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Discussion Starter #1
Hi Guys, i'm new to posting. so be gentle. :D

i have a 06 530I blowing warm air and it just hit 100+ degrees in the car today in Florida. i grew up in Ireland so if i don't fix it soon im going to rent it out as a mobile sauna.
I have a bit of a time crunch thats why i'm bringing in the big guns.

I have previously read all the A/C threads I could find, and 2 trees from the amazon to print them out. But I need an A/C Wizard to help with Diagnostic.

I'm not sure how to check the sensors and the compressor or in what order.

Here is some Specifics

Trouble code: 9c54 IHKA: AUC Sensor
(I will post more codes later but i have to switch to windows to read them from scanner)

System has pressure, high low & high side pressure
the aux fan behind the radiator does not run when the AC is on
Max AC comes on and blows warm air randomly when it feels like it.
It does not get cold even at high speed.
When I press the snowflake button to turn on/off the AC unit, engine RPMs change

All inside settings set for cold
high amp fuse to the compressor & the low amp fuse from the dash are good.

i have Bentley Manual, and probably every document posted on the internet, I'm dizzy reading.
I have INPA, Rheingold and the Schwaben Professional Scan Tool For BMWs.
I have A/C gauges, A big drum of Freon, and all the tools required to turn it into a tank, a-team style.
I even have a 2008 528i to interchange parts if they are compatible.

But what i don't have is a solid answer to what components to start with or the proper procedure to check the a/c compressor.

I've read the HVAC Control Module sends a signal to the AC Clutch when told to do so & the pressure switch is connected in series, this means too low or too high pressure of R134a will not allow the compressor to engage. But i'm not sure how to check the sensors,


I did the rocker cover gasket, but i think it was leaking oil onto the compressor.
it was sitting a while and had a bunch of leaves in and around the filters at the bulk head under the hood.
it also had the water pump replaced, before I got it.
I reconditioned the Valvebody, mechatronics etc so its been up and down like a $5 hookers knickers on New Years Eve.

I would be eternally grateful if someone could help me get a little cold air blowing on this pasty white Irishmans head in the not too distant future, I seen a pitbull licking his lips outside publix today and i'm fairly sure he was thinking just another 5 mins and this ****er will be cooked just how i like em. Thanks in advance.
 

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BMW CCA 69606
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2,167 Posts
Ignore the AUC code. It controls auto recirc and has nothing to do with AC operation.
Connect gages and report high & low side pressures at idle and 2000 rpm.
If you can reach the low pressure hose on the compressor, it should be cold and should be sweating if humidity is high.
 

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2006 530xi 6 MT
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+1 on don't pay attention to the AUC sensor. That's AUC sensor can activate activate recirculation mode under certain conditions -- for example, if it detects a lot of diesel exhaust.

My 2006 530xi A/C quit blowing cold last summer. I've had the car since new and this was the first problem with the A/C. I bought a set of A/C gauges and hooked them up. Spent a lot of time reading and looking at videos. The proper way is to evacuate and recharge, since you know exactly how much refrigerant is going back in. But, most of us don't have an evacuation machine. Just using gauges alone you cannot tell how much refrigerant is in the system, but you can feel your way. It is complicated and not precise. The ambient temperature also plays a role in what you will see in terms of pressures.

Also found this on newtis: https://www.newtis.info/tisv2/a/en/...tioning/64-50-air-conditioning-check/ASsoB7Z4

Based on that newtis info, a car that is 4-5 years old, BMW assumes can have lost up to 150g (5.3 oz) of refrigerant and not be "broken". I put in half a 12 oz can of R134a and that definitely improved things, but the gauge pressures still seemed on the lower side. It was 90 degrees out when I did it last summer. I ended up putting in an entire 12 oz can of R134a, although there is some that escapes when you connect and disconnect the hoses. I also failed to let the high side hose, *after* being disconnected from the car, to get sucked back into the low side. That's a smaller point, but there is really a lot to know to do good A/C work. I also added oil as noted in the newtis document. Had to buy a special too to add the oil and then the oil also - don't get the wrong oil. If you buy R134a, make sure you get stuff that has no stop-leak additives. Those may cause other problems in the system.

Having done this, I'd say unless you are really interested in learning about this, you might want to just take it to a shop that has A/C equipment. I know many have used the inexpensive refill cans with attached low pressure gauge, but I wasn't really satisfied with that and also wanted the tools I'd need to someday do the entire system. I look periodically for a vacuum pump on craigslist and I'll pick one up one day if it is close by and not too expensive.
 

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Discussion Starter #4
Ignore the AUC code. It controls auto recirc and has nothing to do with AC operation.

ok thank you.

Connect gages and report high & low side pressures at idle and 2000 rpm.

Pressures Before starting

High side 110
low side 96

1.jpg

After starting the car - At idle with air con on, pressure setting are

High side 110
low side 107

no real change on pressures at 2000rpm

2.jpg

Turned off the car and let it sit for 5 mins.

pressure is climbing
High Side 115
Low Side 109

3.jpg

Aux Fan never engaged.

If you can reach the low pressure hose on the compressor, it should be cold and should be sweating if humidity is high.
The only thing sweating is me. low pressure hose on the compressor is warm.
 

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BMW CCA 69606
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Your compressor is not pumping at all.
Low side should be ~30, high side should be 200-300.
Is green led on AC button lit?
 

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2006 530xi 6 MT
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Just asking a set up question....for those readings, I assume you have both knobs on the gauge manifold fully closed.

Before I added any R134a, and my car wouldn't cool, the static, non-engine running pressures were about 82 on both sides.
Started the engine and I would cycle between 8 low /100 high to 20 low /145 high.

Added some R134a, the running engine readings were like 32 low / 195 high. The low side would move only a couple psi as the compressor cycled.
The static, non-engine running pressures were just shy of 100 on both sides.

I think it was like 90 degrees out the day I did this.
 

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There is more than enough pressure to operate the system so don't worry about adding any refrigerant at this time. Chances are you have a faulty refrigerant control valve that is located inside of the ac compressor. Does your outside temp register the correct temperature?
 

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Discussion Starter #8
+1 on don't pay attention to the AUC sensor. That's AUC sensor can activate activate recirculation mode under certain conditions -- for example, if it detects a lot of diesel exhaust.

My 2006 530xi A/C quit blowing cold last summer. I've had the car since new and this was the first problem with the A/C. I bought a set of A/C gauges and hooked them up. Spent a lot of time reading and looking at videos. The proper way is to evacuate and recharge, since you know exactly how much refrigerant is going back in. But, most of us don't have an evacuation machine. Just using gauges alone you cannot tell how much refrigerant is in the system, but you can feel your way. It is complicated and not precise. The ambient temperature also plays a role in what you will see in terms of pressures.

Also found this on newtis: https://www.newtis.info/tisv2/a/en/...tioning/64-50-air-conditioning-check/ASsoB7Z4

Based on that newtis info, a car that is 4-5 years old, BMW assumes can have lost up to 150g (5.3 oz) of refrigerant and not be "broken". I put in half a 12 oz can of R134a and that definitely improved things, but the gauge pressures still seemed on the lower side. It was 90 degrees out when I did it last summer. I ended up putting in an entire 12 oz can of R134a, although there is some that escapes when you connect and disconnect the hoses. I also failed to let the high side hose, *after* being disconnected from the car, to get sucked back into the low side. That's a smaller point, but there is really a lot to know to do good A/C work. I also added oil as noted in the newtis document. Had to buy a special too to add the oil and then the oil also - don't get the wrong oil. If you buy R134a, make sure you get stuff that has no stop-leak additives. Those may cause other problems in the system.

Having done this, I'd say unless you are really interested in learning about this, you might want to just take it to a shop that has A/C equipment. I know many have used the inexpensive refill cans with attached low pressure gauge, but I wasn't really satisfied with that and also wanted the tools I'd need to someday do the entire system. I look periodically for a vacuum pump on craigslist and I'll pick one up one day if it is close by and not too expensive.
Really appreciate the information, I have all the tools and Autozone rents vacuum pump. It looks like the compressor. I was just hoping for someone to say put your left leg in and your right ball out, kick the front bumper and it will be grand. So I didn't have to rip it apart.

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Discussion Starter #10
There is more than enough pressure to operate the system so don't worry about adding any refrigerant at this time. Chances are you have a faulty refrigerant control valve that is located inside of the ac compressor. Does your outside temp register the correct temperature?
Thanks. Is there any way to check the valve before taking compressor out.

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Discussion Starter #12 (Edited)
A/C Pro Needed - 06 530i E60 AC Blowing Warm Air & misery. i have scan tools

Some of the codes itâ€s throwing out of code reader.



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Discussion Starter #13
Just asking a set up question....for those readings, I assume you have both knobs on the gauge manifold fully closed.

Before I added any R134a, and my car wouldn't cool, the static, non-engine running pressures were about 82 on both sides.
Started the engine and I would cycle between 8 low /100 high to 20 low /145 high.

Added some R134a, the running engine readings were like 32 low / 195 high. The low side would move only a couple psi as the compressor cycled.
The static, non-engine running pressures were just shy of 100 on both sides.

I think it was like 90 degrees out the day I did this.
Neither of them do anything other then go up, the last Redding was 115 low and 125 high. Compressor Pull out time I think.

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Thanks. Is there any way to check the valve before taking compressor out.

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One of the wires going to the valve should be grounded all the time, the other wire will have a PWM voltage signal that will vary depending on how much output the compressor needs to achieve. The only thing important here is that the PWM signal changes, this indicates that the ac module is commanding the valve, from there you could check amp draw of the valve to make sure that it is actually working and if it is then chances are the compressor is toast. Of course most of this is a little bit more than the average DIYer is capable of doing.
 

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Discussion Starter #15
(null)
Appreciate the info, been pulling spanners since age 8. I was a full-time mechanic, from age 15 through 21. Motorcycles, boats, cars, then heavy plant machinery. In Ireland we learned by doing.


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One of the wires going to the valve should be grounded all the time, the other wire will have a PWM voltage signal that will vary depending on how much output the compressor needs to achieve. The only thing important here is that the PWM signal changes, this indicates that the ac module is commanding the valve, from there you could check amp draw of the valve to make sure that it is actually working and if it is then chances are the compressor is toast. Of course most of this is a little bit more than the average DIYer is capable of doing.
I found a 04 donor 530i from what I can tell compressor is the same. I'm heading in the morning to get the AC compressor, while I'm there what other parts would be a good idea to get. I was to tear it apart once and make sure it can be fixed in a few days. I'd prefer to bring home a bag of parts and have them spare then to have to go back.

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Again, I'm not an A/C expert....

I think you need to put in a new drier.
Maybe just me, but if I'm going to the trouble of cracking open the system, I'd change all the o-rings with new (at least the ones I could get to without too much trouble). The originals are hard by now.
Same for the Schrader valves cores.
You need some compressor oil. I used PAG 46 that had no magic additives from my local Advance Auto Parts.
 

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2008 535xi wagon
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When I changed just the schraeders I still ended up leaking at the valves. BMW sells the whole valve assembly that threads on, buy these, they're not expensive. All high side o rings are easy enough to replace.

Filter/drier you should replace if the system is exposed to the atmosphere, especially if you don't have any nitrogen to purge the system before reassembly.

But it doesn't sound like you're leaking refrigerant. Your compressor is working at 89% and you're getting a very small pressure differential. Something's blocking flow. A seized compressor, maybe.

You also need an IBS. Unrelated to the issue at hand, but most of your codes point to its absense.
 

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When I changed just the schraeders I still ended up leaking at the valves. BMW sells the whole valve assembly that threads on, buy these, they're not expensive. All high side o rings are easy enough to replace.

Filter/drier you should replace if the system is exposed to the atmosphere, especially if you don't have any nitrogen to purge the system before reassembly.

But it doesn't sound like you're leaking refrigerant. Your compressor is working at 89% and you're getting a very small pressure differential. Something's blocking flow. A seized compressor, maybe.

You also need an IBS. Unrelated to the issue at hand, but most of your codes point to its absense.
Just because the system is opened does not mean the drier needs to be changed. If proper procedures are followed and the system is vacuumed correctly after the repairs are done then drier replacement is not necessary. Also the compressor is not functioning at 89%, refrigerant capacity is at 89%. It's clear to see by looking at the pressure readings that the compressor is not doing anything. On another note, never in a million years would I put a used compressor on a vehicle, you may just end up with more problems than what you have now.
 

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Some of the codes itâ€s throwing out of code reader.



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Hainey
You should address all the other codes first. Looks like you need a new water pump based on the codes you pulled.
If you do open the system, the drier should be replaced.
If the compressor blew up, the condensor should be checked and likely replaced. The whole system needs to be cleaned out.
Good luck
Fred

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