radiator fans wont come on

[KEVAUG]

I have a 95 Toyota Camry - 4 cyl DX. The radiator cooling fans are not coming on. I flushed the radiator and tested the fan switch and it is working fine. It opens up at about 205 degrees. The coolant sensor is also good - it read about 3500 ohms at about 45 degrees (cold car). I also tested the 2 relays associated with the fans (the main and fan 1). They were also good. As the temp increases I can disconnect (essentially open up) the fan switch wire and the fans will run. Also if I leave the switch wire disconnected the fans run when I start the car as well. But once I hook up the wire fromthe fan switch to the control it does not come on (essentially a short). Any help would be appreciated. Thanks Kevin

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[toyomoho]

The fans should come on when the A/C compressor is engaged, check for this. The coolant switch is at the bottom of the radiator and set for around 194F. The wiring is setup to work as you described, turning the fan on if the switch wire is disconnected.

If the switch is openning then this should the same as disconnecting its plug (unless a wiring problem). Suggest looking at the switch again.

[KEVAUG]

when I flushed the radiator I removed the fan switch and put it in a pan of hot water with
my OHM meter attached to it. It opened up at about 205 degrees. The toyota manual
just states it should open abouve 199. How can I test the cables?

[pedro]

By disconnecting the fan switch and having the fans run you have proved out the fan circuit except for the fan switch. Doing a continuity check seems to prove out the switch yet the fans don't run. Two possibles: 1. Coolant is not getting to the fan switch. With the rad cold full I would loosen the fan switch to see if coolant flows out. If not then maybe your rad is still blocked on the bottom in which case a rad shop should be able to boil it out 2. Thefan switch is bad but not showing it with an OHM meter. Wells aftermarket switch at Advance or Auto Zone is about $30.

[KEVAUG]

Hi Pedro
I just loosened the fan switch and coolant did come out.
Ihad replaced a few days ago just in case with a NAPA replacement part and it didnt help.
Also today I tried disconnecting the upper radiator hose and poured boiling water
in it to open the t-stat and get any air out of the engine. I never tested the t-stat,
is there an easy way? I just assumed it was fine since the temp gauge on warm up starts to rise and then holds in the middle (I assumed tht is when the t-stat kicked in).
I have never replaced the t-stat. Should I?
Could the water pump be shot? There are no visible leaks but maybe the impeller is broken or free spinning. I'm not to good when it comes to bigger problems.
Thanks

[pedro]

Maybe we're all misunderstanding, is the engine overheating? My fans don't come on unless I sit in traffic and the enginetemp rises. If there is enough air flow through the rad to cool without the fans you're fine. As Toyomoho said they will also come on with A/C switch. Why do you want fans if the engine temp is ok?

[KEVAUG]

Oops, sorry! Yes the car is overheating after about 25 minutes of driving. But if I engage
the fans manually (disconnect the connector from the fan switch) the cars seems to be OK. Since I tested the fanswitch and it was good, it appears the hot coolant isnt reaching the fanswitch? But when I loosened the fanswitch on a cold engine coolant did come out of the radiator. I did flush the radiator myself.
Thanks

[pedro]

Overheating by how much? The gauge sender is before the rad on the coolant outlet of theengine - the hottestspot for coolant, the fan switch is located on the bottom of the rad after the coolant has been cooled by the rad. If your gauge measures higher temps that does not mean the fans need to activate as the rad may havereduced the coolant temp enough to be below the set point for the fan switch. You still mayhave a problem though as my temp gauge never moves above justbelow midpoint mark. 25 minutes of driving how, where, speed?

[toyomoho]

The Camry has a very good cooling system, thus unless it has a problem the temp gauge needle should stay in the same spot.

As to the coolant temp switch, the switch should turn off (become open) at around 194F (manual states 199F). Once the circuit is broken the No 1 fan relay should engage along with the fan. As the fan turns on when the plug is removed from the switch (circuit broken) would seem this circuit is OK. All that needs to happen is for the switch to open and close.

You might remove the radiator cap and place a thermometer in the coolant. Determine if the coolant is reaching the temp required to turn the switch off.

[KEVAUG]

Hi guys
Yes the temp gauge is pegged. I only noticed it because I heard it boiling when I shut the car off. I live in CT and it was cold. Last I took it out on the highway about 20 minutes and it started to raise the temp. I can pull over and manually turn the fans on and it cooled it down. I put a new radiator in it in 2004. I did use a bottle of stop leak prior to replacing the radiator. When I did the radiator flush the water was brown (from rust I suspect).
It burns about 1 qt of oil every 3000 miles.
Thanks for any advice.
Kevin