Automotive Air Conditioning Information Forum (Archives)

joepeterson56 on Thu July 11, 2013 12:00 AM

Year: 2009
Make: Hyundai
Model: Elantra
Engine Size: 2.0
Refrigerant Type: 134a
Ambient Temp: 84
Pressure Low: 63
Pressure High: 112
Country of Origin: United States

A/C suddenly stopped blowing cold air. Put cheap aftermarket charging hose w/gauge on it first, said charged, showed blue zone for ok. Not satisfied w that, I put my mastercool gauge on & got some bizarre readings.

1st reading, engine & comp off - gauge valves closed, reading L=63 H=112.

2nd reading, engine on A/C not on yet - opened low side valve on gauge, reading L=25 H=125. Pressure Line too hot to touch/hold, not temp hot or cold to touch on low line.

After checking all connections fuses etc, took readings again, L=26.5 H=0. Thought that reading was strange, removed gauges made sure lines on it were purged, valves closed, hooked back up reading 0/0. Started engine & A/C, reading 0/0. WTF? My gauges crap the bed or what?

Put cheap aftermarket hose back on, gauge still says charged/ok, but showed a slightly lower pressure then the first time I checked it with that one. Totally frustrated I call dealer & ask questions, figuring it must be a blockage in the system, so it may be covered under warranty due to a part failure, so I bring it in tomorrow 7/11.

Service dept tells me that MOST cars USUALLY need an Evacuation & Recharge every 4 to 5 years. Anyone ever hear of this before? If so, is that the usual Life Expectancy of 134a?

fix_it on Thu July 11, 2013 5:57 AM

Life expectancy of R134a? Forever. Really. It doesn't get used up in the AC system. It just goes round and round. Those Walmart gauges are pretty much junk. Can't really trust that. Also can't go by pressure alone to know if you are charged properly.

1st reading: The system had been operating and the pressures haven't yet equalized. Nothing strange here.

2nd reading: You opened the valve on the gauge manifold? I'd guess that now you have just vented all your R134a to the atmosphere. That explains the 0/0 reading you saw next.

Now you will need to properly evacuate and recharge before you can begin to figure out what was really wrong before you started.

NickD on Thu July 11, 2013 7:45 AM

Recovery of the existing refrigerant is common to measure how much is in there. Do add some additional to bring it to proper level, then put if all back again. Has nothing to do with the life of the refrigerant.

But appears to me, playing with that can of crap, you may have contaminated your system, not only with that leak stuff, but also with air and moisture. Are you going to hold your dealer responsible for that?

If he is smart, he will know you played with it. Happens to me every once in awhile, can only say, if you want me to repair it, its going to cost you extra, or just leave.

mk378 on Thu July 11, 2013 9:51 AM

First some manifold 101. The valves on the manifold remain closed at all times except to add or remove stuff through the center (yellow) hose. The gauges are connected directly to the red and blue hoses before the valves so they always show the pressure in the hoses even with the valves closed. Like fix_it said, opening a valve without anything connected to the yellow hose is likely to let the refrigerant escape.

If your manifold's service port couplers have knobs on the top, the knob moves the valve pin up and down. First be sure the knob is fully counterclockwise so the pin is retracted, then pull up the locking ring and couple onto the car fitting. Once it's locked on, turn the knob clockwise to extend the pin, which will open the shrader valve in the car and let refrigerant flow to the gauge. Uncoupling is of course the opposite, turn knob ccw first to close the shrader valve, then uncouple.

Reading 125 / 25, no cooling, discharge hose gets very hot, all point to a serious undercharge-- i.e. it had leaked out. If you really did open the system to the air and vent it to a zero pressure (it's not just measurement error from using the couplers improperly), air has likely moved in so it needs to be evacuated first before recharging. Expect it to continue to leak, so put in some UV dye or check immediately with an electronic leak detector and find the leak.

Preventative maintenance on an auto A/C system is all external, such as checking the belt and cleaning the air side of the heat exchangers. There is no need to do anything with the refrigerant as long as it is working properly. Refrigerant doesn't wear out, it only needs replacing if it has leaked away.

If you take it to the dealer now, they see zero pressure and don't know anything else, with any luck they will just find the leak (seems that there is a pretty big one, to go from OK to no cooling in a week) and fix it under warranty for you.

Edited: Thu July 11, 2013 at 10:00 AM by mk378

Cussboy on Thu July 11, 2013 3:33 PM

Quote
Originally posted by: joepeterson56
Service dept tells me that MOST cars USUALLY need an Evacuation & Recharge every 4 to 5 years. Anyone ever hear of this before? If so, is that the usual Life Expectancy of 134a?

What total BS !!! If the system cools you, then it's OK. Sure, check the belt condition, whether the condenser fins are free of debris and clean, check any cabin air filter. But Evacuation and Recharge? Ridiculous.

Another huge moneymaker for some dealers and mechanics is nitrogen into tires. Regular air is already 79% nitrogen. Even if one evacuated a tire of air and then filled with nitrogen, guess would be to get maybe 94% nitrogen. In my years, I've never seen a tire dry-rot from the inside....

Last year Mrs. Cusser had her 2005 Yukon in at dealer for sunroof repair (wouldn't close), and dealer spent more effort "checking" stuff out to try to get extra business. One thing they stated was that it needed new radiator hoses, as hers were original; pretty interesting since I had replaced the lower radiator hose a month before with a Gates hose, which still had the Gates tag on it, plus a non-factory worm-type hose clamp, when I replaced the leaky water pump. I wonder if the dealer did a lok-see on CarQuest to assess the Yukon's condition. By the way, three visits to the dealer, and the sunroof still doesn't always close.

Edited: Thu July 11, 2013 at 3:37 PM by Cussboy

TRB on Thu July 11, 2013 3:43 PM

I run nitrogen in my bicycle tires. Which I run tubeless and swear it allows the sealer to last longer and not ball up. Plus it sounds cool compared to the other kids on the block.


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Contact: ACKits.com

pippo on Thu July 11, 2013 8:05 PM

Evacuate/recharge every 5 years.....even I know thats dumb advice. Nitrogen? Dealer told me its better cuz its biger molecule, so leaks out slower. Sheesh, the difference in the 2 is sooo small- anyone who took (and passed with a B or better) high school chem knows that nitrogen is right next to oxygen- size difference is so small. I told her no.

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beware of the arrival

NickD on Fri July 12, 2013 5:53 AM

My assumption with all this crap on the market for refrigerants and with AC problems, would be to recover, check for impurities, and learn how much was in there. Sure GMtech and iceman would go along with this.

Seems like other assumptions, is the system is working perfectly well, but told to change the refrigerant anyway, because it worn out. This is a bit crazy.

Nitrogen is always used in large aircraft tires for a number of good reasons as opposed to air. But not talking low pressure tires in automotive with maybe a mere 1,000 pound load and driving at 55 mph. Super high speed, extreme pressures, with many tons of load per tire.

For one thing, nitrogen can be viewed as treated air, removes all the oxygen and moisture, former is combustible with super hot temperatures, later will boil at a mere 212*F causing severe pressure changes. Former is also an oxidizing agent cause corrosion in valves an aluminum. For smaller airports, nitrogen is more convenient to use when you need 500 psi of pressure, try finding an air compressor that can give those kinds of pressures. Moisture also freezes in super subzero temperature aircraft experience. Nitrogen is an inert gas, air is not.

Know what you are talking about before posting.

iceman2555 on Fri July 12, 2013 1:21 PM

Quote
What total BS !!! If the system cools you, then it's OK. Sure, check the belt condition, whether the condenser fins are free of debris and clean, check any cabin air filter. But Evacuation and Recharge? Ridiculous.

Actually this is not total BS. A vast majority of over the road trucking companies will service the AC system every 100k miles. This involves the removal of the refrigerant, R/D replacement and a recharge. This service maintains refrigerant levels and extends compressor life.
Simply because a vehicle is cooling does not mean the system is fully charged. In some circumstances an undercharged system may actually cool better or as well as a fully charged system. As the recharge rate tends to decrease in volume the amount of 'undercharge' prior to compressor damage tends to become much less. Lubricant migration maybe reduced significantly by undercharges that may not produce loose of cabin cooling.

A Rec/Recharge every two three years is a low cost alternative to very expense AC repairs. Changes in the AC system are changing the type and cost of most compressor replacements. It is not often to see vehicles that require total system replacements when a compressor fails. A bit of preventative maintenance could help prevent this.

Although refrigerant does not have a life expectancy, AC systems do often leak....and at some point, system damage occurs....keeping the system properly charged....engine cooling systems at OE specs will prevent system damage. The number of OE failures that I evaluate each year is astronomical.....the vast majority of them are totally dry inside.....this is the result of lose of lubricant migration due to lose of sufficient refrigerant to maintain flow.

The statement the dealer made was not BS....should be considered a 'preventative' maintenance procedure. But most will not adhere to this procedure....hey....it's cooling what could go wrong. Thankfully this is the normal mind set....keeps me working....



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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

Cussboy on Fri July 12, 2013 10:10 PM

I still say "never trouble trouble until trouble troubles you". Not quite the same as a radiator coolant flush, or ATF change....

Leggie on Sun July 14, 2013 4:06 PM

Quote

Service dept tells me that MOST cars USUALLY need an Evacuation & Recharge every 4 to 5 years. Anyone ever hear of this before? If so, is that the usual Life Expectancy of 134a?

Interpretation of temperatures and pressures are the means of charging for refrigeration and HVAC, but not cars. Charging by pressures and observations require much more skills than charging by weight. It is also not a guarantee that you will get a perfect charge level in an MVAC.

Modern machines are quite automated so that required skill levels for technicians can be lowered.

Recovering and monitoring the amount recovered is an effective means of evaluating the rate of leak. Auto ACs inevitably leak to varying extents due to effusion through hoses and compressor shaft seal even if all piping connections are perfect. Home ACs and refrigerators can only leak if there is a hole somewhere due to imperfect joints or damaged components as everything is hermetically sealed.

iceman2555 on Sun July 14, 2013 5:52 PM

It is totally understandable...not to trouble trouble....but when AC trouble arrives....it normally arrives with a very severe repair order also. The process of simply extending the possible repair by a bi annual service far out weights the downside. With the very short charge of todays cars, a slight leak can often result in early demise of the compressor. Consider that the cost factor to replace this unit and complete the system service may exceed several thousand dollars......well...nuff said. You're gonna pay the piper...one way or the other. Save the money...service the AC as one would any other system in the vehicle.

All this being said...they typical auto owner does not even think of AC system service....not until the system fails or stops cooling......mmmm....is that the sound of dollars hitting the cash register....why yes it is....thank you very much Mr. Customer....remember, when an offer was made to service your system for $@#%.00. and you felt you were 'being taken advantage of'.

Thankfully systems are not serviced as they should be...thus our sales tend to increase each year........gotta love it.

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

powerflite on Mon July 15, 2013 12:29 PM

Contrary to a statement above, Nitogen is not an inert gas. It reacts with a number of elements.

mk378 on Mon July 15, 2013 12:39 PM

Nitrogen won't react with the materials and conditions found inside a tire though so it can be considered "inert" for that application. The gases in the last column of the periodic table have been found to engage in chemical reactions under very extreme conditions, so they are not properly called "inert" any more either. They are now known as the "noble" gases.

NickD on Tue July 16, 2013 8:00 AM

I can go along with iceman on this issue, but not the R-134a, but that PAG exposed to high temperatures that will break down.

There was a time when refrigerants were isolated from the lubricants in MVAC, should have stuck with that concept. And mixing the fluids with the refrigerant has only one powerful effect, reduced cooling.

Can you imagine using an air compressor that mixes oil with air? Same principle, except you will be spray painting with oil.

Still say they should advertise, if you want problems, we have problems. Lots of them.