At normal outside temps, if I remember correctly the fan should not run or be running. It only ran when the a/c was operating and then every once and a while. I replaced the thermostat housing with a new one that included a new thermostat and fan sensor because of a crack in the housing. There doesn’t seem to be a flow problem anywhere else. The fan still seems to be operating more than normal. Am I nuts? Is there something I’m missing?
what year car?
All you need to do is determine at what coolant temperature that the sensor causes the fan to operate.
Then with an infra-red thermal gun, point it at thermostat housing to see if the coolant is at that temperature.
If not, might have got a bad temp sensor for the fan.
Tester
"At normal outside temps, if I remember correctly the fan should not run or be running."Wrong
"Am I nuts?"I'm not qualified to answer that.
"Is there something I'm missing?"Yes. The fan cycling on/off is not dependent on the outside temp., the coolant temp determines the fan cycles. In other words the outside temp could be 150*F but if the coolant temp never reaches the cut on temp usually somewhere between 190*-220*F the fan will not come on.
The car is a 2006. The digital temp gauge in the car reads in the normal operating zone so the thermostat must be ok. I need to have the sensor checked. I don’t have that equipment mentioned by Tester. Thanks
The temp sensor for the dash indication is different for the fan operation.
What you replaced was for fan operation.
Have you tried installing old temp sensor to see if it makes difference? If you still have it?
Tester
If the fan is cycling on and off and the engine is operating in the normal range, you probably don’t have a problem. One simple thing to check is the fins on the radiator to make sure that bugs haven’t blocked the airflow through the radiator. If insects have partially blocked these passages, the fan will run more often to keep the coolant at its normal operating temperature. Forcing water through the radiator from the engine side out or blowing the passages clean with an air hose should take care of this problem.
If the fan is cycling on and off and the engine is operating in the normal range, you probably don’t have a problem. One simple thing to check is the fins on the radiator to make sure that bugs haven’t blocked the airflow through the radiator. If insects have partially blocked these passages, the fan will run more often to keep the coolant at its normal operating temperature. Forcing water through the radiator from the engine side out or blowing the passages clean with an air hose should take care of this problem.
My Corolla’s radiator fan only comes on when doing low speed driving or idling, like say waiting in line at the drive-through. Down the road at 35 mph or faster, the air through the grill is enough to keep the coolant temperature in check.
You could try this experiment, easy enough to do. Start with a cold engine in the morning, before the car has been driven for the day. Start it up but don’t drive it. Let it idle in the driveway. AC off. Monitor the dash temp gauge while you do this. The fan shouldn’t be on when the engine is cold. Record how long after the idling started and what the dash temp reads when it turns on. And the same for when it turns off. Let it cycle a few times to see if it is turning on and off at the same dash temperatures.
It’s probably controlled by a temperature sensitive switch. I had that switch go bad on my Corolla a couple of times. Sometimes the fan would turn on then never turn off. Other times the fan wouldn’t turn on when it should, which is a worse symptom as it can damage the engine. What I did was unscrew that switch, put it in a pan of hot water on the stove, with a thermometer and a DVM, and measure the on resistance, what temperature the switch switches, both as the temp is rising, and as it falls.
In my case the switch had a high resistance when on (about 30 ohms, should be less than 1), and it was turning on and off at inconsistent temperatures, varying by 40 or 50 degrees one time to another.
Dirt and stuff in the radiator and a/c fins has to be my problem… Lots of road grit, dust etc where we are. I’ll try that first. Thanks for all the tips.
Sounds like a good plan. Don’t direct a full force of water from a garden hose at those fins though, in some cases that will bend the fins and make the problem worse. I learned this the hard way.