Radiator Fan running all the time

[jjager2385]

hi,
I have a 1995 Chrysler Town and Country that the Radiator fan is running all the time when the motor is running, i have been shown that if i remove the electrical plug on the high side of the A/C then it will turn off, i have replaced the sensor on the high side of the A/C but that didn't change anything. was wondering if anyone else had any suggestions or maybe have had the same experience and how they fixed it.

Thanks in advance.

[carsandcycles]

If the a/c is on, regardless of engine temperature, the fan is going to run; is this the condition you describe (or do you have a fan run when a/c is off)?

[thcardoc]

The first thing you need to determine is whether the PCM ( powertrain control module) is commanding the fan to run or if there is an issue in the control circuit for the fans. Unplugging the AC high pressure switch while an attempt to see if the fans are being commanded that way isn't the right way to go about this. You need a scan tool that can display all of the data from the PCM. With the scan tool you can first look at the engine temperature that is being reported and then take steps to confirm accuracy, and you can look for AC clutch request, and then command data pids, and then of course move onto the cooling fan controls.

The reason you have to look at all of this is to be certain if the fans are running for a legitimate reason or not. There are a number of trouble codes that if set will cause the PCM to run in a back-up mode and commanding the cooling fans on if the PCM isn't really sure what the engine temperature is would be one of them.

The AC high pressure switch (sensor depending on your system design) is an input to the PCM for the potential need to operate the fans. Scan data should show if that input is such that the fans should be commanded or not.
Have you connected gages to the system and measured the high side pressure? Does your AC work correctly? Has anyone tested the system by measuring the surface temperature of the high side components at various locations in order to see if the system has a restriction? The AC high pressure switch contacts should be open below 160psi, (fans off) and close no higher than 230psi (fans come on).

Another thing that a proper scan tool can do is use bi-directional controls and allow a technician to take control of the circuit to see if the PCM would command the fans to operate correctly provided the PCM had the correct inputs.

[justen]

CNC is correct. A/C has a internal trip switch, when A/C is on. The fans should be also. If the radiator fans are not on. You have issues. These fans on or off will not effect fuel mileage. You can even run one on a square alarm clock 9 volt battery.

[thcardoc]

Originally Posted by justen

CNC is correct. A/C has a internal trip switch, when A/C is on. The fans should be also. If the radiator fans are not on. You have issues. These fans on or off will not effect fuel mileage. You can even run one on a square alarm clock 9 volt battery.

Are you sure about that?

[3boystoys]

Had a Dodge that did this, fan relay had welded itself together. Filed the contacts and fans worked fine.

[justen]

Originally Posted by thcardoc

Are you sure about that?

Yes I am. I can test them to see if it's dead or going to spin. Cellphone batteries also work. The one I use its a 9 volt out of a old samsung phone.