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AC not blowing cold all of the time
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void00
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Jul 9, 2023, 2:07 PM
Post #1 of 14
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AC not blowing cold all of the time
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Car: 2013 Nissan Sentra S 1.8L 6spd
My car's AC doesn't blow cold air all of the time. I took it to a shop where they did an evac and recharge with dye and found no leaks. I was told the compressor was not engaging all of the time and was recommended a new compressor + condenser + expansion valve for $2000. When I asked for some more information about the issue I got contradictory answers from the shop so I'm posting here for some insights.
I rented a manifold gauge set and took some readings, I also noticed the the values remained at what's shown and did not cycle. Visually I can see (and hear) the clutch engaged when I turn the AC on but I don't know if it's slipping.
Pressure gauge readings (PSI) taken at 67F air temp:
AC Off for 3 mins - Low: 85 High: 100
AC On - Low: 46 High: 135
AC OFF:
AC ON:
Here are the specs:
Any help is appreciated!
Some more info (not sure if it's useful):
Sometimes the air coming out the vent is crisp cold (very rare), sometimes it's cold only at high RPMs and most of the time it's the same temp as the outside air.
I did notice something with the RPM while idling with a warm engine:
AC Off : 450RPM
AC On (no cold air) : 600RPM
AC On (cold air) : 450RPM
As I mentioned above, I did not see or hear the compressor turn on and off, it was just constantly on. I do hear the fan in front of the condenser cycling sometimes.
I'm okay with DIY ing the repair if I know what is causing the issue, I can get the system evacuated at a shop before I do anything.
(This post was edited by void00 on Jul 9, 2023, 2:20 PM)
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Hammer Time
Ultimate Carjunky
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Jul 9, 2023, 2:18 PM
Post #2 of 14
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Re: AC not blowing cold all of the time
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First you need to post the year, make, model and engine size with any question.
What you are describing is the compressor not engaging intermittently which would be an electrical problem and require some electrical testing only WHEN THE PROBLEM IS OCCURING.
It sounds like the shop that looked at it didn't reproduce the problem and is merely guessing.
There is overkill with the parts they are recommending. It tells me they are just trying to change everything so they can't miss. Well, if it's an electrical problem with switches or the wiring, guess what, they missed and it would all be for nothing.
edit,
OK, I just saw the pressures. That can mean a few things.
The compressor could be weak'
It is low on refrigerant and the fans haven't kicked in yet
Stuck open expansion valve although not know what kind of vehicle this is, the pressures can vary.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Jul 9, 2023, 2:22 PM)
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void00
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Jul 9, 2023, 2:33 PM
Post #3 of 14
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Re: AC not blowing cold all of the time
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Hey thanks for replying! I did put the details of the car in the first line, I added the engine size to it now :)
Glad I'm not the only one who thought what they suggested was a bit overkill. Do you have any guide I can follow for electrical testing? I can think of testing the relay, continuity in the wires and maybe replacing the compressor control valve.
Edit:
Not sure if the pictures are loading on your device so I'll just put them in text here. According to the maintainance manual of my car (2013 Nissan Sentra S 1.8L 6spd) the pressure on the high side should be 131.8 - 161.2 and on the low side it should be 23.1 - 28.1. (At 77F)
This was after the shop did an evac and recharge with dye, I'm assuming they filled it with the proper amount but I'm not sure
(This post was edited by void00 on Jul 9, 2023, 2:39 PM)
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Hammer Time
Ultimate Carjunky
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Jul 9, 2023, 2:37 PM
Post #4 of 14
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Re: AC not blowing cold all of the time
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Sorry, I missed the car info.
If you're going to try to fix this yourself you need to know how to read and follow a wiring diagram and possess a test light that shows both power or ground.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Hammer Time
Ultimate Carjunky
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Jul 9, 2023, 3:21 PM
Post #6 of 14
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Re: AC not blowing cold all of the time
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No, that was a continuity tester.
You need one of these that connects to both power and ground and can identify either power or ground when testing like this but if I have to explain this to you it is unlikely you will be able to follow a wiring diagram.
This light lights up red for power and green for ground.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Jul 9, 2023, 3:22 PM)
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void00
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Jul 9, 2023, 3:35 PM
Post #7 of 14
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Re: AC not blowing cold all of the time
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Alright, thanks a lot for you help. I'll see if and what I can do over the coming weeks.
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Hammer Time
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Jul 9, 2023, 3:45 PM
Post #8 of 14
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Re: AC not blowing cold all of the time
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Remember, you can only do electrical testing when the problem is present.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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void00
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Jul 9, 2023, 3:53 PM
Post #9 of 14
(1668 views)
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Re: AC not blowing cold all of the time
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Thanks! My AC is manual. Do you have a higher resolution image by any chance? Or the name of the website where I can find it
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Hammer Time
Ultimate Carjunky
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Jul 9, 2023, 4:04 PM
Post #10 of 14
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Re: AC not blowing cold all of the time
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You can't access that. It's a professional subscription service. I'm not even supposed to be posting this.
Try this. This is the largest file the site allows for upload.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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void00
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Jul 9, 2023, 4:10 PM
Post #11 of 14
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Re: AC not blowing cold all of the time
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Thank you. I can read the second image, really appreciate it!
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Tom Greenleaf
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Jul 9, 2023, 10:52 PM
Post #12 of 14
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Re: AC not blowing cold all of the time
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Whoa? It's 67F ambient temperature? At about there if real air temp stop and wait for warmer air that's pretty cold to test things out is close to when things will shut down on purpose?
Homes or vehicles that's about all you expect to get inside an area to be in many would be too cold at that.
IDK how you test things if those temps are correct it's probably wrong measurements?? Verify all that or wait for a warmer time??
Tom
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void00
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Jul 10, 2023, 11:10 AM
Post #13 of 14
(1564 views)
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Re: AC not blowing cold all of the time
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Hey, thanks for letting me know about that. I'm new to this and I wasn't aware. I'll wait a couple days till it gets warmer and then update this post with new readings which could help in making better diagnosis.
PS: It was 90F+ for the past 2 weeks and now it's just cloudy. Good for me as my AC isn't working but bad for diagnostics I guess xD
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Tom Greenleaf
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Jul 10, 2023, 11:28 AM
Post #14 of 14
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Re: AC not blowing cold all of the time
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Temps swings where I am are normal. Yes you can do some things but knowing real performance NO.
With equipment you can vacuum and charge if you could force in a charge.
IDK the few with all that would just charge X and say come back later to see how well it really works.
A/C will kick on in quite cold just engine heat warms area when super cold if just parked but shut down right away too opposite time of year air temps might not get out of teens (F) so just a pest for diagnostics.
Forever haven't knows of a place that heats a shop area much above 40F in only so things don't freeze (assorted products around) opening doors all the time kills chances of heat none A/C the shops TMK you sweat it! Tom
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