Radiator fans wont come on

[sugaryling]

It turns out that when I turn on the AC, both fans will come on. Does this mean that all fuses are okay? If the fuses are okay, then which relay should I look at next?

[sugaryling]

I remove the panel cover and I see no fuses. The diagram you posted below doesn't look like what I have in the car. All I see are relays.
This is what I see:



Am I looking at the wrong panel? Is there another one?

[audiqv8]

Originally Posted by sugaryling

It turns out that when I turn on the AC, both fans will come on. Does this mean that all fuses are okay? If the fuses are okay, then which relay should I look at next?

If the fans run then your fuse is OK. You will have to verify that the temperature sensor located at the bottom of the radiator is good. If you have a non-contact infrared thermometer then check out the temperature of both radiator hose once the engine get up to operating temperature. This will verify if you have a clogged radiator. It appears that you and dubblrest1985 might have the problem.

[sugaryling]

The fans will ONLY run when I turn on the AC. They still won't turn on when the car gets too hot. I keep the ac running on low when I'm driving on local streets or traffic just to keep the fans on. This way the car wont over heat.

I'm pretty sure the radiator isn't flowing 100%. It is a 1997 car with the original radiator. If the fans would just turn on when the car gets hot then I wouldn't be over heating. This leads me to think that the radiator isn't clogged to the point that it's not functioning...yet. I don't own an infrared thermometer but will try to borrow one and check the hose temps and report back.

I also called the dealer for the high and low speed fan relays and I was told that there is only one relay in location #3 in the fuse box under the hood. It's close to $60 so I bought an aftermarket one for $20. The new relay doesn't turn the fans on when the car is too hot. So the original relay wasn't bad at all. This relay is 70amps! WOW!

I should've picked up a new fan switch at the same time. I really though the new relay was going to fix my problem...back to the drawing board. lol

[audiqv8]

This is a way to test the radiator temperature sensor

The coolant fan control thermal switch is located in the lower left part of the radiator.

Terminal assignment 3-pin connector
Pin 1 = 1st stage
Pin 2 = 2nd stage
Pin 3 = Battery ground (B-)
Switching temperature:
Pin 1:
On: 92-97°C (198-207°F)
Off: Approx. 84°C (183°F)
Pin 2:
On: 99-105°C (210-221°F)
Off: Approx. 91°C (196°F)

Testing Procedure

1.Place sensor in a suitable container of liquid that contains a thermometer an may be heated and cooled.
2.Connect a suitable ohmmeter or continuity tester to terminals one and three of the sensor to test the 1st stage circuit.
3.Heat liquid while observing thermometer and continuity tester, circuit should close between 92-97°C (198-207°F) .
4.Cool liquid while observing thermometer and continuity tester, circuit should open below Approx. 84°C (183°F) .
5.Connect continuity tester to terminals two and three, then repeat above procedures to test 2nd stage circuit, noting the following:
6.Second stage circuit should close between 99-105°C (210-221°F) .
7.Circuit should open below Approx. 91°C (196°F)

Or you can remove the wire to the sensor and short out pins 1 and 3 to get the fan to come on. This will cause the fan to run at (low) stage 1. If the fan comes on then you either have a bad radiator temperature sensor or a clogged radiator.

[sugaryling]

Fans come on now! It's the fan thermo switch sensor located on the lower radiator. I removed it from the radiator and I expected coolant to come pouring out. It didn't! So I stuck my finger in the hole and poked around a little and felt a lot of sediments. I started to dig out the sediments and then the coolant poured out as it should.

So, the problem was either a bad fan thermo switch sensor or there was way too much sediments sitting in the lower section of the radiator (which there was) that the sensor couldn't read the coolant temp. Or both! I replaced the sensor with a new one. $8 fixed the problem...unfortunately I had to spend over $500 to find that out.

Thanks for all the help!

[upallnight]

Sounds like you had a clogged radiator as pointed out by audiqV8.

[sugaryling]

I don' think my radiator was clogged to the point that it's not functional. I say that because it doesn't over heat on the highway when I'm not in traffic. It also doesn't over heat when the fans are on. I'm sure the radiator is clogged a little since it's original.

Most of the sediments must've come from the heater core. I had no heat and when I ran a hose through the heater core a lot of sediments came out too.

Once again, big thanks to the forum for all the input! Especially "audiqv8."

[gcpgcp]

I am reading this thread with interest, thank you for all your information!!

I found the other day that my coolant expansion tank is cracked and leaking so it must be replaced but could lack of pressure cause the thermostat to remain closed? The lower hose remains cool to the touch while the upper is hot so I am thinking I may have a bad thermostat, a bad water pump or a bad sensor. How do I verify which is the actual culprit? When AC is on the fans turn properly but will not turn on otherwise.

[sugaryling]

I may be wrong but the thermostat operates only on coolant temp and pressure has nothing to do with it.

If your expansion tank is cracked and leaking, replace it.

If your fans don't turn on, I would suggest you replace your fan thermo switch like me. It's cheap and if that doesn't fix the problem...you only waste $8.