Help with Overheating 1997 Camry

[a1parrothead]

I will try and be brief, but I need help. 1997 Camry with 4 cylinder, automatic. Overheated the other night and temp. gauge pegged. With engine still running I opened hood and noticed instantly that the electric fans were not running. Fan problem? Checked fuses and relays best I could. Found nothing. Read on internet that the fan cooling sensor that's on the bottom of the radiator could be bad. Said that if I unplugged it and the fans came on, it was faulty. I unplugged it and the fans came on( If the fans come on that tells me it's not a fuse or relay problem). So I replaced the sensor. Started the car and it overheated and the fans never came on. So I made the fans come on by 2 different ways. One way was by turning on the A/C. The other way was by unplugging that sensor again. By doing either one the fans come on. I do not have to do both.
PROBLEM #1-So basically, the car overheats and the fans never come on by themselves.
So I put in a new thermostat. Car overheats. So I flush entire system. Car overheats. I look and try and see if water pump is leaking. Does not look like it. Water pump does not make noise. Still suspicious of water pump because I do not see a lot of water flow through radiator and when I squeeze top radiator hose I do not feel a lot of circulation. So water pump? Clogged radiator?
Problem #2- If radiator is clogged or the water pump is bad and the car overheats, WHY ARE THE FANS NOT KICKING ON?! Should the sensors not register the car getting hot and at least trip the fans?
Problem#3- More confusing. Now I start the car and it starts to overheat. So, I use my trick of turning on the A/C to make the fans run. They do. But only for a few minutes, then they shut off and the car begins overheating. Why did they shut off?
I have thought about a head gasket. No water in oil, no oil around filler cap, no sweet smelling exhaust, no power loss etc., etc. What is the problem? Another sensor? Any ideas would be great.
Thanks, Jeff

[reluctantmechanic]

Originally Posted by a1parrothead

Any ideas would be great.
Thanks, Jeff

Oddly, I noticed my mothers 5sfe top radiator hose was "collapsing" on itself, causing the flow of water to the radiator to stop - I replaced that top hose, and everything has been fine.

Sometimes the fans can go bad, or a bad fan relay?

[Mister_Perkins]

why is your font so freakin huge????

[doozergreengrass]

OP are you loosing coolant? Head gasket/head problems can cause vapour which could cause the fans to not turn on.

[yotaforce]

Try sticking a thermometer in the radiator fill while its cold then running it till its hot. if around 190 +/- 10 degrees the thermometer jumps to said temp then things are circulating fine. As for your problem #3 the a/c fan only runs when the low pressure switch (located in the a/c system and nothing to do with the coolant) tells it to its for the condenser but the radiator gets the air too. You might try checking the grounds on the fans... they might run on a different one when the switch is defaulted. best of luck mane.

[yotaforce]

oh and one more thing.... a really awesome way to check for head gasket leaks with out the expensive color changing magic liquid is put the little tube coming from the top of the radiator fill neck, to the overflow tank in a cup of water and look for bubbles

[JohnGD]

If you turn on the A/C then the engine never overheats? I think you may have answered your own question.

If the ECT switch is new, then it may be that the "hot" coolant never reached the switch. Verify using a thermometer as mentioned. You may need to get a new rad, but verify before you start to replace parts.

Originally Posted by a1parrothead

So, I use my trick of turning on the A/C to make the fans run. They do. But only for a few minutes, then they shut off and the car begins overheating. Why did they shut off?