I finally got my coolant temperature sensor hooked up (the one on the pass side of the block), the connector had fallen off the sensor and broke off the wire also. I also did some serious digging around in my battery area and found a connector that wasn't hooked to anything, after even more digging I found my A/C Pressure Fan Switch which was very well hidden under the A/C line above it.

Now that I have the A/C Pressure Fan Switch hooked up to the connector I found, the Secondary Radiator fan is always on when the car's Ignition is on. I have a sheet to diagnose this problem and it's telling me it's one of two things: Faulty Cooling Fan Temperature Switch or Faulty A/C Cooling Fan Pressure Switch.

One possibility it doesn't allow for is, the pressure in the A/C line actually being high enough to ground the fan's relay. Is this in any way possible?

 

How about ignition on, car off. Is the fan on? If so, it's not an over-pressure situation because the compressor isn't running.

 

Yes, with the ignition on, A/C off, Engine off, the secondary fan runs. I'm just wondering if its a bad sensor or if somehow the pressure is staying too high in the A/C line.

 

To have pressure in the AC line, the compressor needs to run. If the fan stays on without a running compressor, the problem cannot be too high a pressure in the line.

 

Thanks Ed. I don't know enough about A/C Systems to rule out that possibility. If I remove that pressure sensor from the line all the freon will escape. Would it be possible for me to convert it over to R134a and recharge it myself without having it evacuated being that there shouldn't be too much contamination with me just replacing that pressure sensor?

Thanks
Justin

 

The A/C pressure switch is a normally open switch. With ignition on, engine off, and fan running (incorrectly), remove the connector from the switch. If the fan shuts off, you need a new switch. If you don't evacuate the system, it won't work as well as it should. Have someone with the correct equipment do the job.

If the fan does not shut off, you most likely have a short in the circuit somewhere causing the thing to stay on.