The fans will come on but not stay on long replaced relays allready also temp gauge pegged out at 260 but no check engine light and radiator was not hot could take cap off water was hot but didnt burn could touch it and fans didnt come on temp gauge usually is around 185-200 but when this started guage will go to 230 or peg out
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Re: cooling fan problem
The electric fans on some vehicles dont stay on all the time. If the radiator is not burningyou then i would suspect the guage is bad. The engine would throw a code if the fan was not working properly, so im pretty sure that your fan is working properly. I hope that helps you out.
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A pontiac montana ? There are three relay's that control your cooling fans ! unplug what sensor ? The engine coolant temp. sensor is an input to the PCM - engine computer . When temp. reaches 213 degrees the PCM energizes the relays , depending on low or high speed . Using a scan tool to see if the PCM will turn on the fans an checking engine coolant temp.data is the right way to diagnose this . Relay Driven Dual Cooling Fan Diagnostics
Did you check the fan relays ? There are two, cooling low relay an cooling fan high relay . The relays are turned on by the vehicles PCM - engine computer , when an input from the coolant temp. sensor indicates a certain temperature ! When you turn on your A/C the cooling fan should turn on an stay on . Relay Box
Left center of engine compartmentCooling Fan High Relay
In relay boxCooling Fan Low Relay
In relay box
Do you know how to test a computer controlled relay ? Go to you tube an search relay testing . Does the temp. gauge work correctly ? I know you probably don't have a factory scan tool , but this is the where I would start , checking temp. sensor input to the PCM . An with a factory scan tool I can do bidirectional testing , see if I could turn the fans on will scan tool .
if it over heats when stationary but cools down when moving , that is an indication of a cooling fan problem
If the engine has a viscous fan hub ( fan clutch) replace it as it is not spinning hard enough when stopped to draw air through the radiator
If it has electric fan/s check why it is not working at engine temperature --could be the coolant temperature sensor ( not gauge sender unit) that is faulty and not telling the ECM to turn on the relay for the fan/s or a bad fuse or relay that is not completing the power circuit
Unplug the fan on sensor. It should have one green wire and one black wire. Use a paper clip and jump the two wires. Turn the key to the run position, the engine does not need to be running. Does the fan come on? If not check the green wire for 12 volts and the black wire for ground. If there is no ground than run a new ground wire. If the is no power check the heater/air conditioning fuse in the under dash fuse block. If there is power and ground make sure both the cooling fan fuses are good and both the cooling fan relays are good.
CHECK FOR LOW COOLANT.YOUR CLUTCH FAN COULD BE BAD IT CAUSING ENGINE TO OVERHEAT.WHEN ENGINE GET HOT THE SILICONE OIL IN FAN CLUTCH GET HOT CAUSE THERMOSTAT SPRING EXPAND CAUSE FAN CLUTCH TO LOCK IN TURN FAST WITH ENGINE TO COOL OFF ENGINE. IF FAN IS WOBBLY OR FREEWHEELING ITS BAD.
It sounds like your cooling fans are not comming on by themselves, but when you turn on the ac it forces them to turn on. Make sure relay is good, then replace coolant temp sensor, this may have failed no telling pcm to turn on cooling fans. Thanks
The only real way to answer your questions is for you to open the hood and look it over. Once it has cooled down, re-fill the cooling system (use water...it's cheaper and to do repair you will need to repalce it anyhow...Once full carefully look everything over to find where the leak is.Also make sure that the drivebelt is there. (from what you said, likely it is) If it's water pump, you will see coolant running out from under the pulley. Once you have looked everything over, if you have not found leak, start engine and close the cap...look again...as pressure builds, small leaks will become more obvious. If you don't find leak, remove the thermostat and change it. After changing stat, if problem persists, it's likely that you have either a plugged radiator or an internal engine gasket problem. If you have any auxiliary electric cooling fans, make sure they are working and also check the fan clutch on the mechanical fan (it should not excessively freewheel when hot). Whole testing, any time you replace the radiator cap you must allow engine to cool down before removing it again. Watch temp gauge while testing...don't allow engine to overheat.
When the GC reaches a temp of 180 Deg. F the fan relay sends a signal to the fan to turn on, once the temp lowers (around 155 Deg. F) the relay turns off the fan, and so the cycle continues. If the relay is bad there will be no signal to the fan to run. While you are driving your vehicle there is ambient air moving thru the radiator, cooling the engine, but once you encounter slow/heavy traffic or stop there is no air moving and the temp goes up, the fan will not kick in and the vehicle will overheat.
If the fan motor is not working the same will happen, but a more expensive fix, as the motor comes with the fan.
If the Thermostat is stuck in the open position, the water travels to fast in the engine and heat exchanging is not an efficient process, therefore the vehicle might overheat when stopped or in slow traffic.
hey if it was constantly running at these temps you would dhave definately damaged the engine by now. the temp guage is integrated with the instrument cluster and not replaaceable unless the whole guage cluster is replaced. you could go to a professional installer and have an aftermarket temp guage installed. much cheaper than having your instrument pannel replaced. in addition to the instrument pannel being replaced the odometer millage must be programed into the new pannel. if the fans are not turning on the engine more than likely is not getting hot enough to turn them on. but just to be sure i would take the vehicle to a automotive diagnostic specialist to make sure the ecm (electronic control module) is performing correctly. it may not be sending the signal to the fan relay to turn the fan/ fans on. you may also have a faulty temp sending unit. good luck. SMB......
couple posabilities first run car up to temp then turn off...when fan stays running unplug the coolant temp sensor for the fan< there are 2 other is for comp/gauge> if fan turns off replace sensor if not replace relay for cooling fan