Overheating while running A/C

[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

[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]

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

[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

[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]

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]

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]

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

The tech will keep on checking. I’ll report back with more info on your question once I can go to the shop tomorrow after work.

Voltage regulator was swapped out for a new one.

[Shonky]

I still think you want it to be the alternator and I don't think it is. Hooking up another running vehicle tends to suggest it is electrical though. And I'd stop fixating on the current readings. Current is essentially a function of voltage. If the voltage is there, the current will flow (and thus so will the power) all things else being equal.

If you really want to measure the current of something, measure the current of the auxiliary fan on it's own and compare it against another car with the fans running full.

There seems to be some easy troubleshooting being skipped jumping to things like replacing alternators and regulators.

Where was the "donor" vehicle connected? If it was at the normal jump points, remember that's not the same as at the alternator. Did the fan run faster/sound louder with the donor vehicle attached?

I'd measure voltages at the battery with and without the donor vehicle, and at the fan too. The latter is by far the most critical point since I don't think much else could affect the cooling system so significantly other than the aux fan. The aux fan runs off a dedicated 50A fuse, so can draw a lot of current which can cause significant voltage drop through bad connections.

Alternatively, you could connect the aux fan to an external supply like a well charged battery and see what happens, but really the voltage measurement at the fan will tell you the most IMO.

[sapote]

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

Nobody can control the alternator current or amperage but the load -- heavy load --> higher current, less load --> less current, assuming the alternator output is nominal around 14v. Here what I think:

1) Your AUX fan is not spinning fast enough due to a higher resistance on the supply wires. The tech could use a strobe light to check its speed and compare to a normal car.
* measure the resistance between the fan 2 wires, and compare to the normal car fan. If more than 30% higher then the fan is not good (brushes or commutator issue).
* under the same testing condition (hot ambient and car starts overheating), measure the voltage between 2 fan wires (if it is PWM signal then record the peak voltage of the square-wave signal, should be close to 14v); compare to normal car. If the measured voltage is significantly lower, then this is the root cause: either bad connection on the high side (14v ) or the lower side (to ground).

If this fan is new, then the fan driver could be the suspect.

As about the pressure increased in the A/C high side and low side, this is normal as the gas/liquid in the condenser had unusual higher temperature (due to low fan speed ). If this pressure is high enough the A/C will be shut down.

[0-60motorsports]

Shonky sapote Thank you for your insight and I will pass it on to the techs.....I'll keep you guys updated. Mean time here is the read out with and without load.

Without load



With Load

[Kevin2772]

Just experienced this problem for the first time this weekend. Driving on a really hot day, in traffic. Temp guage started to head to the right. Turned off the A/C and the temp went right back to straight up. Curious where all this will go for you. Mine is a vert so i dont usually use the A/C, but still an annoying problem to have.

[eacmen]

Just experienced this problem for the first time this weekend. Driving on a really hot day, in traffic. Temp guage started to head to the right. Turned off the A/C and the temp went right back to straight up. Curious where all this will go for you. Mine is a vert so i dont usually use the A/C, but still an annoying problem to have.

Overheating while driving is a different issue than overheating at idle. The op’s issue is the pusher fan isnt generating enough airflow at idle.

Overheating while driving is generally a different issue than the aux fan.

[0-60motorsports]

The voltage is at 13.8- 14.1 so the issue is not the charging system, it’s when the car is under load that it’s not putting out enough amps. Checked the power supply to the six fan and it’s good. Investigation keeps going on.

[Shonky]

How is the aux fan supply good? What did you measure and how?

Your are still fixated on the amperage for some reason.