Humor me: A/C delete question.

[CorvallisBMW]

Compared to the main clutch-type engine fan, the aux fan puts out very little air. If your car is overheating with a properly working fan clutch I doubt the aux fan is going to make a difference, especially since they're blowing towards each other which (I think) would be less efficient than blowing in the same direction.

[SpecM]

especially since they're blowing towards each other which (I think) would be less efficient than blowing in the same direction.

they DO blow in the same direction...

[dnova89]

^I think he means the aux fan blows towards the condensor... the clutched fan blows towards the radiator. The clutched fan is behind the radiator, the aux fan is in front of the condensor.

Kidneys/front of car | Aux fan --air--> Condensor | Radiator <--air-- Clutched Fan | Motor

I don't see why the aux fan would make the clutched fan less efficient... the only reason I can see is that once the air passes thru the radiator and becomes hot air, the aux fan might blow the hot air right back to radiator?

[u3b3rg33k]

But what are you losing by keeping the aux fan? One of the worse feelings in the world IMO is watching your temp gauge slowly creep towards the red while you're stuck somewhere you can't turn the car off (traffic). Keep the aux fan and enjoy complete peace of mind.

gas + clutch = more airflow = lower temps. works every time (unless your fan clutch is bad)

^I think he means the aux fan blows towards the condenser... the clutched fan pulls towards the engine. The clutched fan is behind the radiator, the aux fan is in front of the condenser.

Kidneys/front of car | Aux fan --air--> Condenser | Radiator --air--> Clutched Fan | Motor

Fixed that for you.

[ChaseN]

gas + clutch = more airflow = lower temps. works every time (unless your fan clutch is bad)

Unless your thermostat is bad (i.e. stuck open), and the reason it's overheating is because water isn't being allowed to stay in the radiator for enough time to actually cool. SO then, gas+water pump = water going through radiator even faster, and clutch fan STILL not keeping up. I played around with it for a minute, and found leaving it at idle with the aux fan going + the heat on full blast kept it cooler longer. Just barely long enough to get me out of the tunnel into open roads.

[Philo]

I've never had my m20 get close to the 3/4 mark, so the aux fan has never ran. I still find the aux fan to be unnecessary in this situation.

[Dirty e30]

I've never had my m20 get close to the 3/4 mark, so the aux fan has never ran. I still find the aux fan to be unnecessary in this situation.

are you sure it has never run? it should kick in at about the half way mark (at least mine does)

Compared to the main clutch-type engine fan, the aux fan puts out very little air.

i'm only running an aux fan and have never had any problems with cooling. if corvallis is right, seems like the clutch fan should be enough.

[u3b3rg33k]

Unless your thermostat is bad (i.e. stuck open), and the reason it's overheating is because water isn't being allowed to stay in the radiator for enough time to actually cool. SO then, gas+water pump = water going through radiator even faster, and clutch fan STILL not keeping up. I played around with it for a minute, and found leaving it at idle with the aux fan going + the heat on full blast kept it cooler longer. Just barely long enough to get me out of the tunnel into open roads.

That's so very, very wrong. Heat transfers regardless of how fast the water moves through. if the water is moving faster, the delta T may be lower, but more water will be put through and the entire system will be at a more even temperature.

Engines with stuck open thermostats typically never reach operating temp.

Maybe you need a new fan clutch.

[Kershaw]

i ripped out the aux fan along with the condenser in the e30 i gave my girlfriend. i drove it for 7 months and never once had a problem.

[TwoJ's]

That's so very, very wrong. Heat transfers regardless of how fast the water moves through. if the water is moving faster, the delta T may be lower, but more water will be put through and the entire system will be at a more even temperature.

Engines with stuck open thermostats typically never reach operating temp.

Maybe you need a new fan clutch.

I sense that you've taken a thermodynamics/heat transfer course?


OP, I would take Jean's advice and keep the fan and use those brackets. A properly sorted cooling system likely won't need it, but it is cheap insurance in my opinion. It's not heavy, and doesn't get in the way of anything for you, so I'd keep it.

[HarryPotter]

If it works keep it, if not toss it. I have mine jerry rigged on lowspeed (shoulda made it highspeed) so that it cools my condenser. I do have working A/c, it is great.

[Sagaris]

Thanks for the input everyone! I will need to test the aux fan to see if it runs, I may end up wiring it to the A/C switch to be able to switch it on and off as I please.

[ChaseN]

That's so very, very wrong. Heat transfers regardless of how fast the water moves through. if the water is moving faster, the delta T may be lower, but more water will be put through and the entire system will be at a more even temperature.

Engines with stuck open thermostats typically never reach operating temp.

Maybe you need a new fan clutch.

Sure, whatever you say pal. Out on the road it would sit at the top of the blue. At idle in HOT ambient temperatures it would overheat like a mofo. Put a new thermostat in (old one was stuck open) and it doesn't happen anymore.

Your explanation might work in physics class, but in the real world, with often less-than-perfect system conditions, it doesn't. Google around a bit, read, and see what you come up with. You'll find I'm not the only one who has experienced overheating from a stuck open thermostat...

BTW my fan clutch is fine, and with my new thermo, I no longer get hotter than a needle's width past the middle even idling for 30 mins+ in traffic trying to get through one of Pittsburgh's tunnels. I am going through the whole system and replacing mostly everything though, as its a 105k mile 20 y/o car that I know little to nothing about past the last 5 years. It'll be great peace of mind.

[u3b3rg33k]

Sure, whatever you say pal. Out on the road it would sit at the top of the blue. At idle in HOT ambient temperatures it would overheat like a mofo. Put a new thermostat in (old one was stuck open) and it doesn't happen anymore.

Your explanation might work in physics class, but in the real world, with often less-than-perfect system conditions, it doesn't. Google around a bit, read, and see what you come up with. You'll find I'm not the only one who has experienced overheating from a stuck open thermostat...

BTW my fan clutch is fine, and with my new thermo, I no longer get hotter than a needle's width past the middle even idling for 30 mins+ in traffic trying to get through one of Pittsburgh's tunnels. I am going through the whole system and replacing mostly everything though, as its a 105k mile 20 y/o car that I know little to nothing about past the last 5 years. It'll be great peace of mind.

Sounds more like a thermostat that failed to open all the way. Usually happens when the seal fails and some of the wax leaks out.

[Need4Speed1299]

If your fan/clutch works fine you probably will be just fine w/o aux fan. Plus you are in WI, not in CA,AZ,TX,FL....

It can get really hot here during the summer though.

I would suggest running a colder thermostat. If you idle for more than about 2min on a hot day, the engine will start to get really hot. Im doing an a/c delete soon and plan on wiring up a switch for the aux fan to fix this type of situation. Get those brackets and use the one you have.