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Hi, I was wondering if anyone could give me some guidance on an issue I've been having for the past couple months. I'll try to give as much info as possible.

Basically, the A/C on my 2001 330i (manual transmission) doesn't work well in high ambient temperatures. I first noticed this after I bought it in early September of last year, but didn't really start considering it until April of this year.

What I've noticed...
- The A/C doesn't blow cold if I start the car up and drive in the middle of a hot day
- If I drive long enough (30-45 mins) the air can sometimes catch up if it's not too hot out.
- The freon seems to be properly charged (At the highest "safe" pressure)
- When parked, I checked the compressor and aux fan and they both ran. The compressor would turn on and off, but did so more frequently until it had cooled down some inside the cabin.
- It doesn't sound like something is wrong (i.e. it's not loud), but I can hear the compressor engage and disengage from inside the cabin

I did some checking around already and I saw someone suggest a bad relay for the aux fan as a possible issue, but then the aux fan does run so I'm not sure what's wrong. Overheated system? Overcharged system? God forbid, bad compressor?
 

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I cannot recall if these systems have a high pressure switch, but I do recall they have a low pressure switch.

If the low side pressure drops too low the compressor will kick out. If the system has a high pressure switch, then this could cause the compressor to kick out as well.

Most AC problems are due to improper charging, as I recall these cars have variable displacement compressors so it is hard to charge/verify charge just by pressures. But pressure extremes can be an indicator of problem.

How do you know the refrigerant charge is correct?
 

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Well compressor will do what's called short cycling if the system is not properly charged. It sounds like you are low and have air in the system which is why the psi is in the safe zone. Psi is not the correct way to measure a coolant systems charge. Psi will change due to temp and humidity and if you are unaware of an air pocket will give a false reading.

Weight is how the system should be charged. There is a sticker under the hood that will give you the correct weight of refrigerant. The only real way to truly help a low charge situation is to have a shop or even some quick lubes hook up a machine. Then they will purge the system, put a pressure test onto it to check for leaks and if all is ok then recharge to the proper weight.

Hope that helps you out.
 

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+1 . If it gets cool after a while the freon(R134) is low. Take it in to a qualified a/c shop. They will purge the system, put a vacuum on the system to test the integrity, clean the condenser, and recharge it. For a few extra bucks they will put in a uv dye to check if (when) it goes out again and see where it's leaking. That service on my Yukon just cost me $140.00.
 

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It is low on freon. Go to a parts store and rent a manifold guage set to read the pressure.

Need actual pressures for low and high side. Record your ambient temperature too.

I just topped my ac in the 330i with a few oz of r134a and she is 26 degree cold coming out of the center vent.


.
 

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E46 F10 W204 W212
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Hi, I was wondering if anyone could give me some guidance on an issue I've been having for the past couple months. I'll try to give as much info as possible.

Basically, the A/C on my 2001 330i (manual transmission) doesn't work well in high ambient temperatures. I first noticed this after I bought it in early September of last year, but didn't really start considering it until April of this year.

What I've noticed...
- The A/C doesn't blow cold if I start the car up and drive in the middle of a hot day
- If I drive long enough (30-45 mins) the air can sometimes catch up if it's not too hot out.
- The freon seems to be properly charged (At the highest "safe" pressure)
- When parked, I checked the compressor and aux fan and they both ran. The compressor would turn on and off, but did so more frequently until it had cooled down some inside the cabin.
- It doesn't sound like something is wrong (i.e. it's not loud), but I can hear the compressor engage and disengage from inside the cabin

I did some checking around already and I saw someone suggest a bad relay for the aux fan as a possible issue, but then the aux fan does run so I'm not sure what's wrong. Overheated system? Overcharged system? God forbid, bad compressor?
Those symptoms sound very familiar. In my case the system was overcharged.
 

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This may seem strange...but what it's your ambient temperature reading on your OBC reading? My car was doing the same whenever the car would read -40 degrees but if it stayed at 122 degrees it would run all the time. Now I've fixed my ambient temp sensor to read correctly and it's never done it again.
 

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This may seem strange...but what it's your ambient temperature reading on your OBC reading? My car was doing the same whenever the car would read -40 degrees but if it stayed at 122 degrees it would run all the time. Now I've fixed my ambient temp sensor to read correctly and it's never done it again.
That's a different issue although the symptoms appear the same. The system won't run below a threshold ambient (below freezing I think) so a reported -40 kills the compressor (by design).
 

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Relationship between IHKA & Electric Fan

A/C REQUEST Range: ON/OFF
This parameter indicates whether or not A/C operation has been requested by the instrument panel control settings. Reads ON when A/C is requested and reads OFF when A/C is not requested. Depending on operating conditions, the ECM may or may not energize the A/C compressor according to the switch request.


FAN Range: 0 to 100%
This parameter indicates the ECM-commanded duty cycle of the engine cooling fan motor, which determines fan speed. The fan speed may be based on the following factors:
Radiator outlet temperature sensor input exceeds a preset temperature
• IHKA signaling via the K and CAN bus based on calculated refrigerant pressures

• Vehicle speed
• Battery voltage level


COMPRESSOR SHUTOFF SIGNAL Range: ON/OFF
The IHKA module monitors the full load input from the ECM. If the ECM detects “full load” conditions, it signals the IHKA control module to disengage the A/C compressor. Some of the conditions for compressor shutoff may be:
• Vehicle speed less than 10 MPH (16 KPH)
• Throttle is wide open
Engine coolant temperature has reached a maximum temperature
The compressor may be turned off for a maximum of 4 minutes (actual duration may differ between systems).


In certain conditions the AC compressor will be shut off in cycles as a safety measure when the engine coolant temperature threshold is exceeded as a result of the electric fan not working or effectively enough to keep the coolant below the threshold - this may happen more frequently at speeds below 10 MPH (16 KPH)
 
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