Confused about AC

[ITSPREZ]

Any help/direction appreciated!

2001 Jetta ALH with original Sanden SD7V16 (1J0 820 803 F)

AC worked when parked years ago due to accident, brining it back to life for my 16 y/o daughter who has fond memories traveling the country in it and wants it for hers !

May 23rd:
AC blows air same temp as outside
Outside temp 85 degrees
Low side 0 psi
High side 0 psi
Neither fan comes on
Compressor does not come on (clutch not spinning)

May 24th:
AC blows air same temp as outside
Added 12oz 134a
Outside temp 78 degrees
Low side 95 psi
High side 99 psi
Both fan comes on
Compressor comes on (clutch spinning)
AC still blows same temp as outside
Tried to add additional 134a (12oz of 26oz already put in)
Won’t pull in any more 134a

Not new to repairs to this car (owned it since 2003) but AC ignorant.

Let me know more information would be helpful.

 

[Nuje]

If it was completely drained / empty before, doesn't it need some PAG oil and a replacement drier as well?
(Also AC ignorant, but trying to figure it out on my own car, too.)

 

[ITSPREZ]

I did not drain or flush it (I did pull a vacuum) so I figured the PAG was still in it, I did purchase PAG 46 but the Sanden SD7V16 label says it requires SP-10 which I cannot find anywhere. No luck yet on finding cross reference between PAG and SP-10 yet.

 

[ITSPREZ]

When I say pulled a vacuum, I mean I let it sit for a couple hours and at -30psi (-1 bar) and it showed no signs of a leak.

 

[03TDICommuter]

If it was zero pressure, you have a leak. What did you use to monitor pressures? Just dial gauges? If so, they won't show a tiny tiny leak. Look for oily wet connections - that's where your leak is.

With zero pressure, yes I would change the drier. BTW, R134A charge is weighed in. Doing it by pressure doesn't work well. That said, the fact you don't have a pressure differential tells me you either have a stuck open valve in the compressor, or your compressor clutch isn't really engaging and spinning.

I would not add any PAG

 

[Mongler98]

Even -30 for 1 year sitting is no inditactio of a leak. It's a worthless test. You need to charge the system with 295 psi of nitrogen to determine if you have a leak!.
The area of a leak anywhere like a pinhole or what not is so small that the atmospheric pressure on it is only about 0.5psi. Aka 1psi is 1 lb of pressure per square inch.
It's a good way to tell before you fill with nitrogen to test so it's not wasted on a big leak... but its impossible otherwise.
Stop taking bad advice on ac from YouTube

You might be using harbor frieght gauges... worthless junk.
You dont have a leak. The 1st pressure reading was you not using the tools correctly.
You have other issues.
1st is to get the compressor to turn over. If the clutch is making it spin and it's got 12v and you have no pressure difference on low to high... its trashed.

Its impossible to add anything if the compressor is not working.

 

[ITSPREZ]

If it was zero pressure, you have a leak. What did you use to monitor pressures? Just dial gauges? If so, they won't show a tiny tiny leak. Look for oily wet connections - that's where your leak is.

With zero pressure, yes I would change the drier. BTW, R134A charge is weighed in. Doing it by pressure doesn't work well. That said, the fact you don't have a pressure differential tells me you either have a stuck open valve in the compressor, or your compressor clutch isn't really engaging and spinning.

I would not add any PAG

Yes just dial gauges were used to see zero pressure then after adding 12 oz to see the low side 95 and the high side 99.

The clutch is spinning, I took a video of it starting and stopping when I turn the AC on and back off but can’t seem to attach it here.

I was attempting to add (by weight) the remaining 134a but it would not pull Ain from the second 12 oz can.

The clutch is spinning, I took a video of it starting and stopping when I turn the AC on and back off but can’t seem to attach it here.

Didn’t see any oily wet spots. Guess I will need to add dye and look for leak that way.

 

[ITSPREZ]

Even -30 for 1 year sitting is no inditactio of a leak. It's a worthless test. You need to charge the system with 295 psi of nitrogen to determine if you have a leak!.
The area of a leak anywhere like a pinhole or what not is so small that the atmospheric pressure on it is only about 0.5psi. Aka 1psi is 1 lb of pressure per square inch.
It's a good way to tell before you fill with nitrogen to test so it's not wasted on a big leak... but its impossible otherwise.
Stop taking bad advice on ac from YouTube

You might be using harbor frieght gauges... worthless junk.
You dont have a leak. The 1st pressure reading was you not using the tools correctly.
You have other issues.
1st is to get the compressor to turn over. If the clutch is making it spin and it's got 12v and you have no pressure difference on low to high... its trashed.

Its impossible to add anything if the compressor is not working.

I certainly could have made a mistake on my first reading of zero pressure but that is the same method I used to take the 95/99 pressure as well.

I’ll look into the nitrogen advice but likely better to take it to a pro vs investing in those tools???

The gauges I am using are not HF but still only about $100 set.

After reading the information found here and in this post I’m leaning towards bad compressor. It worked when parked but suppose it could have “went bad” while sitting all those years. I expected seals/rings to need replaced but was hoping the main components were okay.

 

[03TDICommuter]

Yes just dial gauges were used to see zero pressure then after adding 12 oz to see the low side 95 and the high side 99.

The clutch is spinning, I took a video of it starting and stopping when I turn the AC on and back off but can’t seem to attach it here.

I was attempting to add (by weight) the remaining 134a but it would not pull Ain from the second 12 oz can.

The clutch is spinning, I took a video of it starting and stopping when I turn the AC on and back off but can’t seem to attach it here.

Didn’t see any oily wet spots. Guess I will need to add dye and look for leak that way.

I've had issues with those quick couplers. Are you sure it's depressing the ball and opening the port up? And you cannot charge into the low side if the low side won't go low. Figure out why you don't have any pressure differential before dumping more refrigerant in there.

And nothing is wrong with those HF gauges.

 

[03TDICommuter]

FWIW, PAG 46 is another name for SP10 from what I read many years ago. Also look here https://www.acparts.com/product/sanden-sp-10-pag-oil-8-45-oz/

 

[ITSPREZ]

I've had issues with those quick couplers. Are you sure it's depressing the ball and opening the port up? And you cannot charge into the low side if the low side won't go low. Figure out why you don't have any pressure differential before dumping more refrigerant in there.

And nothing is wrong with those HF gauges.

Thanks for the tip, I’ll check the quick connections, they worked for the first 12oz but now that there is some pressure in them maybe not anymore.

 

[ITSPREZ]

FWIW, PAG 46 is another name for SP10 from what I read many years ago. Also look here https://www.acparts.com/product/sanden-sp-10-pag-oil-8-45-oz/

Excellent, thanks for the link too!

 

[Mongler98]

Repeat. You can not add refrigerant if the compressor is not operating.

The cost of tools is about $600 and consumables another $100 (nitrogen, acetone, liquid snot and so on)
Any capable shop can do the job for $450 to $500 in labor. Parts are not included. But you can get quality parts once a diagnosis is done.
I always encourage a diy approach to all car stuffs but this and a few other things are so easy to screw up and still think you did a perfect job but just to find out you wasted time and $ down the road.
Take it to somone who offers a garantee.

 

[Mongler98]

Any and all compressors that go bad produce acid.use a $8 acid tester for 134a.
All compressors that fail either have a locked up compressor or a spinning compressor. If you put 12v to the harness to the compressor clutch and the clutch engages and is spinning you should see a little change in pressure but not much. Like 80/150 but it wont be like what you have unless it's really bad. But that is usually a locked up compressor.
Either way it's very easy to diagnose this way.

 

[Mongler98]

If the compressor is shot... you must flush the system properly. No compressed air. It must be nitrogen and you can use acetone to flush but it's a nasty mess. Use proper ac lineset flush stuff its 20x the cost but works 30x better with nearly none of the mess.
You need
1 40 tank of nitrogen (rental is $38 a month plus the $50 to fill it)
1 can of evap lineset cleaner $60
1 adapter for the cleaner to gauge fitting $35
1 rubber cone adapter nozzle $10

Or you can use the $140 kit that you pressurize externally and use acetone or a liquid non foaming cleaner solvent but these are problematic and you still should use nitrogen but you can be careful and use dry paint both grade compressed air. But it takes forever and you need about 5 refills to do the job.
You need to have a vacuum pump that can do a minimum of 500 micron. $350
Micron gauge $165 (use yellowjacket)
A 4 port manifold or a 3 port with a set of shutoff valves. $300 ish the HF ones or cheap ones are ok ish but I've never gotten them to go past 1500 micron. Aka they leak
The gauge will stay at -30 but the trusty micron gauge will be at about 750 to 900 and keep climbing till it's about 1500 then stop.
In order to ensure you have a proper job... 500 micron for 10 minutes or 250 micron for 5 minutes. Then pressure test the system with nitrogen and spray all connections with liquid snot... not soapy water. This is the only way to find leaks. Also the rubber lines.
Make sure you replace all orings with 134a compatible rings (purple or green)
When installing the dryer it's the last thing to go in and ot remove plugs on it one at a time as you hook it up as a slow trickle of nitrogen is flowing.
You need a nitrogen regulator as well.
1 40 tank will do the job but if there is a leak you need a 2nd refill for $50

Weigh in the charge as the compressor is operating. Do a T&P chart to confirm its correct and to adjust it.
Do not over charge as you have already tried many times now.

I never trust a compressor to have the right amount of oil. Dump it and fill yourself. Buy quality parts from our vendors. Do not ebay or rock auto this.

Replace all pressure switches when your doing this as well. Again quality parts.
Usually a diy job is about $1200 including parts and a full days labor if nothing snaps.