Frustrating temp issue!

[PittBuckeye]

My car runs a bit hot all the time and it turns out my fans are not coming on if the A.C. is not on. I have changed the temp sensor, all 3 relays, and the coolant level is good and still no luck. Turn the A.C. on and bingo fans come on. But the kicker is with the fans on the whole time it still goes above the middle line pretty often. I bought the car last winter as a work car for PA. But now I may be working in another state soon and would like to take it with me but I am nervous to drive a long distance if its doing this stuff when driving 30 mins to an hour. Any ideas? 

Edited May 16, 2022 by PittBuckeye

[RX400h]

Here are a few of ideas:

1. Did you check the oil to make sure it is not milky white, which would indicate a possible head gasket leak?

2. When the coolant was last replaced, was the air bled from the system?

3. The radiator could be partially clogged, or water pump could be bad.

[PittBuckeye]

I have owned the car for only 6 months so I don't know if their is air in the coolant. The oil was fine when it was changed 2k miles ago. I've had a blown head gasket before and there are some other indicators which this car does not show. And whether or not the radiator is bad or good I wouldn't think would have anything to do with fans not kicking on when the engine is hot without the ac. But then again I have never come across this so I don't know. The car does not overheat, but it does get hotter than I feel comfortable with.

[RX400h]

I guess you'd have to know the temperature at which the fan is designed to switch on and it would be beneficial to be able to measure the coolant temperature to and beyond that temperature. Without knowing this information, you are just guessing if there is an issue. Do you happen to have a factory repair manual? Sometimes you can find these at reasonable cost on Amazon or Ebay.

[THEBARTMAN]

Have you tried driving on the highway at a steady rate of speed? If there's an issue with the cooling fans, it should operate at normal temps on the highway. If that's the case, just replace both fan motors because they are likely both original, and not strong enough anymore. I would also suggest finding a way to check the actual temp of the cooling system (without removing the cap!) which should average 200-220F when the gauge is steady warm. I use an infrared thermometer and check the radiator, and  where the coolant is flowing in or out of the engine. You can also perform a cooling system flush, replace the thermostat, and ensure that the coolant mixture is no more than 50%. Honestly, If it's not something clear or obvious, you can lose a lot of money throwing parts at a problem. I would take it to the dealer because most service centers have a standard diagnostic charge which is normally around $100.

[PittBuckeye]

You said both motors? I assumed there is only one motor. With the ac on the cooling fans come on but without them they do not. I have driven the car across PA 4 times but everytime it was cold outside so I had the heat on. I haven't changed the thermostat because with the temperature rising even if the thermostat failed the fans should kick on. I believe the only reason the car hasn't overheated is because the water pump and thermostat are doing their jobs. Having the fans working as they should would make things alot better though. But now I'm curious to know if there is more than one fan motor.

[THEBARTMAN]

[PittBuckeye]

Both fans turn on with the ac. If a motor was bad I would assume they wouldn't turn on at all. 

[THEBARTMAN]

Never assume anything.

Electric motors slow down and/or draw more current as they age. 

[PittBuckeye]

Ok I'm intrigued. I found a motor online and it's like 60 bucks. I'm thinking about having it shipped to where I'm working because I'll be here another 3 weeks.