Automotive Air Conditioning Information Forum (Archives)

rshackleford on Mon May 02, 2011 10:11 AM

Year: 2000
Make: Jeep
Model: Grand Cherokee
Engine Size: 4.7L
Refrigerant Type: R-134a
Ambient Temp: 65
Pressure Low: 26
Pressure High: 170
Country of Origin: United States

Hi,

I'm very new to AC systems but an experienced hobbyist/DIY mechanic.
My Grand Cherokee was blowing hot air out of the AC and I wanted to
try and fix it on my own. I ran the self test for the blend doors and the Passenger
side was fine, the drivers side had too much travel but I was pretty sure I
should be getting cold air at least from te passenger side.

I rented a manifold guage set, vacuum pump and UV LEak detection kit so
I was ready to go.

I put the manifold guages on the system with the engine off and measured
70 psi on both the high and low side.

I then started the car with AC on high and fan blowing on high. The compressor was
cycling on for about 2 secs and off for around 10. Watching the low side pressure
it would turn on at 40 psi and off when it got to 20.

I then shut it off and connected the vacuum pump. I was able to get the vacuum
down to -28 in hg but not to 30.

I let it sit for 1 hour and it held the vacuum.

I then started filling it with R-134. I connected a can to the yellow hose
and then pressed the release valve on th eguage to purge the air from the yellow line.
I then opened the low pressure valve and started filling. The compressor staqrted
staying on longer and now is on all the time.

I was trying to get the pressure to 50/200 but it would only go to 26/165.

Im pretty sure I overfilled it because I put 4 -12oz cans of R-134 in it and afterwards I discovered
it should only take 27oz.

So, what is the best way to get the proper amount of R-134?

Should I bleed it all off, draw and vacuum and start over, or can a bleed off a little at a time
and measure high side pressure to know when I have the right amount?

mk378 on Mon May 02, 2011 10:36 AM

Using a recovery machine, take it all out. Then evacuate to full vacuum and recharge 27 oz by weight. Ordinarily the orifice tube should be checked while it is empty but it appears you have one that is built into the line and can't be non-destructively removed.

The 65F ambient temperature is too low to properly evaluate performance. I would expect low high sides and long off cycles. Pressures looked good considering the conditions. (You don't want to run with a 50 psi low side.) The suction line and accumulator should have been getting cold. If the line is cold but the vents are warm it's an air side problem in the dash.

rshackleford on Mon May 02, 2011 11:40 AM

Quote
Originally posted by: mk378
Using a recovery machine, take it all out.

Lets assume I do not have a recovery machine.

Can I just bleed off the pressure and then start over with pulling a vacuum?


Quote
Originally posted by: mk378
The 65F ambient temperature is too low to properly evaluate performance. I would expect low high sides

What is low high sides?

Quote
Originally posted by: mk378
Pressures looked good considering the conditions. (You don't want to run with a 50 psi low side.)

What low side pressure do I want to run with?

Quote
Originally posted by: mk378
The suction line and accumulator should have been getting cold. If the line is cold but the vents are warm it's an air side problem in the dash.

It is blowing very cold air now from the vents but based on reading on other forums the extra refrigerant could blow seals etc... once we get to summer and it warms up more outside.

I prefer to get the correct amount of refrigerant in the system but it seems like I need to completely drain it before I can get to that point.
Is there a procedure for draining the refrigerant that doesn't start with, take it to a shop or use a recovery system.

Can I just connect an empty can of R-134 to the vellow hose on the manifold and open the low pressure valve to capture the refrig?
Since it has UV dye I would prefer to not have it all over the engine compartment from just releasing it.

HECAT on Mon May 02, 2011 2:11 PM

Quote
Originally posted by: rshackleford

I prefer to get the correct amount of refrigerant in the system but it seems like I need to completely drain it before I can get to that point.

Is there a procedure for draining the refrigerant that doesn't start with, take it to a shop or use a recovery system.

Can I just connect an empty can of R-134 to the vellow hose on the manifold and open the low pressure valve to capture the refrig?

Since it has UV dye I would prefer to not have it all over the engine compartment from just releasing it.

It is illegal to vent refrigerants. No you cannot recover into small cans.

-------------------------


HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

rshackleford on Mon May 02, 2011 2:48 PM

Is there a technical reason why I can capture refrigerant in a can or purely legal?
Im trying to get a real answer.

Often times speed limits are lowered in certain areas solely to generate revenue. If this
refrigerant law is to generate revenue for the AC shops then I have an issue with that.
Im trying to understand why it is illegal to vent refrigerant because from what I read
R-134a is NOT ozone depleting and therefore the perception is the law doesn't increase
safety or protect the environment, the only thing it does is protect margins for AC shops.

Junk yards vent refrierant all the time when they remove compressors, condensors, etc...
Also, R-134a is not ozone depleting, so it seems the only reason for the law is to artificially
provide high margin work for AC shops.

Based on that, is there NO way to get the proper amount of refrigerant in the system without
taking it to an AC shop?


If the answer is no then I guess I will have to vent ALL of the refrigerant, pull a vacumm, and start
over again.

I have read many places that the only way to get the proper refrigerant is to weigh it and
only shops have the equipment to weigh the refrig. Im pretty sure I can just weigh the 12oz
can's before I fill and after and from there accomplish exactly the same thing as a shop would with
expensive equipment.

Im not trying to be argumentitive, but I also have the ability to think for myself and simply saying, its
illegal, doesn't satisfy my curiosity or reasoning.

HECAT on Mon May 02, 2011 4:50 PM

It is a law

HFC's are greenhouse gasses. Spend some time on the EPA site and you will see what the junk yards are being fined for non-compliance.



-------------------------

HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

iceman2555 on Mon May 02, 2011 9:39 PM

No there is no method to insure a correct refrigerant charge without the use of the correct recharge equipment, this involves some method of adequately weighing exactly how much refrigerant is introduced into the vehicle.
The venting of refrigerant is an illegal act...if it were merely to add to AC shop coffers...there you would not have been able to purchase the damn small can at all. The use of small cans is a major contributor to refrigerant leakage. CA just introduced some extremely aggressive pricing for small cans of refrigerant. I, for one, shall be very glad when they are gone. It is impossible to properly recharge a system using small cans and guessing as to the amount of refrigerant is actually being added to the system. Pressures are not indicative of a properly charged system. A properly recharged system will produce certain operational pressures and temperatures...not the other way around.
If you wish to save some serious bucks...a suggestion would be to obtain the services of a good AC shop and have them service the system. Your method is going to produce only one solution...the spending of more cash for a new compressor....and on this vehicle a new condenser....and of course the other parts required to insure a correct repair....so take your pick !!!!
Undercharged systems are the major contributor for compressor failures...both OE units and aftermarket as well. It is necessary for a system to be charged within 1/2 to 1 oz of total system requirements to insure proper lubricant migration for the system. Under charge this system by as much as a couple of ounces and start saving your cash. You are simply not going to achieve this with small cans of refrigerant...no why.....no how.....
Perhaps you should try 'blowing' refrigerant into a small can.....lets..see ambient temp is 65....static pressure in your can with a minimal amount of refrigerant will be.....66.43 psi....your stated low side is 28 psi.....not sure...but it is very difficult to push '28' into 66.43...but what the heck...forget the legal issues....try it.....or if you really have a set....hook it to the....no...will not even go there....hate to see you loose your fingers or hand......why not simply send the cash....have your vehicle serviced properly...save the extra and have a system that functions as expected.
Of course, as stated...vent the stuff....evac and try once more.....one thing is for sure....I bet the results will not change very much......but then you will have spent more cash on refrigerant....opps....wasted more cash on refrigerant.....ahhh...almost forgot something...the boiling point of water at 28 in/hg is 101 degrees....so perhaps your vacuum is not as good as your think....residual moisture in the system will result in acid formulations.....leading to compressor lubricant failure.....thus a new compressor....which probably produced sufficient debris to contaminate your condenser.....oppps...more cash.....perhaps now one begins to understand why I charge the hourly rates I do...it is not WHAT I DO........but WHAT I KNOW HOW TO DO.....
GOOD LUCK !!!!
The current course is headed to disaster.....not a reliable system.


-------------------------
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

rshackleford on Tue May 03, 2011 9:50 AM

The short answer to your question is, if I take it to a shop I don't learn how it works. If I do it myself I get to learn, even from mistakes. I personally can not put a price on knowledge therefore, any financial analysys ends up on the positive for me doing it myself.

I specifically bought this vehicle as a hobby. I do 100% of the mechanical work myself and have literally saved $1000's of dollars already.

I do not know what you charge, but I can buy one heck of alot of $15 cans of R-134 for the $1000 the shops around me want to repair an ac system.

I already have a brand new compressor, accumulator, o-ring kit etc... laying on the garage floor ready to install. I have less than $200 in all the parts. Additionally as far as I am concerned I have already fixed the original problem, the AC blows ice cold air where as three days ago it did not.

On other forums I have talked to people who at least claim, as yourself, to be a professional AC certified person and they have said they have succesfully charged and topped off systems for many years using only pressure gauges, ambient temperature and small cans.

Lastly, I don't know in what world you guys live in, but in my world I would much prefer the EPA be solving problems like massive oil spills in the Gulf rather than chasing a hobbyist mechanic releasing a few oz of R-134 in his garage on a weekend.

Let me know where you live and Ill move there. It seems so wonderful I would probably be happy to pay extra for AC service. We can't even swim in Lake Michigan anytime it rains because Milwaukee's sewage treatment system releases raw sewage, again I would much prefer the EPA worry about that.

HECAT on Tue May 03, 2011 5:12 PM

You can get professional advice here, if you wish to listen. It will rarely include short cuts that can lead to an early system failure, or instructions that require breaking the law. It is preferred to fix it right and comply with regulation.

-------------------------

HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

rshackleford on Tue May 03, 2011 10:21 PM

Quote
Originally posted by: HECAT
You can get professional advice here, if you wish to listen. It will rarely include short cuts that can lead to an early system failure, or instructions that require breaking the law. It is preferred to fix it right and comply with regulation.

Im all about fixing it right. But rarely does "fixing it right" mean to blindly take it to a shop and hand them the keys to my vehicle and then stand behind a wall with a sign that says "No Customers allowed beyond this sign". I personally am much more meticulous and caring for all of my vehicles than any other person would ever be and I always "fix it right".

If someone on this forum can give me a real justification for taking the vehicle to a shop I will gladly follow that line of reasoning until it quits making sense. Im never would have made it in the military because I'm cursed with the ability to think for myself.

So far, HECAT, the extent or your advice has been brief and geared more towards legal matters rather than technical issues regarding AC systems.

I can think for myself and evaluate the law based on my own morals. Not all laws make sense and some require that people break them to bring fairness to society. A few examples are laws that prevented women from voting or require blacks to sit on the back of the bus. Others are just plain unreasonable and are expected to be broken, for instance, speeding laws. HECAT, based on your avatar, I'd be willing to bet you have exceeded the speed limit a couple times on public highways, possibly even today. Id go so far as to say you have probably broken speeding laws more times this week than I have released R-134.

So, I'm more than willing to listen to technical facts related to my questions regarding Automotive AC systems. As far as dictating morals, Ill pass on listening to that. Killing people = bad; releasing a little R-134= not so bad.

TRB on Tue May 03, 2011 11:52 PM

You can do as you please. But a site designed to provide auto a/c information is not going to suggest the release of refrigerants period.

Simple answer to the questions. Fix the leak if there is one. Pull a vacuum before charging. Charge back to the OEM specs. Charging by pressures can lead to so many other issues and a shorten life of the system.

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

rshackleford on Wed May 04, 2011 11:05 AM

Let me go about this another way.

1) Assuming I am starting with a system with no refrigerant and if each can is 12oz by weight and a system requires exactly 24oz can't I just put two cans in the system? Wouldn't this fill the system to the proper amount? and if the requirement is not an even increment of 12oz, can't I weigh the can before I start and as Im filling and therefore get extremely close to the exact amount?

2) what is the minimum amount of work I can have performed by a shop? is it possible to have them just evacuate the system? no pulling a vacuum or refilling. And since they get to keep the refrigerant shouldn't this at least be free if not them paying me for the refrig they get to keep and reuse?

That should accomplish my goal of learning to work on the system and satisfy the legal requirements of not releasing refrigerant.

TRB on Wed May 04, 2011 11:11 AM

24 ounces is 24 ounces.

A shop will charge you to reclaim refrigerant and normally keep it also. You have man hours, shop equipment, $4k for a R & R machine. Plus in our shop we run a test check purity of refrigerant also before it's even hooked to our equipment.

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

mk378 on Wed May 04, 2011 11:24 AM

Some of the oil change chains offer to reclaim and / or charge R-134a. That is the only A/C thing they do. I wouldn't have them do anything to my car other than take refrigerant out, but it's hard to mess that up.

I didn't say you had to go to a shop, there's nothing stopping you from buying the proper tools and obtaining the knowledge necessary to do it yourself. As you noticed, that investment will pay for itself in just a few uses. For example buying a 30 lb cylinder of R-134a is less than half the price of buying the same amount in small cans (40 cans). You can buy a scale with that money and then be equipped to make an exact charge every time with no waste.

Edited: Wed May 04, 2011 at 11:26 AM by mk378

Karl Hofmann on Wed May 04, 2011 12:39 PM

Quote
Originally posted by: rshackleford




Im not trying to be argumentitive, but I also have the ability to think for myself and simply saying, its

illegal, doesn't satisfy my curiosity or reasoning.


Ok then, how about this reason..... I don't much want to breathe the R134a that you dump into the air that we all breathe..



-------------------------
Never knock on deaths door... Ring the doorbell and run away, death really hates that!

rshackleford on Wed May 04, 2011 1:51 PM

Quote
Originally posted by: Karl Hofmann
Quote
Originally posted by: rshackleford








Im not trying to be argumentitive, but I also have the ability to think for myself and simply saying, its



illegal, doesn't satisfy my curiosity or reasoning.





Ok then, how about this reason..... I don't much want to breathe the R134a that you dump into the air that we all breathe..

Thats a funny comment. If you were really concerned about what you breathe, why have you made 2992 posts on a website who's sole purpose is to help people make it more comfortable to ride in cars. I know quite a bit about pollution and green house gases and driving a car is much worse than me releasing a couple oz of refrigerant. If you truly care about the environment, get off this site and buy a bicycle. And, quit telling people how to fix their AC because the car generates more pollution and greenhouse gas when the engine is under additional load from a compressor. Tell everyone to roll down their windows.

You can't have it both ways. Either you are environmentally concious or you are not. Don't pick and choose to be friendly to the environment only when it benefits you financially. It give the appearance of being cheap and shallow.

rshackleford on Wed May 04, 2011 1:57 PM

Quote
Originally posted by: TRB
24 ounces is 24 ounces.

So then from your response, contrary to the other replies, I do NOT need expensive scales and equipment to
make sure I have the proper amount of refrigerant in the system. I need to measure the weight
of refrigerant I put in rather than just looking at the pressures, correct??


Quote
Originally posted by: TRB
24 ounces is 24 ounces.
A shop will charge you to reclaim refrigerant and normally keep it also. You have man hours, shop equipment, $4k for a R & R machine. Plus in our shop we run a test check purity of refrigerant also before it's even hooked to our equipment.

How do you perform that check and what if it fails?

TRB on Wed May 04, 2011 2:05 PM

With equipment to perform such tasks. If it does not pass the purity level. We say we can't work on your vehicle. Take it back top whomever put the contaminated refrigerant in your system. If it has a sealer in it depending on type. The customer is inform by opening the system every component could be damaged and need a replacement. You need to be able to weight 24 ounces. As I stated the equipment to reclaim refrigerant is 4K US. Refrigerant I identifier is 1K and a sealer analyzer is about $200.00.

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

rshackleford on Wed May 04, 2011 2:48 PM

Quote
Originally posted by: TRB
With equipment to perform such tasks. If it does not pass the purity level. We say we can't work on your vehicle. Take it back top whomever put the contaminated refrigerant in your system. If it has a sealer in it depending on type. The customer is inform by opening the system every component could be damaged and need a replacement. You need to be able to weight 24 ounces. As I stated the equipment to reclaim refrigerant is 4K US. Refrigerant I identifier is 1K and a sealer analyzer is about $200.00.

How could every component in the system be damaged simply by opening it?

rshackleford on Wed May 04, 2011 2:56 PM

Quote
Originally posted by: TRB
You need to be able to weight 24 ounces.
Thats easy, 2 X 12oz equals 24 ounces. I don't need a scale for that.
This is exactly why it appears that you only want to obfuscate your answers.
I keep getting replies that suggest I need expensive equipment to weigh 24oz. I do not.
Why does every keep implying that it requires significant training and expensive equipment to weigh 24oz?
Can't the answer simply be, take the system to a cheap shop and have them remove existing refrigerant.
Then put exactly 2 - 12oz cans of refrig in and you are good to go.
I just do not understand why you guys keep trying to avoid the obvious answer except
to protect your high margin business.

rshackleford on Wed May 04, 2011 3:00 PM

Quote
Originally posted by: TRB
With equipment to perform such tasks. If it does not pass the purity level. We say we can't work on your vehicle.

Since Im pretty sure my refrigerant has some level of contaniments most shops will
refuse to work on it. In this case the AC industry has given me 2 options;
1) vent the gas myself or..
2) rip the entire AC system out of the car and accpet the fact I will never have AC

You are not making any sense.

TRB on Wed May 04, 2011 3:01 PM

Where have I said you need an expensive piece of equipment to weight something?

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

robs on Wed May 04, 2011 3:08 PM

Any "experienced hobbyist/DIY mechanic" should have a great understanding on what they are working on. I believe you can benefit greatly from purchasing the AUTO AC REPAIR MANUAL that goes into detail on the auto a/c systems and understanding the functions for each component and how to test/repair/diagnose your own system, along with many different tools professionals use. Understanding the A/C system will make you understand the answers people are giving you.

rshackleford on Wed May 04, 2011 3:19 PM

Quote
Originally posted by: TRB
Where have I said you need an expensive piece of equipment to weight something?

You are correct. You did not say that you need expensive equipment to weight something. But you also didn't say, "You are correct,
if the system requires 24oz, you should be fine with just putting two 12oz cans in the system.

TRB on Wed May 04, 2011 3:28 PM

Thanks because using 12 ounce cans can lead to not getting all of the refrigerant out of the can. So did you get 11.5 or 11.9 or of the can?

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com