Overheating while running A/C

[beefaroni]

Can anyone who has tun the fan test in INPA comment on whether this is normal behavior?: On a non-M E46 INPA lets you enter a fan speed (%) and will tun the fan at that speed. With the M3 the fan test ramped the fan up to full speed then immediately ramped back down to zero. I am wondering if it is supposed to stay running at high speed until the fan test is terminated.

My coolant temperature increases with the AC on too (no mechanical fan, Spal puller only) and I wonder if the high speed fan relay is working properly.

[yhp2009]

The aux fan is easy to diagnose. Run the car at idle. Once up to temp either the fan comes on or it doesn't.

Debris can clog condensor and rad. Either clean or replace both of them.

Oil temp can influence coolant temp as well. Make sure oil cooler is clean.

Interesting point about the radiator and the condenser. Seems like we always hear about the fans or the thermometer and coolant. But after 15-20yrs i suppose its not a bad guess that the insides of the radiators are corroded and allows for less flow... As well as the obvious outer damages from debris and bent fins.

[eacmen]

The aux fan is easy to diagnose. Run the car at idle. Once up to temp either the fan comes on or it doesn't.

Debris can clog condensor and rad. Either clean or replace both of them.

Oil temp can influence coolant temp as well. Make sure oil cooler is clean.

[NaM3]

I would start off by diagnosing with INPA and use that to see if you can turn on the fan manually. Once you have eliminated the aux fan then check to see if the cooling system is properly bled.

Personally, my problem was the fan clutch, I did all the testing via INPA and the aux fan came on as it should.

[Ramps]

I run my car without the clutch fan, just the aux fan. It comes on when the temp goes over normal OR when i turn the AC on. I don’t know that there’s a hi and low speed, it sounds like it’s all the same speed to me but I could be wrong. How old is your cooling system? It could be sensors or fans or cooling fins that are clogged and letting enough airflow to cool the engine enough but the AC puts it over the top.

[ShaunG]

If your fan clutch has never been replaced there is a very good chance that is the issue.

[SGM330]

Hi Everyone,

I'm trying to diagnose an annoying problem I'm having, especially during the heat wave we're currently dealing with in Toronto. My car is starting to overheat if I'm idling or in slow traffic while using the A/C. I believe it may be my aux fan not engaging into the 'high' mode to keep the car cool. I've noticed that it seems to be running at a lower speed and I was able to catch it running on a higher speed once and at that very moment, the cars temp gauge did not move. Is the aux fan supposed to engage 'high' mode a soon as I turn on the A/C?

I've read it can be a number of things from the aux fan, fan clutch or possibly the coolant level sensor not telling the car to turn up the fan speed. I've also read it can be my thermostat or high speed fan relay (I have no leaks and no other overheating issues).

I just want a little bit of direction or tips on how to diagnose this problem before I start throwing parts at it.

Any insight is appreciated!

Thanks.