At Fixya.com, our trusted experts are meticulously vetted and possess extensive experience in their respective fields. Backed by a community of knowledgeable professionals, our platform ensures that the solutions provided are thoroughly researched and validated.
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
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
you are expecting the wrong temperature unit to control the fan. The temperature sender unit controls the temperature gauge and the temperature sensor unit controls the fan operation. It allows current to go to the ECM and when a pre set temperature is reached the ECM activates a relay and the fan starts . Two completely different units to do two different jobs so if it is doing what you say then there is a possibility that the wires are crossed or shorted.
I have similar problem in that my rad cooling fan won't run when hooked up to temp sending unit. Sending unit works okay, displaying what seems like proper temps on inside gauge, rising & falling with engine temp. However, my fan does NOT turn on when wire unplugged from sending unit. Tested fan motor with 12v applied directly & it runs fine, so motor okay.
Haynes manual identified a faulty cooling fan relay (in a situation with your symptoms), which is mounted on the drivers side fender of the engine compartment with 1 other on a support bracket (2 others on same bracket if you have ABS), facing forward toward headlight (NOT nearby ones that are parallel to fender, which has 3 relays on a support bracket). This should work in your case, but didn't in mine.
Several of these close-together relays have the same # on them, so you could swap 2, to see if this is your problem, since normally 2 or 3 relays wouldn't fail at same time. To be sure, I bought a new generic relay of proper # from local auto parts store -- about $10-12 I think -- and installed it in the right place but fan still didn't work. Swapped the 2 relays next to each other (there are only 2 on my forward-facing bracket), both with same #, and still no go.
I'm TOTALLY STUMPED on mine, but yours should work with a functioning relay of proper #. Let me know how it goes.
If anyone has suggestions for my related problem, I'm all ears!
there is a temperature sensor that feeds the ecm(computer)a signal to let it know if the motor requires cooling operation at a predermined temp,which the ecm sends a signal to the cooling fan relay to turn on the cooling fans.when the temp lowers to a predetermined temp the signal is turned off to the ecm and the ecm turns off the signal to the fan relay to turn off the cooling fans.
climate control units in most cars use the ac system to regulate temp in the cab. the ac system requires a fan to pull air over the condensor on the front of the car. its normal for a fan to come on. unless you have a bad engine temp sending unit thats causing the engine cooling fan to come on improperly.
try turning off the heat and ac and see if it still comes on.
When your engine is operating normally, the temp on the gauge should be between 190 and 225. The thermostat is set to open at 190 and this controls minimum engine temp. If you sit in traffic the temp will climb to 225 and then the cooling fan will begin to operate to make sure that you don't overheat.You know that water boils at 212 but you have to add 10 degrees for every pound of pressure the rad cap is set to. Also your coolant has antifreeze in it which raises the boiling point even more. A normal overheat condition of your engine would be 300 or more. Does this help?
The water temp sensor is located near the thermostat housing. This sensor is what tells the ECM to turn the fan on/off. The water temp sending unit is located near the same area. You know you have the correct sensor is because the water temp sensor has a 2 prong plug. The water temp sending unit only has 1 prong.
there is a relay in the junction box under the hood if the cooling fan is not coming on when the engine is at 180 degress you can take the a/c clutch relay and switch it with the fan relay. if the fans come on it's the relay if it still doesn't it's the temp sensor on the fan unit....please rate this
×