[Stillrunning]

Originally Posted by drivel60

When I unplug the bottom sensor, the fans activate

Look around at your other relays for the same p/n to swap as a test.

His relays are fine. The only other switch that turns the fans on is the A/C. Assuming the new temp switch is not defective his problem is elsewhere.

[drivel60]

Originally Posted by Stillrunning

His relays are fine. The only other switch that turns the fans on is the A/C. Assuming the new temp switch is not defective his problem is elsewhere.

yeah, i looked at the other relays and saw some that have the same p/n. i thought about swapping them around but was unsure. now that you mentioned it i'll swap them around when i get home.

i also wondered if i bought a defective temp sensor.

thanks for your input. i'll keep plugging away at it.

[drivel60]

i replaced the thermostat today. i swapped around the relays that had the same part number. it didn't solve my problem. now, the check engine light came on. the codes are P0110 and P0115. great, is there anything else that can go wrong?

[JohnGD]

Check your wiring and connectors. Did you leave something unplugged after the work?

You have both temperature sensors acting up at the same time, so I don't think they're both going bad. It may be electrical related. Maybe use an ohmmeter to check the sensors. At operating temp they should read about 200 ohms.

Are both the upper and lower radiator hoses hot when the engine's overheating?

If the lower radiator hose is hot, does the fan come on by itself?

Also, if the fan doesn't come on and if you disconnect the fan switch connection (to make the fan come on), does the temperature begin to drop? (Be careful of moving fan blades!!)

[drivel60]

Originally Posted by JohnGD

Check your wiring and connectors. Did you leave something unplugged after the work?

You have both temperature sensors acting up at the same time, so I don't think they're both going bad. It may be electrical related. Maybe use an ohmmeter to check the sensors. At operating temp they should read about 200 ohms.

Are both the upper and lower radiator hoses hot when the engine's overheating?

If the lower radiator hose is hot, does the fan come on by itself?

Also, if the fan doesn't come on and if you disconnect the fan switch connection (to make the fan come on), does the temperature begin to drop? (Be careful of moving fan blades!!)

i don't see any unplugged connectors.

the bottom sensor does not read any resistance. however, this is a (supposed) new sensor.

there's another 2-wire sensor that sits in the housing that attaches to the top radiator hose. actually, where the top radiator hose connects to the housing on the engine block, there are two sensors - a 2-wire and a single-wire. The 2-wire reads 200 ohms. The single-wire reads 40 ohms (I place one lead on the sensor connector pin and the other lead I place on the housing.)

the lower hose doesn't not seem to get hot, however, the lower hose connects to the thermostat housing and the thermostat housing gets hot.

the upper hose gets hot.

when the fan doesn't come on and i disconnect the fan switch connection (to make the fan come on), the temperature does not begin to drop.

[Stillrunning]

Originally Posted by drivel60

the bottom sensor does not read any resistance. however, this is a (supposed) new sensor.

First, that's not a "sensor" it's a switch. If your OHM meter is reading "0" then that is the normal reading for the temp switch when below temperature set point. The switch is simply an on/off switch that is normally closed (current flow, OHM reading zero), when it reaches temperature set point it opens (no current flow) and the fans come on. That's why when you disconnect the connector (open circuit) the fans come on.

If manually activating the fans by disconnecting the switch connector does not lower coolant temp then the problem is not fan operation.

Since you changed the thermostat has this corrected the over heat?

[drivel60]

Originally Posted by Stillrunning

First, that's not a "sensor" it's a switch. If your OHM meter is reading "0" then that is the normal reading for the temp switch when below temperature set point. The switch is simply an on/off switch that is normally closed (current flow, OHM reading zero), when it reaches temperature set point it opens (no current flow) and the fans come on. That's why when you disconnect the connector (open circuit) the fans come on.

If manually activating the fans by disconnecting the switch connector does not lower coolant temp then the problem is not fan operation.

Since you changed the thermostat has this corrected the over heat?

thanks for the education.

changing the thermostat did not fix anything. the car never over heated to begin with. my daughter happened to be driving one day and noticed that the temp gauge was moving towards the red and the gauge continues to do so. the temp gauge goes to hot but i'm guessing it's a false reading because there's a problem.

there are three black relays that have the same part number and i've interchanged them with one another with no change in my situation.

also, the wire harness travels from the bottom sensor to a connector that's mounted on another fan. i can disconnect the connector at that point and check the voltage. the voltage at that point (across the connector that leads to the relay box) is ~14vdc. is that normal? is that supposed to be a constant voltage?