Overheating while running A/C

[eacmen]

No brother. If you read the past posts on this thread i mentioned removing my BHS pullies and not making much difference. There was no underdrive alternator pulley any way. Also I returned them back when the OE ones literally made zero difference. They are still looking through the car trying to find anything abnormal or wrong with it that would cause it to produce less electrical output and over heat as a result. Even today, as soon as they attach cables from another running BMW (in this case the other car was an E46 M3 coupe, bone stock). temps drop in three mins LOL. This is getting to the point where i do not want to drive the car in summers and just drive it in weather under 35c. This would be a damn shame and loss but what to do.

if you increase RPMs do the amps increase?

Voltage regulator on the alternator checked?

I agree measuring voltage at the aux fan is a worthwhile test. I still believe there is a wiring issue somewhere.

https://aa1car.com/library/charging_checks.htm

[0-60motorsports]

Is there an underdrive pulley anywhere on the accessory belt?

No brother. If you read the past posts on this thread i mentioned removing my BHS pullies and not making much difference. There was no underdrive alternator pulley any way. Also I returned them back when the OE ones literally made zero difference. They are still looking through the car trying to find anything abnormal or wrong with it that would cause it to produce less electrical output and over heat as a result. Even today, as soon as they attach cables from another running BMW (in this case the other car was an E46 M3 coupe, bone stock). temps drop in three mins LOL. This is getting to the point where i do not want to drive the car in summers and just drive it in weather under 35c. This would be a damn shame and loss but what to do.

[eacmen]

Well every earth connection disconnected, checked and reinstalled......No luck yet.

The new Valeo alternator that i ordered and removed because it did not make any difference was installed on another E46 M3 a few days back and output was near 100Amps...im at under 50 with the same alternator LOL

Is there an underdrive pulley anywhere on the accessory belt?

[0-60motorsports]

Well every earth connection disconnected, checked and reinstalled......No luck yet.

The new Valeo alternator that i ordered and removed because it did not make any difference was installed on another E46 M3 a few days back and output was near 100Amps...im at under 50 with the same alternator LOL

[0-60motorsports]

I disagree with this "ok voltage not enough amperage" diagnosis. Electricity really doesn't work like that. I think you have proven you don't have an alternator problem by replacing it. But seem intent on it being the alternator somehow.

If the voltage is ok then the alternator is working. Load up the car and measure the current and voltage then. Full blower fan, full lights etc.

The alternator will only produce as much current as needed to power the loads of the car and charge the battery. So you can't just measure current and compare to other cars easily.

Measure the voltage *at the aux fan* if you think that it's not getting enough power. There will be some voltage drop compared to measuring at the alternator but it shouldn't be high. Measure with the fan running of course.

Definitely check engine grounds but ultimately if you're seeing a good charge voltage at the battery then I'd say the charging system is good. At least around 13.8V at the battery.

Copy all

[Shonky]

I disagree with this "ok voltage not enough amperage" diagnosis. Electricity really doesn't work like that. I think you have proven you don't have an alternator problem by replacing it. But seem intent on it being the alternator somehow.

If the voltage is ok then the alternator is working. Load up the car and measure the current and voltage then. Full blower fan, full lights etc.

The alternator will only produce as much current as needed to power the loads of the car and charge the battery. So you can't just measure current and compare to other cars easily.

Measure the voltage *at the aux fan* if you think that it's not getting enough power. There will be some voltage drop compared to measuring at the alternator but it shouldn't be high. Measure with the fan running of course.

Definitely check engine grounds but ultimately if you're seeing a good charge voltage at the battery then I'd say the charging system is good. At least around 13.8V at the battery.

[0-60motorsports]

Bad grounds.

Any thick cable on the car make sure the contact is clean and tight.

Thanks brother. I’ll check and report back

[eacmen]

Well Guys, here we are a 9 months later and we still have the same issue and have not been able to find the cause of the car not generating enough amps or anything close to 80 amps that other E46 m3's are making. My M3 is still making 50% less and the strain is causing the over heating as it can not supply enough electrical power to the aux fan......

Anything else I can check as I have checked as much as I can so far. Problem is electrical and not mechanical.

Bad grounds.

Any thick cable on the car make sure the contact is clean and tight.

[0-60motorsports]

Update 1 Sept:

We might have discovered the cause of the overheating. Message from my tech who has been working on my car for more than 14 years:


“Bro, something unbelievable in your car M3, I told them to keep the car engine running while under the sun, they did yesterday and when about to overheat put the battery jump start cable that connected from another car that the engine is running then it solve the overheating, the possible cause is weak alternator, the voltage is ok possible the amperage is low and due of a/c load the aux fan became not efficient to push more air.”

New valeo alternator ordered from FCPeuro.

Update 17 Sept:

So here’s an updated after installing a new valeo alternator and new original bmw waterpump, the car is running much better the amps have not gone up too much. Before the new alternator it was putting out 40amps and now around 79. I have another m3 here with 11000 miles and puts out above 100 amps.

The car now runs cooler in today’s 44c temps it was running 88c coolant temps so that’s normal
But when you go past half way mark on the blower fan it starts going up in heat back to around 96-98c coolant temps.

Any ideas guys? The only thing I haven’t changed is the ac compressor and I really don’t want to lol.

Update 20 Sept:

Just to rule out the new valeo alternator as faulty we will swap a tested on car alternator from another M3 and see if it still behaves the same. Stay tuned lol.

Well Guys, here we are a 9 months later and we still have the same issue and have not been able to find the cause of the car not generating enough amps or anything close to 80 amps that other E46 m3's are making. My M3 is still making 50% less and the strain is causing the over heating as it can not supply enough electrical power to the aux fan......

Anything else I can check as I have checked as much as I can so far. Problem is electrical and not mechanical.

[0-60motorsports]

Update 1 Sept:

We might have discovered the cause of the overheating. Message from my tech who has been working on my car for more than 14 years:


“Bro, something unbelievable in your car M3, I told them to keep the car engine running while under the sun, they did yesterday and when about to overheat put the battery jump start cable that connected from another car that the engine is running then it solve the overheating, the possible cause is weak alternator, the voltage is ok possible the amperage is low and due of a/c load the aux fan became not efficient to push more air.”

New valeo alternator ordered from FCPeuro.

Update 17 Sept:

So here’s an updated after installing a new valeo alternator and new original bmw waterpump, the car is running much better the amps have not gone up too much. Before the new alternator it was putting out 40amps and now around 79. I have another m3 here with 11000 miles and puts out above 100 amps.

The car now runs cooler in today’s 44c temps it was running 88c coolant temps so that’s normal
But when you go past half way mark on the blower fan it starts going up in heat back to around 96-98c coolant temps.

Any ideas guys? The only thing I haven’t changed is the ac compressor and I really don’t want to lol.

Update 20 Sept:

Just to rule out the new valeo alternator as faulty we will swap a tested on car alternator from another M3 and see if it still behaves the same. Stay tuned lol.

[0-60motorsports]

So here’s an updated after installing a new valeo alternator and new original bmw waterpump, the car is running much better the amps have not gone up too much. Before the new alternator it was putting out 40amps and now around 79. I have another m3 here with 11000 miles and puts out above 100 amps.

The car now runs cooler in today’s 44c temps it was running 88c coolant temps so that’s normal
But when you go past half way mark on the blower fan it starts going up in heat back to around 96-98c coolant temps.

Any ideas guys? The only thing I haven’t changed is the ac compressor and I really don’t want to lol.

[yhp2009]

Are you saying the AC compressor drags and creates a load even when the AC isn't on and the compressor should be freewheeling?

I think he meant that a bad alternator can have a similar effect as a bad compressor

[S14]

Wow a 7 year old battery, got your money out of that one! It makes sense it could be the Alternator causing the overheating issue. It's kinda the same if the AC compressor was going bad causing extra load/drag on the system. Hope this solves the problem.

Are you saying the AC compressor drags and creates a load even when the AC isn't on and the compressor should be freewheeling?

[WOLFN8TR]

My battery wasn’t holding a charge anymore since it was around 7 years old so I replaced it. Once in a while I still get a “low battery” message on my uniden r3 radar detector even with the new battery and the car overheats (on hot days 95+) with the AC on. Wondering if it’s the alternator as well.

Wow a 7 year old battery, got your money out of that one! It makes sense it could be the Alternator causing the overheating issue. It's kinda the same if the AC compressor was going bad causing extra load/drag on the system. Hope this solves the problem.

[0-60motorsports]

Fair enough. Thanks again for keeping us updated and knock on wood for the new idea. If it is the alternator that would be a relief and a head scratcher for sure.

Yes Sir, here to contribute as much as I can and to learn. Alternators on route, should be here in 4 days. In the meantime I’m going to install some purple solid subframe bushings lol