A/C causes higher oil temperature gauge reading

[ac427]

I usually drive with the air conditioning on full time.

Recently i noticed that the oil temperature gauge needle was almost vertical during normal driving. Which is about 100⁰C or 212⁰F.

It's never usually that high and hasn't been in 14 years of ownership.

Another symptom occurs when slowing for stopped traffic. You can hear the engine struggle slightly to maintain idle as you come to a standstill.

If i turn off the A/C, the oil temperature gauge shows a much happier 85ish degrees, at long way off vertical anyway.


So, it seems the A/C clutch is fine but there is mechanical resistance in the A/C system somewhere.

What are your thoughts guys?

[dukeofchen]

My car also does this and I haven't resolved it yet, it was most noticeable last year when we had 100+ days in socal, some with more humidity than usual.

The condenser is beat to shit so I was thinking of replacing that, the radiator, and fan clutch in one go (they might all be original) with a proper refrigerant recharge at a shop. My guess is that the inefficient heat dissipation / airflow at the condenser with so many bent fins + corrosion is compounding the issue at the radiator.

[ac427]

My car also does this and I haven't resolved it yet, it was most noticeable last year when we had 100+ days in socal, some with more humidity than usual.

The condenser is beat to shit so I was thinking of replacing that, the radiator, and fan clutch in one go (they might all be original) with a proper refrigerant recharge at a shop. My guess is that the inefficient heat dissipation / airflow at the condenser with so many bent fins + corrosion is compounding the issue at the radiator.

Sounds good but this has been a sudden change rather than a gradual one.

if turning off the AC fixes it, the AC system must be at fault or at least applying a much higher mechanical load to the engine than it should,

Perhaps it would be best to get the shop to test your AC system beforehand?

[Estoril]

How old is your radiator?

[Kevin2772]

I used to have this problem. Replaced my entire fan unit and havent had the issue since. Replaced my oil temp/level sensor as well this last winter and now my oil temp guage rarely makes it to straight up.

[sapote]

but this has been a sudden change rather than a gradual one.

Do you hear the loud efan running high speed with AC on?
I think the old fan lost its horse power.

[dukeofchen]

Sounds good but this has been a sudden change rather than a gradual one.

if turning off the AC fixes it, the AC system must be at fault or at least applying a much higher mechanical load to the engine than it should,

Perhaps it would be best to get the shop to test your AC system beforehand?

When the AC is on the condenser is pre-heating air before it reaches the radiator, vs. when it's off the radiator is more or less getting air at ambient temps.

So I figure an inefficient condenser + radiator of unknown age means that when ambient goes to 90+ the temperature delta is too small for my system's cooling capacity in its current condition. In my case the condenser fins are so beat up that they flaked off when I took a stab at bending them back, so I imagine at the very least that replacing it might get me a couple degrees of extra cooling at the vents.

[ac427]

Thanks all. The radiator and all the Aircon components are probably 20 years old with the exception of the belts and the drier.

Am i right in thinking i can buy a new fan for an E46 non-M3 model and swap the motor in the frame?

Who is the OEM manufacturer for the radiator?

[sapote]

Am i right in thinking i can buy a new fan for an E46 non-M3 model and swap the motor in the frame?

The fan is a DC brush motor, so maybe just replace the worn down brushes. But before doing anything on the fan, you should use inpa to command the fan speed test to check its max speed is valid or not.

[ac427]

The fan is a DC brush motor, so maybe just replace the worn down brushes. But before doing anything on the fan, you should use inpa to command the fan speed test to check its max speed is valid or not.

Do you know where that option is in Inpa?

[sapote]

Do you know where that option is in Inpa?

AI Overview


+8
To test the E46's electric radiator fan using INPA, navigate to Control Unit Drive -> DME (or similar engine control unit) -> Active Tests -> Component Activation -> Electric Fan. This will allow you to activate the fan at different speeds or test its functionality by sending signals from the DME.

[ac427]

Is it possible to clean between the condenser and coolant radiator without discharging the AC system or draining the coolant?

[sapote]

Is it possible to clean between the condenser and coolant radiator without discharging the AC system or draining the coolant?

What do you see between them? Most debris caught by the front condenser. You can use pressure water hose shooting through the fins from the engine side to clean the dust off.

Did the fan run strong at 100% inpa control command?

[ac427]

What do you see between them? Most debris caught by the front condenser. You can use pressure water hose shooting through the fins from the engine side to clean the dust off.

Did the fan run strong at 100% inpa control command?

Thanks, it sounds like it would be better to pressure wash from the back once I ordered a new condenser, which arrived today. Sadly, it had a few bent cooling fins. It is probably was ok but if you buy something new you expect it to be mint.

Anyway, i was impressed by the size of it. I thought it was only going to be a foot square but it's massive.

I haven't had a chance to yest with INPA but i do remember doing it with DIS a month or ago. It's been raining all but I'll have a go tomorrow.

[sapote]

I ordered a new condenser, which arrived today. Sadly, it had a few bent cooling fins. It is probably was ok but if you buy something new you expect it to be mint.

Wondering why do you need a new condenser as the old one seems to be working. Shipping/handling will make some dents on the new item, especially the soft cooling fins. You can straight them out easily with tweezer if you want 100% efficiency, but they will be bent by flying rocks later.