Overheating while running A/C

[0-60motorsports]

Nothing to update, We still have not been able to find the cause of the amperage drain and this is what i suspect caused damage to the previous DME and is causing a slight misfire. When another running car is connected to my car and amps go up to near a 100 the misfire goes away immediately and temps drop as aux fan is getting full electrical juice to run at top speed.

to be honest I have given up and have decided to just the park the car up and thats that......we'll see if or when i ever touch it again. Honestly its just just shit that no one could find the issue from my side.

[0-60motorsports]

Well shutdowns over, back at it lol…. Will update when I have something.

[0-60motorsports]

Guys I appreciate all your advice but Covid and shut down are leading to my hands being tied right now and not able to get your suggestions implemented properly. I’ll post back when I can physically go to the shop and have all the tests done in the right way (some things get lost in translation too). That’ll be in 10-15 days.

[sapote]

if you have 60A running into the battery for extended periods (assuming -ve is charging the battery with your clamp), then something else would seem wrong. That's a lot of energy going into a battery.

Good point, as I also overlooked the 60A measurement at the battery cable. This is not normal for either the current flow out, or into the battery, with engine running. I remember OP even said donor car had close to 100A, at the battery cable too? This can't be true.

[Shonky]

So what should I do? I am only reporting back what they are telling me. Even swapped in a new aux fan and it made zero difference. Covid is not making it easy to get things done or get info especially when we have a shut down in effect right now which will end on the 25th

Well the problem is being a middle man it would seem. You ask for advice here and we give our ideas. However some simple things we suggest don't seem to happen so either your shop is not doing them or the full message is not passed on. I can understand they might not want to listen to the customer.

Seems like your shop just wants to replace parts more than diagnose the actual problem. You say the fan power supply was tested. How was it tested?

You seem convinced it is aux fan related (and there's not even a guarantee of that). Measure the actual power (i.e. voltage and current) to the fan *at the fan* and compare that with and without the donor car connected. This has already been suggested, but you come back with "the aux fan power supply is ok, and we replaced the fan anyway". No one here suggested replacing the fan yet. Or measure the speed as suggested. Do that with and without the donor car/power supply. If the fan speed or its power input changes (and the car cools down), you at least know you're on the right track. Fans are pretty simple things

The current measurement at the battery I'm not sure is even helpful. All that tells you is what is going to or from the battery. I don't know the exact wiring but that would not be supplying any devices at the front of the car. I don't see how your load/no load measurements really reflect the alternator's output. Even then, if you have 60A running into the battery for extended periods (assuming -ve is charging the battery with your clamp), then something else would seem wrong. That's a lot of energy going into a battery.

Without me re-reading the whole thread are you sure your temperature measurement is correct? i.e. there's no chance that something electrical is causing the temperature to read high?

[sapote]

The voltage is at 13.8- 14.1 so the issue is not the charging system, .

Read post #85 , even with 14v charging, the fan could still run slow if .....

[0-60motorsports]

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

Your are still fixated on the amperage for some reason.

So what should I do? I am only reporting back what they are telling me. Even swapped in a new aux fan and it made zero difference. Covid is not making it easy to get things done or get info especially when we have a shut down in effect right now which will end on the 25th

[Shonky]

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

Your are still fixated on the amperage for some reason.

[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.

[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.

[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.

[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

[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.

[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.

[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.