[Chief Orman]

My A/C runs perfectly 95% of the time. However, in really hot weather it will just stop working...no cooling, no blower. The belts and compressor are fine. The blower motor was changed last year. Almost feels like a wonky thermostat issue. Any ideas?

[Cruiser124]

Originally Posted by Chief Orman

My A/C runs perfectly 95% of the time. However, in really hot weather it will just stop working...no cooling, no blower. The belts and compressor are fine. The blower motor was changed last year. Almost feels like a wonky thermostat issue. Any ideas?

Originally Posted by Chief Orman

My A/C runs perfectly 95% of the time. However, in really hot weather it will just stop working...no cooling, no blower. The belts and compressor are fine. The blower motor was changed last year. Almost feels like a wonky thermostat issue. Any ideas?

How's your battery? Heat can weaken battery output so with hot temps and a weak battery the car may be shutting down connivence functions ie: your climate control system which is why your blower turns off. The ac is probably still working but no fan.

[335dlci]

Thermostat or compressor or amount of freon has nothing to do with fan speed. As mentionee. Battery voltage can cause this.

[kbsilver]

I have also seen situations when the battery is low (such as radiator fans running after shutdown due to regen) that the A/C will not kick in until the car has run a while and the battery charges back up.

Until I recognized the pattern a few times I thought the A/C broke.

[RL18]

Originally Posted by kbsilver

I have also seen situations when the battery is low (such as radiator fans running after shutdown due to regen) that the A/C will not kick in until the car has run a while and the battery charges back up.

Until I recognized the pattern a few times I thought the A/C broke.

Same happened too me in the winter with the heat, wouldn't let me go over the 3rd fan speed until it charged the battery up

[TYS335D]

I've had this happen at least twice, both times while on trips in hot summer weather. The situation corrected itself without any repairs. I am not absolutely certain, but I believe that the issue was caused by the evaporator core freezing up, preventing air from flowing over it to the interior of the car.

The first time, I was prepared to continue my trip after an overnight stop with no A/C. However, I found that it was working perfectly after an overnight stop. The second time, I just turned off the A/C and kept driving. After just a few minutes cold air was flowing and everything returned to normal. This was all in fairly hot, humid weather. I've wondered if anyone else ever had this problem.

[Tonethejackal]

My blower will suddenly lose the higher speeds and seem to drop to low speed even though the dash says the blower is on high. Still seems to blow cold air so I suspect the fan control signal is wonky. Haven't really figured out how to check it yet. Does the same if ac is off.

[kbsilver]

The blower issue sounds like a failed Final Stage Resistor. This was a common issue in previous generation BMWs. Its the device that converts the fan speed signal into actual power to run the fan motor. I've changed them on an E39 and E46. When it goes bad the fan basically has a mind of it's own. Personally I have no idea where it would be located in a newer BMW except to say somewhere under the dash near the blower motor.

[335dlci]

Originally Posted by kbsilver

The blower issue sounds like a failed Final Stage Resistor. This was a common issue in previous generation BMWs. Its the device that converts the fan speed signal into actual power to run the fan motor. I've changed them on an E39 and E46. When it goes bad the fan basically has a mind of it's own. Personally I have no idea where it would be located in a newer BMW except to say somewhere under the dash near the blower motor.

Or most likely related to the recall for these vehicles...

[Tonethejackal]

Resistor has been changed a few times (aftermarket unit and recall repair) so I don't this it is the resistor causing the speed drop. I want to check the signal from the control and I tried with my multimeter across the two pins and go no voltage so I'm wondering if the signal is digital. If so, how can I check it?

[Tonethejackal]

Bump. How can I check to see if I am getting a control signal to the fan resistor a what is the value of the signal?

[Chief Orman]

I started this thread and for the life of me I can't remember how I resolved the issue… I did put in a new fan motor

[skincandy9]

I enjoy fixing the recall myself a new blower unit was installed instantly fixed the no air coming thru the vents and now I have the air blowing through my vents it does not seem to be cold at all times come into the summer car is not much fun to drive it without AC it’s not freezing cold max AC like I remember and dream about

[Chief Orman]

Originally Posted by skincandy9

I enjoy fixing the recall myself a new blower unit was installed instantly fixed the no air coming thru the vents and now I have the air blowing through my vents it does not seem to be cold at all times come into the summer car is not much fun to drive it without AC it’s not freezing cold max AC like I remember and dream about

When the temperature outside gets too high the a/c just dies…WTF….any ideas?

[montr]

Originally Posted by Chief Orman

When the temperature outside gets too high the a/c just dies…WTF….any ideas?

Assuming that your A/C charge level is OK and all sensors are OK, I had cases where A/C stop when it is very hot and humid outside. It is because the fan speed is set too slow, causing the evaporator to freeze.

[Chief Orman]

Originally Posted by montr

Assuming that your A/C charge level is OK and all sensors are OK, I had cases where A/C stop when it is very hot and humid outside. It is because the fan speed is set too slow, causing the evaporator to freeze.

Damn helpful…thank you…how to fix?

[montr]

Originally Posted by Chief Orman

Damn helpful…thank you…how to fix?

Set fan speed higher

[CvilleBill]

This happened to my car about a month after the blower motor wiring recall was done on my car. I installed a new fan and it worked for about a week. Pulled the fan plug and had no voltage. By accident bumped the wires and the fan started running. BMW screwed up the recall on my car. I cut out their fix and its worked fine since.

[Tonethejackal]

Originally Posted by CvilleBill

This happened to my car about a month after the blower motor wiring recall was done on my car. I installed a new fan and it worked for about a week. Pulled the fan plug and had no voltage. By accident bumped the wires and the fan started running. BMW screwed up the recall on my car. I cut out their fix and its worked fine since.

I gonna have to try the "jiggle the wires" test next time my fan decides to switch to low on me. Might have to tie a string to the bmw repair splice to yank on when it goes out while I'm driving.

[robnitro]

It's the battery management system that puts climate control into low power mode.
If you put the defroster on it'll go at full blast.

You can put it on a charger for a couple of hours and the ibs system will no longer see the battery as depleted. Sadly, driving alone takes a long time to get the battery up to snuff in the heat because in warm temperatures it'll stick to 13.8v to preserve battery life, even if IBS knows the battery is low.
It's a crappy system with a lot of assumptions and bad presets.

There's a coding where you can disable this "feature"... I also disabled the heater recirculation pump, since mine was groaning and I really didn't need it even in cold weather, idle heat was fine.

I'll try to find the coding when I'm home in a few days, it's saved on my laptop.

[awenthol]

Originally Posted by montr

Set fan speed higher

+ turn a/c off... Have had this happen to me twice now, on long road trips (6+hrs, not shutting the car off).