Problem with A/C
 

I have a BMW e53 3.0d 160kw and I have the following problem with A / C: When I press the A / C button it will not start the air conditioning compressor and fan when the engine is not at 90 degrees (at operating temperature) and until I give more gas once (over 3000 rpm ). Here is the reading from the inpa:
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You have to determine is the AC clutch not engaging or do you have variable displacement compressor and it's stuck at low/no compression until you go to 3000.

Once it kicks on will it operate properly until key off?

Once it starts and works until I turn off the car and it cools down a bit. example: the air conditioning works and I turn off the engine for 5 minutes and start again and it still works without problems because the engine has not cooled down


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but if it stays off for about 15 minutes or more then it won't work and I have to repeat the above (gas over 3000rpm and the engine has to be hot)


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Does INPA show any errors in the IHKA unit?

One error


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Don't keep us in suspense. What's the error?

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Aux heater disconnection?

Can you monitor the compressor status? To confirm if the compressor clutch is being engaged when you press the snowflake?

No, what could be the problem with it, the heater maybe?

When I get home I'll try to find it all in INPA


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I have a picture I took last time I sent it to you, when I press the button, Inpa prints that the compressor is on but there is no cold airhttps://uploads.tapatalk-cdn.com/202...721cd70e36.jpg


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Mine has the same problem. Until the engine is at temp, it won't cool. The fan doesn't turn on when it's cold. The fan works when manually tested using a Foxwell Pro. If it's hot outside, I get moving quickly so speed cools the condenser. Once it's hot, the fan is on cooling the engine keeps the A/C ice cold. Mine has no codes either.

Have you tried changing any of the parts so far (that I don’t try if it’s not up to it)?


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Start your engine...go to the radiator output temperature sensor (on the lower radiator hose) and then disconnect the connector. The fan should start right up. If not, replace the sensor. If it does start right up, then do the same test with the AC pressure sensor.

When i dissconect pressure switch fan work. i will check radiator sensor


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As far as I can see on the internet, my sensor is near the intake manifold? on the lower hose of the radiator is not


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Problem with A/C
 

Pressure sensor 0.9v. It's pretty low on the scale, what does that read when temp is hot and AC runs?

I don't know what the normal voltage off the press sensor is. It's not a simple on/off switch it sends a voltage to the brain that figure out the actual pressure. If it reads low incorrectly, it may allow operation as ambient temperature raises the pressure inside so see what is the voltage on the pressure sensor when it works and maybe watch real-time the ECT as well to see the exact temp where it magically starts working.

Yeah... I'd want to throw a set of gauges on the AC system. I like the theory that it could be right on the edge of too low for the system to kick on when cold, but that higher temperatures kick it over the threshold.

Note: Do NOT just add refrigerant to the system willy-nilly.

1.5V when ac work. What is etc
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10 days ago when I sent you pictures the voltage was 1.2V and it didn't work. now i don't know if this is a coincidence or it's really too low voltage


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Checked my notes from when I was debugging my aux fan (turned out that was the one and only problem, so my AC, pressure sensor, ECU, etc. were all good for this data):

2001 3.0i

"AC Pressure sensor - in AC line very close to the lower radiator hose. Measured in Foxwell:
Ignition ON, engine stopped, AC off, cold: 1.25V
... connector removed: 5.00V
Engine running: 1.24V
Engine running, AC on: 1.76V, rising
... connector removed: 5.00V"

Now I started the engine and the air conditioning no longer works, the voltage is 1.2V, then I gave the gas twice to about 3000rpm and it worked and the voltage is

The fan does not start up when I pull the sensor off the coolant line. So I guess my sensor is toast. Time to drain the coolant and replace it. :(

Now it behaves differently (maybe because it's colder outside) Basically, the air conditioning voltage is 1.8V and I turned off the air conditioning on the button the voltage drops to 1.2V. I press the button again to turn on the air conditioning, the voltage remains 1.2V and does not work, then I give the gas up to 2500-3000rpm once and the voltage goes to 1.8V and the air conditioning starts working


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It would appear the sensor is working and sees enough pressure. You need to confirm if the clutch is engaging when you press the snowflake. Symptoms suggest the clutch is not grabbing

How, to listen just under the hood or?


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You can see the compressor from top side. Have someone push the A/C button on and off. You should hear it click. Plus notice RPMs change. On other vehicles the clutch will engage with the engine off. I'm not sure about BMWs.

Watch the clutch while somebody presses the snowflake. Take a slomo video even better.

It can be tricky to see the inner part spin since the outer pulley off course always spinning.

Also: in software you should be able to read status of the clutch.

I suspect the clutch air gap is off and not grabbing or variable displacement compressor is stuck at zero displacement until you rev.

You need to figure out if the clutch is grabbing

Problem with A/C
 

The clutch catches when I turn on the snowflake
Aux fan not work
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That's backwards. Pulling the pressure sensor from AC line will make the aux fan spin; indication of a problem with the fan not the AC.

Can you engage the fan with your scanner?

You said coolant line, do you mean refrigerant line? Pulling the radiator outlet line I'm not aware of having an effect on that

I was able to turn on the fan with the diagnostics


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Yes, I can manually activate the fan. Plus it takes 10+ seconds to spin down after turning it off when hot. I've not pull the refrigerant sensor off. Unlike others, it has to be emptied of R134. Luckily, I have the tools to do a R134 vac and fill.

Try disconnecting the pressure sensor on the air conditioning pipe, you don't have to remove the sensor


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Hey so I experienced this problem and found the issue searching other forums. I'll see if I can find those links, but bear with me.

BMW AC compressors of this era have a mechanical valve inside that can fail, and make diagnosing the problem impossible. The compressor clutch will turn on, but the AC will blow warm until you rev the engine. Because the system thinks the AC is working, you'll see a bunch of electrical anomalies since the pressures aren't what the system expects.

So if your problem is that the clutch is engaging, but you don't have cold air until/unless you rev the engine OR it takes a long time to cool off, this valve inside the compressor is bad and the compressor needs to be replaced.

Diagnosis of this problem is almost impossible since it's a physical valve inside the compressor so no error of this problem will show up in the scanner.

I'll see if I can find a link to the thread that explains this better. But long story short you need a new compressor.

It is not possible to replace the valve itself but the whole compressor has to?


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So look up "variable stage compressor" that's what is in these cars.

No, when that goes bad the compressor needs to be replaced.

It took me a LONG time to track this down because this problem is really common and most forum suggestions are to do a ton of diagnosis. I wish I had saved the thread.

But if your problem is as I described (AC blowing warm but system is full and cools of when driving or revving the engine) then the variable valve is bad and the compressor is definitely the problem.

My problem is this: The compressor and fan will not start until the engine reaches operating temperature and I do not give gas up to approximately 3000rpm once. And then everything works normally while the car is standing and driving


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Same problem. I found the post and it was on this forum. It even describes your issue where the fan doesn't come on.

A bad valve will cause these problems as well. You can see the post here (post 6). Replace your compressor.

https://xoutpost.com/bmw-sav-forums/...tml#post879005

That could really be a problem, but I see on the internet that only that valve can be bought, I don't know if anyone did that here


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Aux fan doesn't always run from AC on. Temp dependent.

Disconnecting the freon pressure sensor should spin the aux fan.

When my AC wouldn't work I had to replace my aux fan. I was able to get AC to work by manually engaging the compressor with my foxwell.

Can you see the inner part of compressor clutch turning? The two main possibilities are:

➀ clutch air gap too much and not engaging. (Click yes, spin no)

➁ variable displacement compressor stuck at zero.

Since revving makes a difference, I think it's 2. You get higher pressure than me once it kicks on.

Given that you have to do all the exact same work to replace the valve, why not just put a brand new compressor in there? It seems like a penny wise / pound foolish decision.

You have to evacuate the system, remove the compressor, clear the lines, clean, etc. It would take more time than just putting a new compressor back in, which at the age/mileage of our cars they probably are due anyway.

But totally your call. Regardless, this is the problem AFAIK.

BTW this is not just me speculating. I had a very similar problem, when through the diagnosis, found that thread and replaced the compressor and everything worked again.

To rotate the inner part, I will have to change the valve of the variable compressor or I will take a new compressor


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Because the price of a compressor is much higher than the price of a valve (a compressor would say it’s good because it cools like crazy). But it is possible that I will buy everything together. Thanks a lot.


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Just trying to add some accuracy here, copying from my notes back when debugging my failed aux fan on my 2001 3.0i (same fan on all gas-engined E53s) ...

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Pulling the connector off the coolant temp sensor on the lower radiator hose will not turn the fan on. As detailed below, the ECU considers that to be a temp of -54*F, so not hot at all, so no need for the fan.

This has nothing to do with the temp gauge in the instrument panel. No warnings result when the temp varies to extremes.

Tests done with ignition ON, engine not running, battery charger maintaining voltage.

I used the foxwell to monitor live data on that temperature. Measured about 71F (ambient temp) when starting.

Disconnected the connector, simulating infinite resistance ==> -54*F

Measured resistance of the sender = 2.8 kOhms

Put the following resistors across the connector to simulate different temperatures:
temp [F] resistance [kOhms]
-54 infinity (unplugged)
71 2.8 (actual sensor)
94 1.48
122 0.80
159 0.40
213 0.151
241 0.100

These were done to confirm how I could simulate an overheated radiator hose, to hopefully trigger the fan to turn. Interweb lore says that you can just unplug the sensor, but that does not seem to work, which makes sense.

The 100 Ohm resistor simulates 241F, and successfully triggers the fan to come on (the command comes [command voltage signal drops], even though the fan did not spin while I was doing these tests - because my fan was broken).

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Pulling the connector off the AC pressure sensor, nearby, while the AC is turned on and the engine running, the aux fan should spin. More specifically as I tested it on my car:

(AC pressure sensor voltages given in an earlier post in this thread)

When the AC was turned on, the fan control signal dropped from its normal (fan off) state of 14V to 12 .. 11V, as before.

When the AC pressure sensor connector was removed, it very quickly ramped down, at about one Volt per second, ending at about 2.0V, which should be almost top speed for the fan.

Corvette is right.
Even though the valve is the problem; it’s more than that -
It’s the design of the variable displacement compressor that leads to this issue, that pressure must increase ( by you increasing rpm’s to 3000) ; that even if you replace the valve with a brand new one , the issue may still be there - due to wear surrounding the valve or other unknown issues ;

That’s why it’d make sense to replace compressor with a conventional type , rather than another variable displacement, because even a brand new one problem may still be there , or return after a relatively short time as tolerances possibly grow requiring your 3000 rpm fix to get the compressor to actually kick in - once it’s working- it’ll stay working-
until the next day when it’s cooled down, and retracts and you’ve gotta go through it all again…-

Are you sure about what you're saying? Do you think that the problem could continue after the valve is replaced?


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Am I certain?

Nope I could be wrong.

You may be lucky and replacing just valve fixes everything;
or maybe you only need to rev to 2000rpms , or your 15 year old compressor lasts another year or two with the fix …

The more expensive V8 models just use a conventional compressor…

Wouldn’t it be nice to just turn the key and get ice cold air almost immediately while it’s idling at only 600rpm?

I’m merely giving you a heads up …

Are you really willing to bet all that time to try and change a valve in a 15 year old compressor vs. putting in a brand new one that will likely outlast the car and work perfectly?

I understand there are cost considerations but I can't see any benefit to even trying this.

Regarding converting to a conventional compressor - my understanding is that making that change requires other changes to the system (I can't seem to recall which ones) but it wasn't as straightforward as just changing it out like-for-like.

I just kept it simple - my original compressor went 16 years and 160K miles before it started acting up. It was no more $$ to put the variable rate one back in, and it will likely never need to be changed again and it worked great for a long time, so the effort to swap didn't really seem to be worth it.

Nothing, it is best to replace it with a new one and then I am sure it will work properly. Thank you for the tips a lot


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Notwithstanding that there is a high likelihood that it's the compressor... OP, have you put a set of gauges on and *confirmed* that you have a proper fill?

Yes, I checked several times and it was loaded properly (440g). It's just weird to me: When I just charge the air conditioner while the connections on the air conditioning pipe are still connected and turn on the air conditioner, the compressor immediately starts working and the fan starts. So it is about the fact that while the air conditioning is being charged and the air conditioning charging machine is displayed on the screen that the charging is over, the air conditioning starts working without giving gas (over 2000rpm) and the next shutdown of the vehicle continues the same


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I have seen often that older cars need more than the spec of grams of R134a. Do you recall the high/low psi when it was working?

That said, symptoms are off failed variable compressor

When the compressor is running low and high pressure are as they should be on the correct compressor, this is what the mechanic told me. And he told me he suspected the valve


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Does anyone know where the FM singal amplifier is located or what could be the problem? I have radio interference, it works a little well and sometimes there is a lot of noise


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I have one connector that is not plugged into the rear window
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Backup camera? Also how's that connected to "problem with AC"

Not to open a new topic all the time, I wrote here. Do you think the e53 has preparation for the rear camera?what could be the cause of the noise on the radio?


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You should start a new topic for any different problem. Illogical combining causes problems to solve any additional issue.

The FM uses wires in back and back left window for antenna. I don't think that's the connector for it I think that wire goes though a side connector but that's a guess.

AND close off this A/C thread with the fix.