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2012 VW Passat, AC cold on the Passenger side progressively gets hotter to the driver side
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Bryan2024
New User
Aug 11, 2024, 1:36 PM
Post #1 of 7
(2908 views)
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2012 VW Passat, AC cold on the Passenger side progressively gets hotter to the driver side
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2012 VW Passat, 2.5L, 100K+ miles
Dual climate controlled
AC would not blow cold and took a while for it to just blow cool. I took it to a shop and was told it needed to be serviced, “it was a little low on refrigerant”. I went to pick it up after they serviced it and the tech noticed it was not blowing cold after the service. Told me to bring it back.
On the way home it started to blow cool when I got the car above 50 mph, blow warm at the red lights. Eventually it blew cool even at the red lights. I just new it needed a new condenser fan but when I popped the hood when I got home it was on. I let the car sit overnight. Turned it on in the morning and the condenser fan did not come on, ac blows warm. Once the engine hit the operating temp the radiator fan and the condenser fan kicked on at the same time and ac blew cool.
I did some research and found out the AC compressor solenoid valve will cause my issues to include not commanding the condenser fan to come on when needed.
I ordered a RKX AC Compressor Control Solenoid Valve Compatible with Audi and Volkswagen Compressors made by Sanden PXE16 PXE14 MK5 MK6 B8 TDI.
I do not have AC testing/evac/vacuum/charge tools/equipment. So, I took the car to a shop, and they removed the refrigerant. I replaced the solenoid. Took it back to the shop and they vacuumed down and charged the system.
AC blew cold on the way home. I also verified the condenser fan now comes on when the engine is cold.
It’s my son’s car and he didn’t drive it for weeks after I replaced the solenoid, I got a call the other day its blowing hot again.
Here is my new issue, with AC on, center vents only. Far right passenger side 47 degrees, passenger center, 55 degrees, driver center 60 degrees and driver far left 74 degrees. The temp readings were taken at idle and 86 degrees was the outside temp. However, when taking these readings when the temp is 100 degrees outside, they are all 10+ degrees higher.
I don’t think I have HAVC blender door or actuator issues. Maybe an internal temp sensor issue? I also read that incorrect refrigerant can cause this issue, but the shop told me they put the factory recommended amount in it.
Any help, directions or advice on what to do from here would be greatly appreciated.
Also, I found a post on this site that had the same thing happen after they replaced the solenoid, but the individual never reported back on what the repair/fix was.
/gforum.cgi?url=http://
Thanks,
Bryan[
(This post was edited by Hammer Time on Aug 11, 2024, 1:58 PM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Aug 11, 2024, 1:56 PM
Post #2 of 7
(2904 views)
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Re: 2012 VW Passat, AC cold on the Passenger side progressively gets hotter to the driver side
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I don't know what you are reading but NOTHING in that thread refers to a solenoid valve.
What they discussed was the high pressure blow-off valve. It's a safety valve in all compressors that releases the refrigerant when the pressure goes way too high and after that happens once the valve has to be replaced or it will contin ue leaking.
Your problem started with a refrigerant leak that you never addressed. You are probably low on refrigerant again.
Also, just because a fan is turning doesn't mean it's running at full speed. It could be tired.
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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.
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Bryan2024
New User
Aug 11, 2024, 2:38 PM
Post #3 of 7
(2900 views)
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Re: 2012 VW Passat, AC cold on the Passenger side progressively gets hotter to the driver side
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Yes, they had a pressure relief valve discharge on them as well. You must have skimmed over the part of them replacing the solenoid on the compressor, their original issue. I have provided a copy and paste below from their original post for reference. I referenced that post because they replaced the solenoid as I had and also had about the same temperature difference between the driver and the passenger side as I am having.
“My AC in my 2012 Passat was working intermittently, mostly not working. Refrigerant pressures were fine. After researching I found that a common issue is the solenoid on the compressor.
I ordered a new one. Removed old r-134, replaced the solenoid, vacuumed the system for about an hour. Then held the vacuum for another 45 minutes and it held pressure. I added r-134 back to the system and the compressor kicked on and blew cold.
I took it for a drive and then that’s when the issues started. First, there was about a 15 degree difference between the driver and passenger side vents (passenger side about 54 driver side near 70.
One I got home, the car sat and idled for a few minutes and then the pressure relief valve on the compressor opened up and discharged an unknown amount of refrigerant.”
Thank you for the advice, I will look for leaks and also look into whether or not the fan is worn out.
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Hammer Time
Ultimate Carjunky
/ Moderator
Aug 11, 2024, 3:00 PM
Post #4 of 7
(2894 views)
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Re: 2012 VW Passat, AC cold on the Passenger side progressively gets hotter to the driver side
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Your are totally barking up the wrong tree with that solenoid. The job of that solenoid is to use Pulse Width Modulation to control the compressor turning off and on. That compressor clutch stays constantly engaged and it's regulated with the solenoid. It has nothing to do with the cooling fan.
The fan is controlled by input to the PCM of a pressure sensor located behind the right kick panel.
The fan also has a control module located on the fan itself.
As you are finding out, AC diagnosis is not a DIY type repair. It requires years of experience and observing many details in the system operation.
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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.
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Hammer Time
Ultimate Carjunky
/ Moderator
Aug 11, 2024, 3:19 PM
Post #5 of 7
(2887 views)
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Re: 2012 VW Passat, AC cold on the Passenger side progressively gets hotter to the driver side
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A/C Pressure Switch (F129)
NOTE
♦ For switching pressures, removing and installing switches and switch arrangement and version, see vehicle-specific refrigerant circuit.
This pressure switch has 3 functions:
1. Switches the coolant fan to the next higher level when the pressure in the refrigerant circuit increases (approximately 16 bar (232 psi)).
2. Switches off A/C system if pressure is excessive (approximately 32 bar (464 psi)), for example. because of insufficient engine cooling.
3. Switches off A/C system if pressure is insufficient (approximately 2 bar (29 psi)), for example. loss of refrigerant.
NOTE
♦ A/C Pressure Switch (F129) replaces the A/C Refrigerant High Pressure Switch (F23) , A/C Refrigerant Low Pressure Switch (F73) and the Magnetic Clutch High Pressure Switch (F118).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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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Bryan2024
New User
Aug 11, 2024, 3:41 PM
Post #6 of 7
(2883 views)
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Re: 2012 VW Passat, AC cold on the Passenger side progressively gets hotter to the driver side
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I don’t think I am, plus I replaced the solenoid and now the fan turns on without being forced to when the radiator fan kicks once the engine gets over operating temp.
Listen, all I can do is share the information I found that led me to replacing this solenoid. So yes, the AC Compressor Control Solenoid Valve does play a role in controlling the condenser fan, but it does so indirectly. As you know, this solenoid valve regulates the pressure within the AC system by adjusting the flow of refrigerant. The PCM monitors this pressure, and based on the data it receives, it determines when to activate the condenser fan. If the solenoid valve is stuck (mine was stuck) or malfunctioning, the PCM does not receive the correct pressure data, which can lead to the condenser fan not turning on as it should.
I reached out for help because I am not a subject matter expert when it comes to AC repair that is why I am on this forum, and your right about AC DIY, but when your tight on money and the repair shop just wants to just replace your AC compressor for $1500 you try and do what you can…
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Hammer Time
Ultimate Carjunky
/ Moderator
Aug 11, 2024, 3:48 PM
Post #7 of 7
(2882 views)
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Re: 2012 VW Passat, AC cold on the Passenger side progressively gets hotter to the driver side
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OK, I've been specializing in AC repair for over 40 years in south Florida so I do know a thing about AC.
I'm not guessing here. The info I just gave you came directly for the factory service manual so I'm not going to debate with you.
If you think Dr. Google knows better you go for it.
I'm closing this question now since you don't want to take the advice anyway.
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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.
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