How to tell if A/C refrigerant is low? Steps to recharge?

For the small amount of refrigerant an automobile a/c unit uses it is always best and most accurate to just weigh in the exact factory charge and limit the length of hoses on your manifold set (only use the low side connection while charging). Every time you hook up a set of gauges it robs a small amount of refrigerant from the system until you finally screw the charge up enough to affect performance. The days of the receivers with sight glasses made it easy to "top off" a charge. But with a system holding as little as a pound and a half of refrigerant, a couple ounces can cost you a significant amount of performance. Overcharging causes compressor flooding which can severely damage the compressor by washing the compressor oil out of the compressor. The accumulator is a band-aid to ensure 100% vapor returns to the compressor. Since the oil is not held separate from the refrigerant, a little oil is always traveling through the system and if a TXV is used it lubricates the valve. But with a proper charge, clean coils, and a clean blower wheel, the oil will return to the compressor to maintain the proper level. Adding too much oil is very bad for the life of the compressor as it is in a motor vehicle.

The tough part for most do it yourself guys is having the equipment to legally extract the existing charge, purge and leak check with nitrogen, fix the leak, and then pull a less than 400 micron vacuum to ensure the system is totally clean and leak free. Because if you are adding refrigerant you have a leak which should be located and dealt with. I am not a big fan of the dyes. JMHO

 

+1

And many DIY kits also include a stop-leak. Many shops won't touch your system if they are aware that you have stop-leak in the system because it can screw up their recovery equipment, and if your system is ever opened with stop-leak in it, your compressor will need to be replaced because the stop-leak will solidify.

 

BTW, we're replying to a thread that's been dead for 30 months.

 

RRRiiiggghhhttt.

So I don't recommend this but........

When i was younger I would take a can of a/c juice and take a pointy knife and pop a very, very, very, very small hole in the top center. Wait until the sound of the flowing air just about stops then widen the hole a very, very, very, very small amount. Do this about 8-10 times in a row going very, very, very, very slowly at this. It takes about 5 mins of work. When you finally get get it to a point the hole is the size of a BB you can pour out in to a metal bowl.

If you don't do those steps properly the can could blow up on you. So don't try it.

Then the fun begins. You can put things in the fluid and freeze them. Like bugs flowers or what ever might provide some entertainment. Then take said items and throw on wall or ground and they shatter.

Now the only reason I bring this up is well I am still alive and have not died from pulmonary edema.

So basically I am calling BS on you. I have done this over 5 times in my life and am just fine.

Keep in mind the shit will freeze the shit out of you if it gets on your skin. But stupid is stupid does.

Don't forget the safety glasses kids.





So with all the young and dumb talk done I would recommend getting a can with refrigerant only and a gauge. Not the stuff with all the oils and other crap. Because you might only use a 1/4 of the can and the system already has plenty of oil in it. An just follow the directions on how to do it. It is general very easy to do just start the truck and put the a/c on max and high fan. Put the can on the gauge and attach the gauge to the a/c system and read the gauge if any is needed add until gauge reads good then done. Easy as pie.

 

R134 is directly toxic only if ignited.
In it's normal state, the only danger is the same as of inhaling helium balloons or nitrous.

 

Freon burned = Phosgene Gas = Highly toxic.

R134A burned = hydrogen fluoride gas = Also Toxic

 

First used in 1915 by the Germans phosgene gas was a very effective chemical weapon. Don't play around with any refrigerant. It can blind you, or even kill you if inhaled.

 

In reference to the bolded text, you are incorrect. Gauges can show you if there is a problem with a compressor, if there is a restriction in the system, AND if you know how to properly read the gauges and reference, you can actually tell if a system has a full charge, or is low, or even over charged. I do it all the time in my shop. And yes, I also have to correct Evac and recharge machine as well. Also, the minimum vacuum time is only 15 minutes at 29 inches of mercury.

You never want to add any refrigerant until you verify for sure that some has been lost. I have seen 8-10 year old cars and trucks that had no perceptible loss, and overcharging by even 1/4 of a pound WILL adversely affect performance.

Hmmmm. I won't call BS since I wasn't there, but I do find it difficult to buy that one since R12 boils at -21.7°F. Even a tiny hole would vent R12 into the atmosphere until every bit of it evaporated. Not unless when you did this you were living in Alaska and it was 22 below at the time...lol.

 

Nope works just fine in a 90 degree summer. That is long as you do it right. And not it does not instantly vaporize. Unless if you poured it out it would. It basically looks and acts like Liquid Nitrogen just not as cold.

 

I agree, I was taught to put my gauges on only if other tests showed it necessary. Every time you hook up your gauges you rob some of the refrigerant charge. And on units holding less than a couple pounds of gas, ounces can cost you performance.

Since R-12 boils @ -21.7F, unless the ambient air is colder it will vaporize, period. We used a lot of R-11 in Centrifugal units and it boils @ 74.79F, so on a cold day you could pour it. We are talking about units that hold hundreds of pounds of refrigerant.

 

So for those of you that THINK they understand science lets hear how you explain this. If the liquid nitrogen in these video boils at -321 F then why is he able to pour it? I already know the answer so explain it to every one else. By the way its science backed up with facts you if you don't know what you are talking about then don't guess. Cause it makes you look stupid.

Again I have done this multiple times with refrigerant and i am still alive and well. And no I would not put my hand in the refrigerant like in the video. Just other things.



http://www.youtube.com/watch?v=gjsMV1MglA4

http://www.youtube.com/watch?v=_9MI5BvOmLk

 

pretty easy to do. did it on the gf's car....i'm going to top mine off in the spring

 

Amazing stuff. Thanks for all the good stuff.

Just picked up a can of R134a and noticed they charged me $10 for a deposit. The empty can needs to be returned within 90 days with the original receipt.

Our revenue generators - oh sorry - I meant lawmakers are wonderful. Let me get this straight. You need to return the bottle but only for 90 days. I am certain they used the data of the ozone depleting refrigerants of the past to create the required hysteria. I suppose the threat goes away after 90 days of purchase.

When I did my masters I studied recycling programs (cause I love the idea without all the politics that surrounds it). The CA CRV program was originally intended to incentivise the general population to reduce the amount of stuff we 'stuff' into landfills by 50% and then they would end the CRV... fast forward, we have far surpassed that goal and we still tax the poor people with this tax. I see this $10 tax as one in the same.

The EPA is going to do great things for us in the future. I just hope they change their name so as to create a little truth in advertising.

 

I have to say, I loved this quote:

 

I also was thinking my truck was slightly low in freon. So I took a visit to my local ac shop and told him it just didn't feel cold as it due to be. ( maybe because it was 97 degree outside). He ended up pulling all the old freon and oil out and holding a good vacuum for around 20 min to determine there was no leaks. He then filled with new freon and oil and determined that he removed just as much as he put back in. NO LEAKS. He told me that is the only way to make absolute sure it is not over filled, ( which could end very bad). He also told me as long as there is no leaks in the system that the freon will last the length of the vehicle. So the conclusion of the story is that it was a waste of a 20 $ bill and I was OCD.

 

Does anyone know the location of the low pressure a/c port is located at on a 05-11 4.0 V6?

 

Right next to the dipstick

 

I thought r12 was really bad for the ozon layer
I used to work for a ac company
my boss would call the guys who just vented into the atmosphere and do work as blow and go guys
Haha could also apply to other professions

 

Cool, thats what i thought. Sometimes has a blue cap. Thanks

 

I just recharged mine this morning with a can of AC Pro. Quite simple.

I just tried to get the pressure barely into the green arc on the gauge at 29-30 PSI while the compressor clutch was engaged. I took my time and released it in 5 second bursts.

My 2009 is nearly 12 years old and sat a bit. The AC was working but it wasn’t really cold like it was when it was new. The AC Pro says it includes an additive designed to help the seals do a better job. If this doesn’t work I’ll take it to a professional, but so far it’s working great.