F30 340i A/.C Problem
Discussion
So the recent hot weather demonstrated that the A/C isn't working properly. I've had the system checked today - no leaks and the amount of coolant is correct. One thing that the guy noticed was that pressure in the system was too high.
He said that it's either the fan control module or a blocked condenser. Does this sound right, and are there any other things that could be causing the problem?
He said that it's either the fan control module or a blocked condenser. Does this sound right, and are there any other things that could be causing the problem?
RUSSELLM said:
Pressure too high is a weird one. I’ve worked on the electrical side of AC, and I’ve watched our mechanics do fills/empties, but I’ve not heard that one before.
Is he plugged into the OBD and reading the pressure sensor output, or using the dials on his fill machine ?
He used the dials on the fill machine. He suggested that because the fan wasn't running at full speed, the coolant wasn't condensing properly leading to the pressure going up and the compressor shutting down.Is he plugged into the OBD and reading the pressure sensor output, or using the dials on his fill machine ?
Monty Python said:
RUSSELLM said:
Pressure too high is a weird one. I’ve worked on the electrical side of AC, and I’ve watched our mechanics do fills/empties, but I’ve not heard that one before.
Is he plugged into the OBD and reading the pressure sensor output, or using the dials on his fill machine ?
He used the dials on the fill machine. He suggested that because the fan wasn't running at full speed, the coolant wasn't condensing properly leading to the pressure going up and the compressor shutting down.Is he plugged into the OBD and reading the pressure sensor output, or using the dials on his fill machine ?
My normal route…
Electrically wise, when you interrogate the HVAC module, you should be able to read the pressure.
A zero figure, will tell me I have a faulty pressure sensor.
A low figure of less than 100, will tell me the system is empty and I’m reading residue air.
A figure over a hundred and less than a 1000 will tell me I’ve got gas in.
When I turn the AC on, I’m expecting that pressure to rise. This is where I find his fault diagnosis a bit weird. That said, I’m not an AC expert
If the pressure doesn’t rise, I’m normally chasing the compressor next. Some are easy to spot when they’re turning, others are a little more tricky.
If I can see nothing wrong with the compressor, I’m back into the HVAC module to make sure I’ve got ‘demand’
Not sure if that’s of any help to you.
The B58 is interesting in that it doesn’t use an air to refrigerant condenser/rad like most other cars. It actually uses a water/refrigerant rad (same circuit as the charge cooler).
The upshot of this is that - your refrigerant level may be fine but there is a common problem whereby the charge cooler circuit radiator gets a leak (it is at the front of the numerous air/water rads in the rad pack) as it is the front most radiator and subject to stone impacts (later BMW added stone guards to stop this). This will mean the AC circuit has no way of getting rid of excess heat so doesn’t work and will trip on high pressure (why you are seeing high pressure). You will also find your car is pulling timing and not putting out as much power as your charge air is also not being cooled.
I would put money on you having a leak in your charge cooler circuit
Edit - I believe BMW refer to the charge cooler circuit as the “low temperature coolant” so I’d check to see if that has any water in it - I believe it is the smaller of the two coolant tanks and closer to the front of the car. Unless I’m mistaken it also doesn’t have a low level warning like the main tank so no dash alerts pop up.
The upshot of this is that - your refrigerant level may be fine but there is a common problem whereby the charge cooler circuit radiator gets a leak (it is at the front of the numerous air/water rads in the rad pack) as it is the front most radiator and subject to stone impacts (later BMW added stone guards to stop this). This will mean the AC circuit has no way of getting rid of excess heat so doesn’t work and will trip on high pressure (why you are seeing high pressure). You will also find your car is pulling timing and not putting out as much power as your charge air is also not being cooled.
I would put money on you having a leak in your charge cooler circuit
Edit - I believe BMW refer to the charge cooler circuit as the “low temperature coolant” so I’d check to see if that has any water in it - I believe it is the smaller of the two coolant tanks and closer to the front of the car. Unless I’m mistaken it also doesn’t have a low level warning like the main tank so no dash alerts pop up.
Edited by a7x88 on Sunday 25th July 10:51
I believe you are supposed to use the same G48 coolant as the engine coolant circuit, but you could probably top up with distilled water and see if it solves your issue. Just remember to get it changed sooner rather than later as it you definately don’t want it to freeze!
Pretty certain you will need a new front low temp cooler radiator though as it will have a leak. Some people have had luck with BMW contributing to this as they clearly recognised it was an issue and later cars had rock guards fitted.
Pretty certain you will need a new front low temp cooler radiator though as it will have a leak. Some people have had luck with BMW contributing to this as they clearly recognised it was an issue and later cars had rock guards fitted.
Monty Python said:
Great - I'll pick some up tomorrow. I don't suppose you know what capacity it is (litres)?
Looks like BMW quote 3.9L.They also seem to make a big deal about only filling the system with a special vacuum filling system.
"Filling without the vacuum filler device (watering can filling) is not permitted.
Non-compliance will result in danger of component damage and/or engine damage.
Filling specification absolutely must be adhered to.
The operation of the vehicle is not permitted unless the filling procedure has been completed. Otherwise, functional limitations (degradation) and/or overheating may occur.
A bleeding procedure is required after a part has been exchanged in the cooling system and/or after refilling the cooling system."
Whatever you do has to be better than running empty though.
Well you seem to have hit the nail on the head - filled the tank up, started the engine and put the A/C on and the coolant started dripping out from the front of the car. I suspect it's been like this since I bought it, as a leak like I've got is quite obvious. Guess I'm going to end up with a large bill to fix it.
I believe it’s around £700 or so to fix from a BMW garage. Do a search on babyBMW (the M140’s are more prominent and have the same issues). People have had luck with BMW paying in entirety or at least parts.
I would look to have rock guards retrofitted or it’s just a matter of time till it happens again
I would look to have rock guards retrofitted or it’s just a matter of time till it happens again
I had this on an F20 125i. Mine missed the rock guards being installed as standard by a month. Car was built in July 19 and came in as standard in August.
If you know your way around a socket set then definitely something that can be done at home. I believe the radiator for the F20 was £280 and a bottle of BMW coolant.
I don't know the F30 specifically but if doing it yourself take both front wheels off as it makes life a lot easier getting to the two bolts holding the front bumper on inside the front wheel well.
If you know your way around a socket set then definitely something that can be done at home. I believe the radiator for the F20 was £280 and a bottle of BMW coolant.
I don't know the F30 specifically but if doing it yourself take both front wheels off as it makes life a lot easier getting to the two bolts holding the front bumper on inside the front wheel well.
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