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A/C not working?

Tiny
MAURO MAURO
  • MEMBER
  • 2004 BMW X5
  • 3.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 235,000 MILES
Hi, the A/C takes 8 minutes to give cold air. It works regularly if I stop and go. I performed vacuum and charge with 1 kg refrigerant. 86° low pressure 53 PSI high pressure 280° The auxiliary fan go on when rice 190°. I change the fan switch sensor. No better results the same delay. I read that could be the compressor sticks and later 8 minutes go on and maybe ice 32 can help. What you think?
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Monday, July 26th, 2021 AT 5:34 PM

9 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
That is great info. The fact that the pressure seems good makes me think that the compressor is not the issue. However, were these pressures taken when the A/C was blowing warm?

Here is a guide that will help with this info:

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

If these pressures are this way when it is blowing hot and then cold after it starts working then the likely issue at that point is a blend door issue.

Here is a guide that helps with this:

https://www.2carpros.com/articles/replace-blend-door-motor

Below you will find a chart of proper pressures so let's just make sure these pressures are the same when it is hot and cold and we can go from there.

Thanks
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Tuesday, July 27th, 2021 AT 4:57 PM
Tiny
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Thank you for your availability. Here's what happens: after the car has been stopped for a couple of hours, it blows hot air by touching the plate the compressor is engaged I only read the minimum pressure and it is high and it does not go down as it should. After 10 minutes all ok cold air and regular pressures. Unplugging the pressure sensor connector I hear a change in rpm if the engine has more load and the secondary fan starts at maximum speed. But the pressure does not go down. Other posts say that the variable load compressor stops and then, when released, stabilizes and pressurizes the system. I would like to add a couple of ounces of ICE 32 to increase the viscosity but I think I was going to recover the same amount of PAG. Any suggestions? Have a nice night.
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Tuesday, July 27th, 2021 AT 6:23 PM
Tiny
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I could use my jellowjack oil pump to add the ICe 32 from the low pressure port while the system is under normal operating pressure.
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Tuesday, July 27th, 2021 AT 6:26 PM
Tiny
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  • MEMBER
  • 6 POSTS
Also, I don't know I is normal that the auxiliary fan follow only the engine temperature and does not go on when I first start the A/C.
Could be this part: A/C Compressor Control Valve for Calsonic CSV717 CWV615 BMW X5 Nissan 350Z 240SX to replace?
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Tuesday, July 27th, 2021 AT 6:36 PM
Tiny
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  • MECHANIC
  • 18,907 POSTS
The fan issue sounds normal. However, what is the pressure when the system is blowing hot? Did you say that you are reading minimum pressure but it does not go down as it should?

I am not sure I understand that. However, if I am understanding that the pressure is low when the A/C is blowing hot and then goes normal when it blows cold, then we may have a restriction in the system like the orifice tube.

However, this will show in the pressures so what is the high and low side when this is blowing hot and the compressor is on?
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Tuesday, July 27th, 2021 AT 7:30 PM
Tiny
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Hi here my answers: The fan issue sounds normal. However, what is the pressure when the system is blowing hot?
Low port about 100 psi I don't take the high sport.
Did you say that you are reading minimum pressure but it does not go down as it should?
Yes

I am not sure I understand that. However, if I am understanding that the pressure is low when the AC is blowing hot and then goes normal when it blows cold, then we may have a restriction in the system like the orifice tube.
Okay but after 10 minutes the pressure becomes perfect and the system work (if there is a restriction it can be intermittent?)

However, this will show in the pressures so what is the high and low side when this is blowing hot and the compressor is on?
I have to take the both pressure again!
Sorry for my English I am italian.
Thank you
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Wednesday, July 28th, 2021 AT 4:39 AM
Tiny
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Your English is great. Thanks for the clarification.

If the low side pressure is 100 PSI when this is blowing normal then the compressor is not engaged or operating properly if it is engaged.

While we don't know what the high side pressure is yet, I would bet this is going to be about the same as the low side which means that is a static system. In other words, the compressor is not operating to create the pressure difference like it needs too.

Take a look at this chart. I suspect your outside temp was around 90-100 degrees F and if it was then that is why your low side was 100 PSI. So if the high side matches that then this would mean your low side has higher then normal pressure, and the high side has lower then normal when the compressor is running. Looking at the chart that is pointing to the compressor.

Please confirm the high side is lower then normal when it is blowing hot and then I would be looking to replace the compressor or figure out why it is not coming on. If you have no voltage at the compressor when it is blowing hot then it is not being commanded on.
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Wednesday, July 28th, 2021 AT 4:53 PM
Tiny
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Thanks for the clarifications. It seemed to me that the clutch was engaged because the central disc was turning. But now I want to check the electrical voltage to the compressor when it's not good. Could it happen that the front disc turns and the compressor is not integral with the plate? I also have a couple of questions: does evacuating a loaded system from an old charging machine extract all the oil from the compressor? The mechanic who did the refilling after the empty added POE oil without dosing it! I don't think it's a normalized procedure. I have a vacuum pump but I did not want to discharge gas into the atmosphere and I went to a workshop for vacuum and refilling. I was surprised by the age of the charging equipment and the method. I think here in Florida it's a bit like South America. Best
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Wednesday, July 28th, 2021 AT 6:17 PM
Tiny
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That is correct. Just because the center disc is spinning does not mean it is operating. That is what the pressures will tell us. However, the center disc spinning tells us that we are getting voltage needed to turn it on. However, there is a clutch inside that plate that needs to transfer the spinning of the pulley by the belt to the compressor. So we apply voltage to the clutch to get it spinning. However, that clutch can slip or not actually engage causing no pressure change.

You are correct as well about just opening the system. Not only is it not helpful to the atmosphere but it is just a waste of money.

Here is a guide that will show how to do it if you need it:

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system
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Thursday, July 29th, 2021 AT 6:58 PM

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