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A/C blowing hot air

Tiny
DAVID2063
  • MEMBER
  • 2012 NISSAN MURANO
  • 3.5L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 120,000 MILES
Low side pressure is on high side and A/C clutch not engaging. Ran Nissan diagnostic test and determined A/C coil was bad. Replaced clutch assembly. During repair found that old coil had burnt out. Now diagnostic test shows coil is actuating clutch however the clutch still does not engage when A/C is on. Suspect the low side switch is preventing clutch from engaging.

Any suggestions on what to try next?
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Monday, June 8th, 2020 AT 5:40 PM

8 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Do you have your low and high side pressures using a gauge set? Depending on what these are when the A/C is on we can figure out what is happening. Clearly if the compressor is not coming on then they will be static pressures but that is okay. Just let me know what they are and if you want to jump the compressor and get the pressures with it on that would help as well.

Thanks

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak
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Monday, June 8th, 2020 AT 6:34 PM
Tiny
DAVID2063
  • MEMBER
  • 5 POSTS
I do not have gauges for high and low side readings. Is there a easy way to get this at an auto parts stores without buying the equipment? More details on the problem. Initially checked the Freon level and gauge indicated low side was high and to take to a mechanic. Also noticed the clutch was not engaging. Auto shop said compressor needed to be replaced. I questioned what the problem was they indicated clutch not engaging. Asked if they could replace coil or assembly rather whole compressor, they will only replace compressor. I replaced clutch assembly for much less than a new compressor. Nissan has a diagnostic mode where you can check various relays. Running this I could hear clicking from the relay activating the coil and could see the clutch plate moving as well. This confirmed to me that the coil had power and was working. From research I did online the coil failure is a fairly common issue with the Murano. I have also included a photo of the old coil showing what I think is the defect.
Is it logical that the coil failed and caused the low side to have high pressure? Or could it be the other way that the high pressure caused the coil to fail?
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Tuesday, June 9th, 2020 AT 4:59 AM
Tiny
DAVID2063
  • MEMBER
  • 5 POSTS
Update: added refrigerant and compressor same on. Car cycles between 30 psi to 55 psi. It cools okay but still not as cold as normal. Is this normal to cycle like this. Should I add more refrigerant?
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Tuesday, June 9th, 2020 AT 4:47 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
What was the outside/ambient temperature when you were taking these pressure readings? Also, do you have the high side pressures as well? Clearly we are making progress but with this info we can figure out the issue. However, I assume we are going to need to add a little bit more but depending on the ambient temp the system maybe full so let's start there. Thanks
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Wednesday, June 10th, 2020 AT 5:55 PM
Tiny
DAVID2063
  • MEMBER
  • 5 POSTS
I am not positive about the ambient temperature for last reading I believe it was around 85 degrees F. I do not have a high side reading yet, might be able to get that in a few days.
I just checked the low side pressure and it cycling as the compressor goes on and off between 23 and 50 psi. The ambient temperature is 79 degrees.
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Thursday, June 11th, 2020 AT 8:12 AM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. That is great info. Clearly we are still guessing until we get the high side but that narrows it down. Take a look at this diagram.

At 80 degrees your low side pressure should cycle between 40-55 PSI. The fact that your low side is going from 23 to 50 shows that it could be low on Freon. To confirm this we need the high side pressure to see if it is low as well.

There is a chance that we have a blockage in the expansion valve or other restriction in the high side but the way to confirm this would be getting the high side pressure as well.

If it were me, I would try to just put some more Freon in it and see if that low side pressure comes into line.

Let me know what you find. Thanks
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Thursday, June 11th, 2020 AT 6:48 PM
Tiny
DAVID2063
  • MEMBER
  • 5 POSTS
Got loner manifold gauge set, however high side was leaking some. Ambient temperature is 63 degrees, low side cycled between 18-47 psi and high side between 80-105 psi. Seems like both are low indicating add Freon. Would you expect small leak in high side to change results. Will get another loner hopefully that does not leak.
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Monday, June 15th, 2020 AT 2:33 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Yep. I think you are on top of it. Both sides are low which indicates it needs more Freon. If you have a leak on the high side then that is going to leak refrigerant faster as it is high pressure.

We need to find and fix that first before we go any further or you will just be wasting Freon.

Here is a guide that helps with leak detection:

https://www.2carpros.com/articles/air-conditioner-leak-detection
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Tuesday, June 16th, 2020 AT 4:05 PM

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