2004 T&C, 3.3L, A/C is manual 3-zone

When the A/C is on, the radiator fans don't come on. Like, not at all ever. The pressures and liquid line temp get fairly high and keep creeping up. Like 50/250 psi at 50F ambient after 3-4 minutes.

There are no leaks in the system and the pressure transducer works fine. Any idea as to why the PCM doesn't turn the fans on? The fans do kick on when water temp gets high enough.

Any ideas appreciated.

 

Does the A/C compressor come on with A/C turn on? You could have a bad fan relay. Thats mount on the front bumper on the passenger side. If you have access to a DRB3 scanner, actuate the fan and see if it comes on. If it don't the relay is most likey your cause.

 

Yes the compressor comes on.

The fan relay is fine, it turns on the fan when the engine water comes up to temperature.

 

Ideas, anyone?

 

The condenser fan does not turn on until system high side pressure reaches 250psi. Try it when it gets warmer outside and the pressures get higher. With cooler outside temps, it is not uncommon for the fan not to run.

 

It did reach over 250 psi after a few minutes running, when I had a manifold set connected. The pressure transducer put out about 2 volts at that point. Fans didn't come on.

 

Couple of thoughts. First the AC fan relay in the fuse box under the hood, check it out. If the temp sensor was bad you would not have fans at high temp so that is good, and obviously the fan motors are good.

 

I would need an actual temp reading from a scan tool to tell for sure.

 

Which temp? IAT? There is no refrigerant temp sensor.

 

Sorry, high side pressure reading from the transducer.