The 2015 A/C Thread: Another two years of telling you it's not Freon

The Something Awful Forums > Discussion > Automotive Insanity > The 2015 A/C Thread: Another two years of telling you it's not Freon

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

So, my brother's 1997 Jetta has some strange symptoms. The clutch for the compressor engages fine, as far as we can tell. But watching the pressure gauges suggests otherwise. The high side will climb up to over 350psi a few times then fall down back to 150 and then never go back above 200. The low side pressure dips when the high pressure climbs. The entire time the high side is faltering, the clutch is engaged, so we don't think it's a cutoff switch.

What's going on?

# ¿ Aug 10, 2014 06:17

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# ¿ May 14, 2024 12:07

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

Fortunately, we put some UV dye in it and found a decent mess on one of the lines to the condenser, so it will be opened up pretty soon. I'll check for black death when we do.

# ¿ Aug 13, 2014 02:45

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

I've learned very quickly that low enough to notice usually means more than 12oz low. My sister's truck has a total capacity of 34oz according to the underhood label.

# ¿ Aug 19, 2014 05:21

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

some texas redneck posted:

My car's total capacity is 0.9 lbs, according to the label.

It's barely cooling, so I guess it's -0.1 now?

A pound is sixteen ounces, so it probably has 2oz?

# ¿ Aug 24, 2014 08:06

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

BlackMK4 posted:

My AC died today while driving. There is no leak, the idle changes when I press the AC button on/off, the compressor clutch doesn't engage when pressing the AC button and jumping the pressure switch doesn't kick on the compressor. Is my fuckin compressor dead?

What kind of car do you have, and which pressure switch did you jump?

# ¿ Sep 24, 2014 02:12

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

I need to find a different way to get the dust out of my electronics :catstare:

# ¿ Jan 28, 2015 18:35

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

Motronic posted:

I've not seen a can of R12 or R134a as a duster or air horn in the US in quite some time (even longer for R12 of course, but they did used to use it for that).

These days it's all R152a.

Which is what I'm using as a refrigerant instead of R134a these days on my own beaters...........

I bought this a few weeks ago in south Texas:

# ¿ Jan 28, 2015 19:42

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

Motronic posted:

Wow.....how much was that?

Because it might be cheaper than buying it in refrigerant cans at this point.

$8.99 before sales tax. It's definitely cheaper than going to an auto parts store for it, but only slightly cheaper than wal-mart prices.

# ¿ Jan 28, 2015 22:54

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

This thread really ought to be stickied and/or linked in the OP of the stupid questions thread.

# ¿ Apr 1, 2015 19:48

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

Sentient Data posted:

What kind of price range should I expect a shop to charge for testing a system for leaks? It's currently r12 and I was originally planning to do it myself; getting the refrigerant (legally) is simple enough, ditto the manifold gauge and swapping out whatever parts from rockauto, but I don't currently have anything to make a vacuum, the valves/hookups to pressure test with nitrogen, and the nitrogen itself in this area is only available in giant quantities rather than renting one of the smaller tanks.

The system is old and still holds some of a charge as reported earlier, most likely not enough of one and I obviously need to find out exactly where any potential leaks are before I throw parts at it. I'm assuming what needs to be done is an evacuation of the remaining r12, a fill with nitrogen to test the pressure, adding a dye(d refrigerant?) if the pressure ends up dropping over time, then another evacuation; after that replacing whatever parts, another vacuum, then adding the new r12/oil

e: Or should I go the shortcut route and just try blindly adding more r12? The system's ~27 years old, but I'd imagine the levels wouldn't drop without a place to leak from

Rubber hoses are porous and will slowly leak out any refrigerant in them. For lots of vehicles, that means that some time after ten years or so, you'll notice the ac not working so well. A quick recharge will get them working again. That could be all that is wrong with yours. Or, you could fill it with some UV dyed refrigerant and look with a black light.

# ¿ May 14, 2015 20:48

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

CommieGIR posted:

Are there risks associated with short cycling the system?

Your compressor will fail much sooner than otherwise, and you will get poor cooling.

# ¿ Jun 16, 2015 14:47

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

I can get duster cans of R134a that don't seem to have bitterant in them. Would you be able to smell it in normal use?

# ¿ Jul 6, 2015 15:51

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

Pressures for R134a systems are the same across the board, that's just physics. Use the chart in the OP for reference, it will work for any R134a system.

Can you get a pressure reading when it's refusing to operate? I'd take a wild guess that your evaporator is freezing, which could be from being dirty or not having much airflow due to a dirty cabin air filter, or just undercharged refrigerant.

Get the pressure readings from when it fails before you add any more refrigerant.

# ¿ Jul 11, 2015 20:02

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

PaintVagrant posted:

Is there a way to clean the evaporator?

Cabin air filter is brand new. Ill try getting it to fail, it takes some time though now that I put that can in.

You can't really take the evaporator out to clean it without tearing up your dash and discharging the refrigerant. I've taken a vacuum cleaner to a house's evaporator before to get dust out, but that might not be feasible in a car.

# ¿ Jul 12, 2015 01:04

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

PaintVagrant posted:

Ran the car long enough for it to finally stop blowing cold air.

Ambient: 75

Compressor working:
Low: 35-40
High: 150~

Compressor not working
Low: ~75
High ~100

Compressor short cycled like crazy at idle while compressor was working

Compressor turns off with no real fanfare, the aux fans stay on like the compressor is running. But the pressures change and warm air blows through vents.

Thoughts? I've got another can of refrigerant ready to go

Edit: have not had a chance to get to evap core. Pulled the cabin air filter and felt plumbing, wasn't frozen on the outside or anything.

One thing worth noting is that once the engine has been running, you can't use the ambient air temperature to gauge the average temperature of the refrigerant.

How long was it sitting before you got the "not working" readings? That should equalize pretty quickly with the compressor off.

# ¿ Jul 13, 2015 05:42

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

I know that the high side is a bit harder to read due to having a larger range, but if you had enough difference after 25 minutes to say 75 low 100 high, then you have a blockage in your system somewhere.

# ¿ Jul 13, 2015 14:43

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

CommieGIR posted:

Bought a can tap so I can try my, frankly horrible, idea of using PC Duster to fill the R12 system on my Audi. Gonna go have it vacuumed down and leak tested beforehand by a shop.

Duster cans have R134a or R152, and sometimes an agent to keep people from huffing them.

# ¿ Jul 30, 2015 17:24

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

The performance enhancer will be another gas that alters the performance of the refrigerant. It turns your R134a+oil system into an unknown mixture that you can no longer properly diagnose with pressure and temperature readings, though.

# ¿ Aug 13, 2015 16:15

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

ShittyPostmakerPro posted:

Well, it's had 1atm of air in it for a while, and there is a leak somewhere to the atmosphere. So the desiccant has certainly absorbed some moisture, the question is, is it still good

For the cost of another dryer after you fix all of the leaks, is risking your entire system to acidification worth it?

# ¿ Aug 21, 2015 22:44

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

Motronic posted:

I haven't seen that for years (in the US).

I have seen it in freeze spray cans though (same thing but with an internal straw at and at a much higher price).

I posted a pic of r134a duster that I can get en masse from a local pc parts chain earlier in this thread; it was cheaper than r134a sold as a refrigerant, available in decent quantities, and I live in south Texas.

# ¿ Oct 10, 2015 20:30

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

Shouldn't that trip the low-pressure cutoff?

# ¿ Oct 26, 2015 04:54

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

BrokenKnucklez posted:

Was the compressor running the entire time?

Of course Chrysler makes some goofy rear end algorithm when a simple pressure switch would have done a better job.

Did you go back and start it up again and see if it starts blowing cold after it sat for an hour or so?

Someone probably figured that the warranty repair rate going up with a simulated low pressure cutoff not quite being perfect was cheaper than actually having a low pressure switch in every vehicle. :sigh:

# ¿ Oct 26, 2015 08:44

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

Emptying the system means a new dryer too, right?

# ¿ Oct 28, 2015 08:14

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

Wasabi the J posted:

I think it's if you OPEN the system, it's a new drier. If it's just emptied/vacuumed, you're good as no moisture got into the desiccant; but in this case, he is going to take off the hose, opening the system.

You have to open it to replace a hose, though...

# ¿ Oct 28, 2015 20:42

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

If you have literally zero knowledge of how hosed it was, then I would just save the time and replace all of the compressed gas parts. Every single one. It's the only way to be sure.

# ¿ Nov 11, 2015 07:03

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

CommieGIR posted:

What is your system pressures like? If its low, the compressor won't engage because the pressure switch will prevent it.

Even though this knowledge could conceivably be inferred from the OP, it should have some kind of explicit mention for people that are troubleshooting the electrical side of automotive a/c.

# ¿ Jun 8, 2016 00:27

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

You can't butt-splice the wires together as a temporary fix that won't risk damaging your ac?

# ¿ Jun 17, 2016 19:10

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# ¿ May 14, 2024 12:07

EightBit: Jan 7, 2006; I spent money on this line of text just to make the "Stupid Newbie" go away.

CommieGIR posted:

If the pressures are good and the AC isn't leaking, its not going to do any harm.

If he freezes his coils, a very real possibility when traveling in the swamp-rear end-humid south, he could grenade things. There are lots of vehicles where the only temperature regulation is the blend doors and the low pressure cutoff is necessary to keep the thing from freezing up. If his switch were known bad it would be a different story, but as it stands, you're risking lots of damage when you can take five more minutes to splice the sensor in instead of just jumpering it.

# ¿ Jun 17, 2016 21:18

The Something Awful Forums > Discussion > Automotive Insanity > The 2015 A/C Thread: Another two years of telling you it's not Freon