Car overheats when the A/C is off?

Hello,

It sounds like only the condenser (AC)fan is running or the fans only run when the A/C is switched on.

Suggest checking cooling fan fuse 57(20A) in under hood fuse block first.
Also check that you have 12V supply to the radiator fan when the AC is switched on.

See good video link below:

https://youtu.be/95CwOqLvuD8

12V should be present at the black/red wire at the 2-pin radiator fan connector.
Also check that you have a good ground connection at the black wire.
This can easily be checked while checking 12V at black/red wire.
First use battery negative to prove that 12V is present, next use the black wire, you should get the same reading on the voltmeter.
See image 1 below.

How to use a voltmeter:
https://www.2carpros.com/articles/how-to-use-a-voltmeter

The other problem might be the radiator fan switch, located at the thermostat housing, lower right rear of engine. See image 2 below.

To test if this circuit is at fault simply disconnect the connector at the fan switch and insert a bridge wire from pin to pin. See if cooling fans run.

Cheers, Boris

Hi,

I noticed we haven't been in touch with you for a few days. Have you been able to make any progress?

I reviewed your original post. The idea that it doesn't overheat with the A/C on leads me to think the fan is running with the A/C on as it should. I have a couple of questions.

With the A/C off, does the cooling fan come on when the engine starts getting hot? Also, does it overheat if you are driving at highway speeds with the A/C off?

Let us know.

Take care,

Joe

Hi,

That is an odd one. I say that because you should be getting more airflow at highway speed than the fan can do.

I attached the wiring schematic for the radiator cooling fans. Let me know if you have already checked the fuses and relay, I highlighted. Note: When checking the fuses, confirm there is power to them.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Also, let me know how the relay was tested.

Take care,

Joe

See pics below.

Hi,

That sounds like it did exactly what it is designed to do. Drive it and don't be afraid; be aware. Keep an eye on the temperature. If you notice it getting too high, find a safe place to park and allow it to cool. Hopefully, it won't.

If anything changes, let me know. Also, if you have other questions, feel free to ask away.

Take care,

Joe

Hi,

I understand. That is higher on the gauge than I would expect before the fans turn on, but the temp you mentioned (217F) sounds normal. Also, the increase in idle speed is by design. It does that to compensate for the added load when the fans turn on.

Have you driven it since yesterday?

Joe

Hi,

If that is where the temperature gauges are staying, it should be fine. I'm not sure where you are located, but if the temperatures are extremely high, the engine will likely run a little hotter.

The best thing to do is drive it and simply keep an eye on the gauge.

Let me know.

Joe

Hi,

Did the gauge get higher than the pics above show? You are certainly in a hot area. However, if the gauge only got as high as shown in the pics, that would be normal considering the conditions.

Let me know.

Joe

Hi,

Since it doesn't overheat with the A/C on, the condenser fan is working. I looked at the temperatures you attached above. In all actuality, they are not out of the norm. The fan may start operating when the engine coolant temperature reaches around 210 to 220 degrees Fahrenheit. You are within that range.

I just don't want to see you spend money and nothing change. Remember, when the A/C is on, the condenser fan runs at all times. With it off, the temp has to increase until the radiator fan turns on. If you are in the range I mentioned, I feel you are okay. Also, since you were at idle in a drive through, the under-hood temperature will increase.

Let me know if you have questions.

Take care,

Joe

Hi,

No problem whatsoever. I just hope I'm helping. Do me a favor. When the gauge goes to its highest point, take a pic and upload it for me. I don't feel there is an issue with the fans, but perhaps there is something going on with the gauge. It's unlikely, but anything is possible. And like you, I like to know everything is okay.

Take care,

Joe