TEST 2: Electric Fan Motor Operation
Your 2.0L, 2.4L Chrysler vehicle is equipped with an electric fan motor and since you still have your scan tool connected to the vehicle (from the previous test), I'll show you how to check to see if the fan motor is coming on at the correct temperature.
Before you start, you need to make sure that the A.C. is turned off.
Alright, this is what you'll need to do:
- 1
Restart the engine in your car and continue checking the coolant temperature your scan tool is registering.
- 2
Let the engine run till the coolant reaches 225° F (107° C), as registered on your scan tool.
At 225° F, the fan should com alive and start cooling down the coolant. - 3
If the fan motor has not turned on by 227° F (108° C), turn off the engine (any temperature above 300° F and the engine is considered to be overheating).
- 4
As the fan continues to run, you should see that the coolant temperature (on your scan tool) start to gradually decrease till it reaches 200° F. At this point, the fan should turn off and the cycle will repeat itself.
Let's interpret the result of your test:
CASE 1: The fan (or fans) did NOT come on at 225° F - 227° F. This test result confirms that the overheating problem is due to a fan motor issue.
Now, it's beyond the scope of this article to further test the fan motor, but at least now you know that you do have a fan motor issue. The next steps are for you to test the fan motor, fan motor relay and fan motor fuses.
CASE 2: The fan (or fans) did come on at 225° F - 227° F, but the vehicle continues to overheat. If you have also confirmed that the thermostat is good (in TEST 1), then the most likely cause of the overheating issue is a blown head gasket.
You can find three specific tests, to verify a blown head gasket in this article:How To Test For A Blown Head Gasket (Chrysler 2.0L, 2.4L).
CASE 3: The fan (or fans) did come on at 225° F - 227° F but the temperature DID go down. This confirms that the fan(s) and thermostat are OK. No further testing is needed.
Engine Thermostat Basics
In case you're wondering why the engine has one and needs one, this section might shed some light on the subject (don't worry, I won't go into minute technical mumbo jumbo).
In a nutshell, the thermostat's job is to help regulate the engine's temperature. The PCM needs to have the engine within a certain temperature range to effectively control the emissions that the engine produces and to help you get the maximum amount of gas mileage possible. This temperature range is between 190° to 225° Fahrenheit (87° to 107° Celsius).
The reason for this is that the cooler the engine is, the more gasoline it needs to keep running smoothly (and unfortunately, at these temps, it pollutes more). As the engine heats up and reaches the optimal temperature range described above, the engine needs less and less fuel to maintain it's optimal performance and of course pollutes less.
In a nutshell, here's how they both keep the engine from overheating and running optimally:
- 1
The thermostat is the one tasked with keeping the engine from going below 190° Fahrenheit.
- 2
The fan motor (or fan motors) are tasked with keeping the engine below 227° Fahrenheit.
- 3
When you start your vehicle, the thermostat is closed, thereby keeping the coolant from circulating to the radiator. This allows the engine to warm up faster.
- 4
As the coolant circulates in the engine only, its temperature increases and when it reaches 190° F, the thermostat opens.
- 5
With the thermostat now open, the coolant can now circulate between the radiator and the engine.
- 6
Even tho' the thermostat has opened, the temperature of the coolant will continue to increase. When the coolant's temperature reaches 227° F, the fan or fans come on.
- 7
The fans will bring down the temperature of the coolant (inside the radiator) which is circulating to the engine (due to the open thermostat). Once the temperature decreases down to around 200° F, the PCM then turns off the fan or fans.
Continued in the next page.
