AC Takes forever to blow cold.

[andrewwynn]

The magnetic clutch as upallnight has described can also explain intermittent AC function. Even if 99.5% of the time those symptoms say the compressor is shot:

1) you are flying blind without the tool to tell you what's what
2) the tool will for sure confirm you are correct when you can verify the compressor is not compressing until it wants to
3) you will definitely want the gauges if the compressor is shot because you'd be foolish to risk hurting a brand new compressor flying blind without the right tools.

So, yes you might be 99% on with just the overnight diagnosis but you'll be 100% when you confirm with the right tool.

[Crowz]

Originally Posted by andrewwynn

The magnetic clutch as upallnight has described can also explain intermittent AC function. Even if 99.5% of the time those symptoms say the compressor is shot:

1) you are flying blind without the tool to tell you what's what
2) the tool will for sure confirm you are correct when you can verify the compressor is not compressing until it wants to
3) you will definitely want the gauges if the compressor is shot because you'd be foolish to risk hurting a brand new compressor flying blind without the right tools.

So, yes you might be 99% on with just the overnight diagnosis but you'll be 100% when you confirm with the right tool.

A weak ac clutch will come and go during a day of use if it engages at all. So again if after running the car for a bit it cools fine for the rest of the day its the compressor.

The "tool" as you put it will show no pressure with the clutch engaged or not. So its not going to diagnose the variable compressor even if it had a bad clutch. Also all compressors sold today for the x5's comes with a new clutch.

A set of gauges are not going to diagnose this problem. The are nice to have when charging the system after changing to compressor but your not going to solve this one with gauges.

It cools or it doesn't when this is the problem. If its not cooling the gauges shows nothing and the air out the vent is hot.

If its cooling it shows pressure and the air out the vent is cold. Not any new data here via the gauges that you didn't have already just by feeling the air coming out the vents.

Any other problems then sure gauges are the way to go for the most part but when it comes to this unique problem on the x5's at least when it wont cool when first used for the day but works fine all day long till you let it sit just replacing the compressor is the correct solution always.

My e70 does the same thing but its in the early stages or by design. It doesn't cool for about a minute or longer when first cranked. It will get worse with time.

The symptoms for this problem start with 2 minutes then 5 then 10 and then 30 minutes.

Then its over an hour.

The e53 was taking as long a 2 hours right before I replaced the compressor finally.

I have been fixing a/c systems for about 30 years and have never run into this till the E53 did it and after researching it I found plenty of tech papers on it and others that had the same issue. I had never dealt with vehicles using the variable compressors before this.

As for gauges I have some rather nice ones but again they were useless for diagnosing this particular issue. I could see the high side and low side pressure. I could see the high side temperature and low side temperature with my gauges. They displayed everything I needed to know from type of Freon, amount needed for the charge, recommended high and low side pressure readings, ideal low and high side temperatures, etc. But again they were useless for fixing this particular problem.

[snik]

Originally Posted by Crowz

A weak ac clutch will come and go during a day of use if it engages at all. So again if after running the car for a bit it cools fine for the rest of the day its the compressor.

The "tool" as you put it will show no pressure with the clutch engaged or not. So its not going to diagnose the variable compressor even if it had a bad clutch. Also all compressors sold today for the x5's comes with a new clutch.

A set of gauges are not going to diagnose this problem. The are nice to have when charging the system after changing to compressor but your not going to solve this one with gauges.

It cools or it doesn't when this is the problem. If its not cooling the gauges shows nothing and the air out the vent is hot.

If its cooling it shows pressure and the air out the vent is cold. Not any new data here via the gauges that you didn't have already just by feeling the air coming out the vents.

Any other problems then sure gauges are the way to go for the most part but when it comes to this unique problem on the x5's at least when it wont cool when first used for the day but works fine all day long till you let it sit just replacing the compressor is the correct solution always.

My e70 does the same thing but its in the early stages or by design. It doesn't cool for about a minute or longer when first cranked. It will get worse with time.

The symptoms for this problem start with 2 minutes then 5 then 10 and then 30 minutes.

Then its over an hour.

The e53 was taking as long a 2 hours right before I replaced the compressor finally.

I have been fixing a/c systems for about 30 years and have never run into this till the E53 did it and after researching it I found plenty of tech papers on it and others that had the same issue. I had never dealt with vehicles using the variable compressors before this.

As for gauges I have some rather nice ones but again they were useless for diagnosing this particular issue. I could see the high side and low side pressure. I could see the high side temperature and low side temperature with my gauges. They displayed everything I needed to know from type of Freon, amount needed for the charge, recommended high and low side pressure readings, ideal low and high side temperatures, etc. But again they were useless for fixing this particular problem.

So what do you make of my issue.
Cools well at start up. But usually after some time driving. It stops cooling.

If I park and come back maybe 20, 30 minutes later. It works fine. But eventually cuts out again.
2 weeks ago I had it purged and recharged.
Worked flawlessly for a week, but it's basically back to its old self.
The guy didn't test anything when he recharged it. Said nothing looked out of the ordinary.
I'm thinking I'm leaking freon. What do you think?


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[wpoll]

Originally Posted by snik

So what do you make of my issue.
Cools well at start up. But usually after some time driving. It stops cooling.

If I park and come back maybe 20, 30 minutes later. It works fine. But eventually cuts out again.
2 weeks ago I had it purged and recharged.
Worked flawlessly for a week, but it's basically back to its old self.
The guy didn't test anything when he recharged it. Said nothing looked out of the ordinary.
I'm thinking I'm leaking freon. What do you think?


Sent from my iPhone using Tapatalk

First off, I only know enough about refrigeration to be dangerous...

But, I see "heat pumps" (as we call domestic A/C-Heating systems here in NZ) do this all the time. When pushed hard, either heating or cooling, they freeze up the indoor or outdoor heat exchanger (depending on the phase of operation). Then they will basically do nothing until they thaw, either through ambient thawing or via operational phase inversion.

But of course, cars are a little different. My own X5 has sometimes exhibited this behaviour on long summer trips when the A/C is running for long periods. It's cooling great for an hour or two, then suddenly it stops cooling so well. But 10-15 minutes later it's icy cold again. I can alleviate this somewhat by setting the temperature a little warmer so the system isn't working so hard and it seems to occur less often. I can only imagine that the expansion valve or something is freezing up and then the system has to wait until it thaws (as it cannot reverse the operational phase as a heat pump can).

But of course, while my home town isn't actually in Antarctica, we can see it from here, and I don't use the A/C very much at all - not like folk in the US mid-west or Texas etc. So I haven't worried about this too much...

[snik]

Originally Posted by wpoll

First off, I only know enough about refrigeration to be dangerous...

But, I see "heat pumps" (as we call domestic A/C-Heating systems here in NZ) do this all the time. When pushed hard, either heating or cooling, they freeze up the indoor or outdoor heat exchanger (depending on the phase of operation). Then they will basically do nothing until they thaw, either through ambient thawing or via operational phase inversion.

But of course, cars are a little different. My own X5 has sometimes exhibited this behaviour on long summer trips when the A/C is running for long periods. It's cooling great for an hour or two, then suddenly it stops cooling so well. But 10-15 minutes later it's icy cold again. I can alleviate this somewhat by setting the temperature a little warmer so the system isn't working so hard and it seems to occur less often. I can only imagine that the expansion valve or something is freezing up and then the system has to wait until it thaws (as it cannot reverse the operational phase as a heat pump can).

But of course, while my home town isn't actually in Antarctica, we can see it from here, and I don't use the A/C very much at all - not like folk in the US mid-west or Texas etc. So I haven't worried about this too much...

Nevermind. I see what it is. It's not what I thought it was.


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[FRod1981]

Sounds like likes Somethings freezing up and telling the compressor to shut off. Then it warms up and melts when you shut it off. Only to refreeze again when you drive

[snik]

Originally Posted by FRod1981

Sounds like likes Somethings freezing up and telling the compressor to shut off. Then it warms up and melts when you shut it off. Only to refreeze again when you drive

Hmmm. Like not enough oil?
Then why did it change and run great for a week before it acted up again?


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[FRod1981]

Originally Posted by snik

Hmmm. Like not enough oil?
Then why did it change and run great for a week before it acted up again?


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Check the above post from Wpoll. He makes more sense than I do

[snik]

I'm seeing that this expansion valve fails a bit easily.
It's cheap too. I'm guessing I can't replace it within capturing all the freon. Put the new valve, then refill the system?


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[andrewwynn]

When AC works great from a cold start every time but Peters off also basically every time, that's textbook case of to little freon. The reason: with less freon it's easier for the compressor to make more of a difference between high and low pressure (eg 25 psi to 235 psi) where when properly filled the pressure difference might be 45 to 245, the cooking efficiency goes up and the evaporator gets below 32°F and ices up.

If while driving you can simply turn the AC off for 10 minutes and get cold air again and especially if it's on the order of 35-40° coming out it's a near certainly that is the problem.