Radiator Fan or Condensor Fan? Boiling Coolant with AC on

[Chris_s1]

The fan on the passenger side, inside of the lock carrier. That'd be the radiator fan, not ac condenser fan correct? My car is overheating when I turn the AC on, coolant is boiling over. That fan does not turn on.


Thanks,
Chris

[Chris_s1]

Anyone?

[Skianddestroy]

if I'm not mistaken the fan you are talking about(pass side, inside lock carrier) IS your a/c fan. On my AR, I had the same prob, fan wasn't turning on. I found out the fan was bad after I connected it to my battery and it still wouldn't turn on. The plug for your fan is right next to your PS reservoir on drivers side. Connect it to your battery using wire and jumper cables. This will be the easiest and first thing you should do before replacing any switches, relays ect. You could just need a new fan. I got mine for $30 something

[G0to60]

The fan behind the radiator on the passenger side is the AUX fan and will come on with the AC and/or if temps get warm. The fan in front of the radiator on the drivers side is the AC fan and comes on with the AC. It will also go to high speed with the AC on when the temps get high. Both are connected to the controller, as Skianddestroy said, on the drivers side by the power steering reservoir.

[Skianddestroy]

Just curious if all the 2.7t's have 3 fans or just the AR, not sure what Chris' car is but if he doesn't have the 3rd in front then won't have the "air raid" fan to compensate

[Chris_s1]

Thanks to both of you. Car is a 2.7t sedan, not AR. So that means the fan that needs replacing is the AUX fan. There are two fans behind the radiator (or inside the lock carrier), and one fan in front of the radiator towards the drivers side. When the car is turned on, the radiator fan (drivers side, inside lock carrier) turns on. When the AC is turned on, the fan in front of the radiator (drivers side, outside lock carrier) kicks on after a while. Not immediately. The fan on the passenger side behind the radiator (inside lock carrier) does not turn on at all.

I'm in Miami, and it's hot here. Still 85-95 degrees during the day. My coolant only seems to boil over when the AC is turned on. At no other time do I have any issues.

[rollerton]

The passenger side fan runs off the pulley, so it's just going to spin around lazily most of the time. The other two fans are electric, should run or cycle with A/C. They're both super easy to replace, but if they run or cycle regularly or at all they're probably fine, and that usually eliminates the fan module also, but you usually get an error when that fails.
So you're left with unlucky and super unlucky situations.
#1. And I'd say more likely is the thermostat is stuck/ failed.
#2. Is bad headgasket.

Just went through this a month ago. After you've driven the car and parked it let the engine cool down to some extent, maybe 15-30 minutes if it was pretty hot. Then go out and open the coolant reservoir slowly and listen for the pressure release. If you hear a decent amount of pressure *hisssssssssss* from the reservoir after the car has sat for more than 15 minutes than you're probably looking at the thermostat. If the headgasket was leaking the pressure in the system would typically leak off after sitting a bit.

If you open the reservoir and no *hisssssss* then ..you might look into a leak-down test to make sure the headgasket isn't bad.
Just a couple ideas. I mean, radiator clogged or failed water pump?
But those two I mentioned are where I'd start.

[Chris_s1]

Thanks Rollerton. I had considered that it was a bad headgasket but I don't have any of the typical symptoms such as white smoke, milky oil, etc. But it could still be possible. I also replaced the thermostat +-1 year ago when I did the timing belt, so I was hoping that was not the problem.

I'll drive it and crack open the reservoir like you said and we'll see where I stand.