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2012 VW Passat AC issue


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adaustin
User

Jun 2, 2021, 5:22 PM

Post #1 of 26 (1346 views)
2012 VW Passat AC issue Sign In

Hello,

Sorry in advance for the lengthy post but I wanted to include as much information as possible.

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.

Not knowing how much came out I decided to repeat the process of removing, vacuuming and replacing. Afterward, the pressure gauge readings were;

AC not running;
Low side: 100
Hot side: barely registering, maybe 10 at the most

When I turn the AC on the high side remained at 10 and the low side dropped to 5 then slowly increased to around 35 and then the pressure relief valve discharged again.

Is this a sign of a bad compressor, expansion valve or something else?

I’ve been searching the internet for hours and can’t find an answer.

Anyone have suggestions?

Thanks in advance!


(This post was edited by adaustin on Jun 3, 2021, 3:30 AM)


Hammer Time
Ultimate Carjunky / Moderator
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Jun 2, 2021, 6:02 PM

Post #2 of 26 (1340 views)
Re: 2012 VW Passat AC issue Sign In

As you probably realize now, guessing and throwing parts at an AC system will usually make matters worse and cost a lot more in the end.

I'm betting that if you look close when you turn the AC on, the radiator/condenser fan is not coming on. If I'm right you started out with no refrigerant related cooling problem but now you have one.
I'm assuming you didn't measure the amount of refrigerant added either.

One problem at a time, check the fan.



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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 Jun 2, 2021, 6:03 PM)


adaustin
User

Jun 2, 2021, 6:20 PM

Post #3 of 26 (1335 views)
Re: 2012 VW Passat AC issue Sign In

The fan was checked and yes, I did put the correct amount (575 grams, measured with a scale).

The original problem was the compressor not coming on, not the fan.

Thanks,


Hammer Time
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Jun 2, 2021, 6:27 PM

Post #4 of 26 (1329 views)
Re: 2012 VW Passat AC issue Sign In

If your compressor is blowing off refrigerant it's because the pressure has exceeded 400PSI and the most common way for that to happen is the fan not working properly.

You stated the pressures were good before the repair. Not sure how that is possible if the compressor wasn't engaging.



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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.



adaustin
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Jun 3, 2021, 3:26 AM

Post #5 of 26 (1306 views)
Re: 2012 VW Passat AC issue Sign In


In Reply To
If your compressor is blowing off refrigerant it's because the pressure has exceeded 400PSI and the most common way for that to happen is the fan not working properly.


Ok, I originally thought you were saying that my original problem was the fan. It was working properly before but, is not now. I just checked it and the fans are not coming on. Thanks for the input.

The compressor was working "intermittently" before. So, I was able to read the pressures while it was on.

Is the fan issue what's causing the high side pressure to be so low?


Hammer Time
Ultimate Carjunky / Moderator
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Jun 3, 2021, 3:32 AM

Post #6 of 26 (1300 views)
Re: 2012 VW Passat AC issue Sign In


Quote
Is the fan issue what's causing the high side pressure to be so low?


No, that would likely be due to the refrigerant you lost but don't add any until you resolve the fan problem. Those high pressures caused by not having a fan when the car is not moving will destroy your compressor.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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.



adaustin
User

Jun 3, 2021, 4:08 AM

Post #7 of 26 (1296 views)
Re: 2012 VW Passat AC issue Sign In


In Reply To

Quote
Is the fan issue what's causing the high side pressure to be so low?


No, that would likely be due to the refrigerant you lost but don't add any until you resolve the fan problem. Those high pressures caused by not having a fan when the car is not moving will destroy your compressor.


Going to work on the fan issue today. Thanks


Tom Greenleaf
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Jun 3, 2021, 4:32 AM

Post #8 of 26 (1294 views)
Re: 2012 VW Passat AC issue Sign In

Just general adaustin: Most anything with electric fan(s) will not come on if compressor is not engaged. It was with assorted temp observations - vents inside.
I'm thinking also the last resort is blow it out via the pressure release do know some of those do not reset and still seal.
Now charge is unknown again and low so defaults to compressor off, fan(s) off unless also for engine then engine heat is in control.
If you test drove it for observations air speed will lower condenser temps and fans frequently quit as not necessary anymore but it doesn't know it's correct charge or just low again from being cooled.
Just some ramblings on this. If it blew out with a spike about 400 it also probably left an oil mess.
One more: Watch out for erratic pressures with probably a gauge set (manifold) used then don't always get a good connection such that reading is void info.
HT already said/warned to watch out, mistakes will set you back or errors in replacing parts try like all get out to be sure it needed just that item no guessing.
It's not easy DIY stuff when things act up the tuition ($$) of learning that is nasty costly,


T



adaustin
User

Jun 3, 2021, 4:37 AM

Post #9 of 26 (1292 views)
Re: 2012 VW Passat AC issue Sign In

Another thought, wouldn’t the lack of high side pressure keep the high pressure switch from engaging the fan?


adaustin
User

Jun 3, 2021, 5:33 AM

Post #10 of 26 (1284 views)
Re: 2012 VW Passat AC issue Sign In

Ok, I just verified that the fans are working. I let the car idle for a bit, both fans kick on and run and they are removing heat.

Also, I’m thinking a faulty gauge for the high side pressure? I’m going to borrow another manifold set later today and see what readings I get from those.

Would over charging r-134 also cause the pressure relief blow off? Maybe I need to check the scale I’m using to make sure it is accurate?


Hammer Time
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Jun 3, 2021, 6:25 AM

Post #11 of 26 (1281 views)
Re: 2012 VW Passat AC issue Sign In

Of course it would. Make sure the service ports are reading correctly and your scale is accurate. Having enough pressure to blow off refrigerant is serious.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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 Jun 3, 2021, 6:26 AM)


adaustin
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Jun 3, 2021, 9:55 AM

Post #12 of 26 (1268 views)
Re: 2012 VW Passat AC issue Sign In

I got a different set of gauges, now I’m pretty sure the others were faulty. New measurements are;

Engine off: low and high equalized around 100

Engine and ac on: low side bounces between 10 and 25, high side drops to 50

Probably due to the escaped r-134?

I’m thinking about vacuuming the system down again and then slightly undercharging the r-134 to see what happens there.


Hammer Time
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Jun 3, 2021, 10:10 AM

Post #13 of 26 (1262 views)
Re: 2012 VW Passat AC issue Sign In

I wouldn't undercharge it but I would monitor the gauges very closely when you fire it up and immediately shut it down if the high side shoots up.

Observe what the fans are doing in relation to the high pressure readings. From what I can find out, this appears to be a variable speed fan that should increase speed as the pressure rises.



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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.



adaustin
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Jun 3, 2021, 10:27 AM

Post #14 of 26 (1258 views)
Re: 2012 VW Passat AC issue Sign In

Thanks, I’ll give that a shot and see what it does.


adaustin
User

Jun 3, 2021, 1:57 PM

Post #15 of 26 (1244 views)
Re: 2012 VW Passat AC issue Sign In

So, I evacuated and vacuumed the system again. Held vacuum. Began charging, got through the first can with no issues. Compressor kicked on and fans were running the whole time.

Started second can, low side got to around 30, high side around 100. However, before I was even half way through the can the pressure relief valve discharged again!!!

I had only put approximately 510-530g in before it blew and the fans were running the whole time. It calls for 575g.


Hammer Time
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Jun 3, 2021, 2:11 PM

Post #16 of 26 (1239 views)
Re: 2012 VW Passat AC issue Sign In

What was the high side pressure at the time?

If the high side gauge hadn't spiked, then you have to replace the blow off valve. Many of them are not reusable after blowing off once.



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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 Jun 3, 2021, 2:15 PM)


Tom Greenleaf
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Jun 3, 2021, 2:14 PM

Post #17 of 26 (1235 views)
Re: 2012 VW Passat AC issue Sign In

Hmmm > This system is about 19oz total charge. It's VERY low for capacity so a couple ounces are going to seriously matter for performance.
100 high if accurate is low. When all is stable and well you should see about (about means about) 2.5 times the temp (Fahrenheit) in PSI pressure.
So that would mean at 100F entering grille, fan(s) on, compressor staying on and idle up a bit, say 1,500 that's close.
Refrigerant is so temp sensitive it can change dramatically in front of you if in wind or variable fan speed or effectiveness.
It's sometimes just me but non metric measuring pressures/temps and weights match up better to what's going on to me there are charts you see you are close then should expect center vent temps accordingly.
If recharged sometimes I find a run around the block help make it stable not just still in same spot. Fully warmed up engine, some start ups and stops driving then go check again. Leave a thermo in a center vent and watch it perform expectedly or not,


Tom



adaustin
User

Jun 3, 2021, 3:51 PM

Post #18 of 26 (1225 views)
Re: 2012 VW Passat AC issue Sign In


In Reply To
What was the high side pressure at the time?

If the high side gauge hadn't spiked, then you have to replace the blow off valve. Many of them are not reusable after blowing off once.


The high side was barely over 100 at the time.

Ok, didn’t realize that. I figured since it held a vacuum it was good. I’ll look into replacing it. Thanks


adaustin
User

Jun 3, 2021, 3:59 PM

Post #19 of 26 (1221 views)
Re: 2012 VW Passat AC issue Sign In


In Reply To
Hmmm > This system is about 19oz total charge. It's VERY low for capacity so a couple ounces are going to seriously matter for performance.
100 high if accurate is low. When all is stable and well you should see about (about means about) 2.5 times the temp (Fahrenheit) in PSI pressure.
So that would mean at 100F entering grille, fan(s) on, compressor staying on and idle up a bit, say 1,500 that's close.
Refrigerant is so temp sensitive it can change dramatically in front of you if in wind or variable fan speed or effectiveness.
It's sometimes just me but non metric measuring pressures/temps and weights match up better to what's going on to me there are charts you see you are close then should expect center vent temps accordingly.
If recharged sometimes I find a run around the block help make it stable not just still in same spot. Fully warmed up engine, some start ups and stops driving then go check again. Leave a thermo in a center vent and watch it perform expectedly or not,


Tom


Thanks! 100 seemed low to me also, not sure what that means though.


Hammer Time
Ultimate Carjunky / Moderator
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Jun 3, 2021, 4:03 PM

Post #20 of 26 (1219 views)
Re: 2012 VW Passat AC issue Sign In

It means you didn't have enough refrigerant in it yet.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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.



Tom Greenleaf
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Jun 4, 2021, 1:54 AM

Post #21 of 26 (1199 views)
Re: 2012 VW Passat AC issue Sign In

Just a note on those "blow out" valves as a fail safe" or last ditch to save you or it:
Things like that are in assorted use TMK basically spring loaded (I think?) to stop a serious disaster. If they can re-set and work isn't sure to me have witnessed them (others 99%) some used them as the measure of max a system or thing would hold!
They all re-set and sealed - just my observation wasn't my doing.
This one by default didn't seal for the same pressure extreme apparently. Yes it would likely hold vacuum but that doesn't fix one TMK.
I would look for oil evidence or check with a sniffer if you care to verify it but the real answer should be replace it.
Clearly it's throwing off this show now.
IMO it isn't going to allow knowing if there's a reason it blows out till a new one does the same thing. It's not allowing time to see it by gauges or temp I think either would set this type off being A/C not for other use.


Some type of this idea is used in my own air compressor for shop (my shop, my problem to keep working) also for water wells, water heaters with tanks too all over creation I have one of those too it resets tight.
Other: I doubt the quality control of the dang things is better then it was when in use for assorted things this being A/C should know and respond to liquid pressure (is stronger,) vapor pressure and perhaps a given temperature too?
End all: Dump it for new if cheap enough have a spare for this job,


Tom


adaustin
User

Jun 4, 2021, 5:46 AM

Post #22 of 26 (1190 views)
Re: 2012 VW Passat AC issue Sign In

So today I noticed that the compressor is getting EXTREMELY hot! I didn’t take a temp reading but it was scalding hot to the touch, I’m guessing there’s an issue with the compressor causing it to over heat and in turn causing the blow off?

Later today I’ll try to get a temp reading on it but didn’t have time this morning.


Hammer Time
Ultimate Carjunky / Moderator
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Jun 4, 2021, 5:55 AM

Post #23 of 26 (1188 views)
Re: 2012 VW Passat AC issue Sign In

No, get off that track. When you compress refrigerant, it gets hot. That is normal.
Touch the outgoing pipe and you will burn your hand.



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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.



adaustin
User

Jun 4, 2021, 6:13 AM

Post #24 of 26 (1184 views)
Re: 2012 VW Passat AC issue Sign In

Got it, I’ve just never touched one that hot I guess.

Are the pressure relief valves on ac compressors universal. I found this one at NAPA, but it doesn’t say what compressors it fits on.

https://www.napaonline.com/en/p/TEM208840?cid=paidsearch_shopping_dcoe_google&campaign=GSC-Heating-Cooling-Climate-Control&campaign_id=10947735025&adgroup_id=107081865506&adtype=pla&gclid=EAIaIQobChMI0seH-oX-8AIVKD2tBh015QaXEAQYASABEgKA_vD_BwE&


Tom Greenleaf
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Jun 4, 2021, 6:38 AM

Post #25 of 26 (1180 views)
Re: 2012 VW Passat AC issue Sign In

Back a few now: "Extremely Hot." You need to take that temp it does get hot as HT said. How hot is the blowout temp? It's not as hot as a good heater blowing air in some vehicles is off my charts but roughly 182F. Water, metal or liquid would burn you + air would take a while or wouldn't unless focused. That's caloric value of "stuff." T






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