A/C recharge

[greenskeeper]

Do the A/C recharge kits work? Should I take the car to a shop?

My A/C hasn't worked in 2yrs or so. I don't mind but other passengers (wife, infant son) have made noises about the lack of A/C

 

[JonsTDI]

I've found they work if you don't have a major leak. Get one with a brass adapter that screw onto the can. Also make sure it says it comes with the leak stopping crap. If you put 2 cans in and it gets cold, but then a week later it's not cold anymore you are best off going to a shop. If you want to diagnose it yourself you get a can of stuff that has an IR dye in it. Since A/C fluid boils around 10F, it will never drip and show a leak. The IR stuff will stay liquid and you use a blacklight to find the leak. That way you know it's from the A/C and not oil or coolant. Hope that helps.

 

[pawel]

Do the A/C recharge kits work? Should I take the car to a shop?

My A/C hasn't worked in 2yrs or so. I don't mind but other passengers (wife, infant son) have made noises about the lack of A/C

First, you should find and fix the leak. Next, you should use a vacuum pump to extract air and moisture in the system and then use a gauge set to charge the system. And do not forget about oil charge, which should be first thing you do while charging the system.

that's what I be doing this weekend to our "baby vehicle"

 

[compu_85]

Never, ever add any "leak sealer" to your car's air conditioning system! Read the back of the can carefully!

Also, don't blindly add R134a. Get a gauge set and see what's going on. It could be an electrical problem.

-Jason

 

[Lug_Nut]

The gas will evaporate / boil away. The oil remains behind. There is no need to put more oil in on top of the oil that has been there right along.

Use a gauge, add die and freon until the unit starts working. The pressure will be low, and not too cold, but in a day or two if it has leaked at all it will allow you to pinpoint the location of the gas loss.
Then fix it.
And then have it properly (usally means professionally) evacuated and refilled.

 

[sfierz]

This has been the experience on my 96 Passat TDI. I have to top off the A/c with R134 usually at the beginning of summer but then it will last all the way through summer into fall and winter. I know there is a small leak somewhere and that should be professionally fixed, but with half a can or something used throughout the year getting me back into the cold air, I don't worry about it too much. Also, yes to having an accurate gauge on there so you don't over or under fill. I believe mine varies between 25-40 psi on the low side. When it gets into the 20s it's too low and doesn't cool well.

Oh, but I pretty much only use the straight R134, no leak stop.

I've found they work if you don't have a major leak. Get one with a brass adapter that screw onto the can. Also make sure it says it comes with the leak stopping crap. If you put 2 cans in and it gets cold, but then a week later it's not cold anymore you are best off going to a shop. If you want to diagnose it yourself you get a can of stuff that has an IR dye in it. Since A/C fluid boils around 10F, it will never drip and show a leak. The IR stuff will stay liquid and you use a blacklight to find the leak. That way you know it's from the A/C and not oil or coolant. Hope that helps.

 

[rotarykid]

I went to college for refrigeration and can say that sealer / stop leak charges often fix a leaking system if used correctly . If misused/overused they can lead to unending problems .

There are plenty of Good "Stop leak" charges that work well if the leak is dry seal related . On most systems the leak is related to a dry seal from lack of use .

The thing about "stop leak" charges never use but one . If that one doesn't stop the leak don't charge with another one . That is where people get into trouble clogging things up .

I've seen "super seal" charges fix compressor seals that were leaking . I've also seen these "super seal" charges fix a leaking evaporator coil .

On HFCs ( R-134a ) I really hate the stuff . It's a very poor refrigerant that is not very efficient . It was used in the US because the company that owned the patients had the most money when a the switch was made away from CFCs in the early 90s .

HC blends ( Hydrocarbon blends like Red Tek & Enviro-Safe to name a couple ) are what I've been using for close to 20 years in all the systems I work on . The refrigerant that is planned to replace HFC-134a next year when it is removed from the market is a HC blend . Red-Tek is the HC Blend I use when I work on a car's ac system . Red-Tek & Enviro-Safe both have a really good "stop leak" charge along with a "super seal" charge . Both work very well when used properly .

And before someone chimes in on the flammability of HC blends ,

All refrigerants are flammable when pressurized & misced with refrigerant oil in an ac system , CFCs & HFCs included ..... Most HC blends have a much higher flash point (~1,400*F) , about twice the temp of that of HFC's flashpoint of ( ~700*F) when misced with oil and pressurized in an ac system . The entire flammability thing was a scare tactic used by the HFC producers . The end of next year when HFC-134a is replaced with a HC blend all this will be a mute point .

 

[rotarykid]

The bleed down pressure for an HFC (R-134a) system is ~38-40 to 55 psig . Most HFC systems will not cool if the bleed down pressure is below 38 psig . Any lower and you are below the bleed down pressure valve opening pressure in the evaporator . CFC systems had a bleed down pressure that ranged from 25 to 40 psig which is one of the many reasons HFCs were useless in a CFC spec system as a replacement without heavy modifications .

Also unlike a CFC system that would operate if slightly undercharged or overcharged an HFC system will not function( cool at all ) if undercharged or overcharged . So you should never try to charge an HFC filled system without gauges . The range of the bleed down cooling window is so small due to the inefficiency of HFCs .

A HFC spec/filled system being slightly undercharged or overcharged can lead to system damage & failure . And once you have an over charged HFC system high pressure damage can occur quickly to the ac system . And that damage can lead to a complete inability of the HFC filled system to ever cool again properly .

 

[thebigarniedog]

Do the A/C recharge kits work? Should I take the car to a shop?

My A/C hasn't worked in 2yrs or so. I don't mind but other passengers (wife, infant son) have made noises about the lack of A/C

Tim McCarver (baseball announcer for all you non-baseball fans) summed it up best: The actual Count (balls/strikes on a batter) isn't as important as how you got there. The same applies to your a/c system. The key question is how you got to this point.

If the system was previously discharged for the replacement of a component or any of the other countless reasons then a recharge kit by itself won't help you. If you have a component problem, then obviously a recharge kit isn't the problem. If it just gradually stopped being cold over the years then yes buy a recharge kit with gauges and you will probably be fine.

Now I will ad this caveat that applies to this specific OP Greengeeker. From your other postings (over the years) I am quite confident that you know what you are doing on these cars. I am adding the below link for others and I mean no slight to you:


http://faculty.ccp.edu/faculty/dreed/Campingart/jettatech/acwork/index.htm

 

[hevster1]

If a system has been open or inop for 2 years (or a day for that matter) because of a leak the receiver/drier needs replacement. Replace it last and then immediately evacuate the system for at least 1 hour and preferably more with a quality vacuum pump. Remember, you are removing moisture and air and small amounts of moisture can compromise efficiency.

I do not EVER recommend stop leak as I have never had any success with it. It is a band-aid at best. Do it once and do it right.

As far as R-134 being a crappy refrigerant; compared to R-12 yes. However I can and do get vent temps rivalling R-12 systems with proper evacuations and charging systems to no more than max. The system works great with no problems. Why bother with a hydrocarbon setup?

 

[Sbeghan]

IME, these cars cool very well and don't need a propane setup. I've also found that propane will leak through the hose rubber. Few months later and all your refrigerant is gone - just use R134a.

 

[rotarykid]

IME, these cars cool very well and don't need a propane setup. I've also found that propane will leak through the hose rubber. Few months later and all your refrigerant is gone - just use R134a.

Are you just making this crap up ????? I never said one word about using propane HC blends are not propane !!!!

Sorry but you don't know W@# your talking about when it comes to o-rings . The acids produced form HFCs & PAG oil are the most destructive mix there is when it comes to o-rings , expansion valves & compressors . HFCs and PAG oil also produce a destructive clogging up powder inside of your ac system over time leading to failure . No such issue with HC blends .

HC blends like Red Tek HC-12a or Enviro-Safe require only 6 ozs to replace 16 ozs of the HFC-134a charge , 18 ozs of CFC-12 so the volume required for operation is much lower reducing system wear . A fully charged system that requires say 35-40 ozs of HFC-134a requires only 13-15 ozs of HC-12a .

HC blends operate @ less than 1/2 the head pressure ( 250-300 psig max compared the same system with HFC-134a operating above 500+ psig ) on the high side reducing compressor , expansion valve & o-ring strain & wear .

Lower head pressures mean less energy used to produce similar cooling , less fuel used during high ambient heat cooling . Less compressor wear during cooling , less stress on o-rings , less strain on hoses & the condenser and less stain on the electrical system .

HC blends are as much as 5-7 times more efficient in cooling . Where a fully charged HFC-134a systems can struggle to reach 40*F under high ambient temps . That same system with a HC blend charge can easily cool down into the mid 10s*F ( 15-18*F ) . Lower evaporator temps means quicker cooling from high heat events .

I really don't care what refrigerant you use in your ac system . I never use HFC refrigerants as they are useless compared to HC blends . HFC-134a is being withdrawn from the world market at the end of next year . It is being replaced with a blend that has HCs in the mix . This new mix is a drop in replacement just as HC blends are today in all ac systems .

HC blends are 100 % miscible with all refrigerant oils . HFCs are not compatible with other oils and are easily contaminated with moisture leading poor cooling .

HC blends don't have the moisture contamination issues of HFCs so will cool in a system that has water contamination when HFCs will not .

I'm just sharing the knowledge I have from over 32 years of home & auto ac repair . You can listen to what I know or not I could care less ....But if you quote inaccurate garbage about HC blends like calling them propane I will respond with the real facts .

 

[Steel]

I say we switch back to ammonia. Then you'll REALLY know when you have a leak!!

/i kid

 

[Sbeghan]

rotary, I was using propane as a synonym for an HC blend because the common HC blends are mixtures of propane and butane.

I tried a propane/butane blend. No leaks before I evacuated the system. I refilled and could smell the lemony scent used as a leak detector afterwards. I ended up changing hoses that were fine because I could smell the scent through the rubber hoses at the front of the car (and it would lose its refrigerant charge after a month). Even with new hoses it was still leaking!

I refilled with HFC R12a and it stopped leaking and never had a problem for years.

In short: the HC blend was leaking through the rubber hose, not the o-rings.

 

[rotarykid]

rotary, I was using propane as a synonym for an HC blend because the common HC blends are mixtures of propane and butane.

I tried a propane/butane blend. No leaks before I evacuated the system. I refilled and could smell the lemony scent used as a leak detector afterwords. I ended up changing hoses that were fine because I could smell the scent through the rubber hoses at the front of the car (and it would lose its refrigerant charge after a month). Even with new hoses it was still leaking!

I refilled with HFC R134a and it stopped leaking and never had a problem for years.

In short: the HC blend was leaking through the rubber hose, not the o-rings.

I've seen what you describe several times in HFC-134a spec'ed systems . And due to the lack of knowledge available in the US I'm not surprised of your experience . The hoses you replaced I'm sure there was nothing wrong with them , here is what I'm sure you experienced ;

What I bet was happening was the overpressure valve was opening and expelling part of the charge when the sun's heat made the charge expand in the system . The expansion rate of HC blends is many times that of HFC-134a , 6 ozs of an HC blend ~ 16 ozs of HFC-134a . As I stated you only need a small % of the charge HFC required to cool .

What I have seen happen is in order to get a HC blend to bleed down in the evaporator within the HFC spec range of 38-40 to 55 psig the system must be overfilled . What happens is the system will stay charged until in the heat of the sun the HC blend expands overfilling the system . The overcharge which is required to reach HFC bleed down specs expands in the heat to the point that it bleeds out of the overpressure valve . When the temps are normalized again the charge is too low to reach the higher HFC spec bleed down pressures so no cooling .

If the system bleed down spec was lowered by modifying the bleed down opening pressures to 25 to 38 psig the remaining charge would cool many times better than the origional HFC-134a charge . I've made this change to many HFC-134a systems . On a modified stock HFC system as much as 20*F drop in cooling temp can be documented .

If the system is filled to capacity with a 100 % HC blend the bleed down pressure will be 25-38 psig . In order to switch an HFC spec system to a 100 % HC blend charge the bleed down spec pressure must be modified to operate in the lower pressure range .

What many people do is add a can of HFC-134a to a HC blend charge which changes the bleed down characteristics to more match HFC-134a spec . I've seen this bring the evaporator pressure bleed down spec to match the design spec of a HFC system . And the plus is the mix of refrigerants retains the much higher efficiency , as much as a 20 *F drop in cooling temp of the HC blend . On modified and mixed systems I've seen cooling air temps drop from struggling to reach 40-45*F in ~90-95*F ambient suddenly able to reach mid 10s*F ( 15-18*F ) in the same ambient .

A note for anyone that cares it's illegal for an individual to mix refrigerants which is stupid . A stupid law that really makes no sense today because all refrigerants are blends of some sort , even many of the HFC-134a refill charges are blends of some sort ( Usually an HC blend of some sort ) . What mixing does is raise the bleed down pressure to within spec of how the system is set up without requiring the system volume of the charge being overfilled .

The other thing people do is disable the bleed down overpressure valve , I don't recommend that one . A HC blend filled system operates @ much lower pressures so a disabled overpressure valve would likely not cause any problems . But if it were ever to fill the system with HFC-134a again the valve would have to be enabled again to prevent explosive lose of pressure . HC blend charge pressures max out short of 350-400 psig on the high side while 550 to 600+ psig can easily be reached on the high side with an HFC charge with a condenser fan failure .

In the US there seems to be a "head in the sand" attitude when it comes to refrigeration . I've learned what I know about HC blends from working on freezers , home ac , auto and farm equipment ac CFC spec systems .

I was taught about CFCs and HFCs in college , much of what they told us in school I've learned was not based on reality but was political bullsh!t . I learned first hand what different mixes of refrigerants can do and what they can't . Many of the things I've learned first hand were expressly forbidden from what I learned in college , again political bullsh!t . Today HC blends are the norm of/in all refrigerants on the market today since CFCs are being completely banned .

HC blends are environmentally friendly and the only refrigerants that can preform close to what chlorine based refrigerants could do . HFC-134a is being replaced with a HC blended refrigerant the end of next year if today's mandates are carried through on .

 

[greenskeeper]

Ok so I vacuumed out the system then refilled with a can of recharge and oil. Ran the A/C for about 20 min and did not seems to get cold. It is putting out a little cooler air but not like when it was working good.

As far as I can tell the compressor is engaging. I will check today what the pressure is at and if I lost any (leak). The chart on the can said 55psi for 90 degrees ambient temp which is what I set it at.

 

[hevster1]

Ok so I vacuumed out the system then refilled with a can of recharge and oil. Ran the A/C for about 20 min and did not seems to get cold. It is putting out a little cooler air but not like when it was working good.

As far as I can tell the compressor is engaging. I will check today what the pressure is at and if I lost any (leak). The chart on the can said 55psi for 90 degrees ambient temp which is what I set it at.

So what are the guage readings at 1500 rpm?

 

[sfierz]

Ok, I'm no expert, but two things here. 55psi seems a little high assuming this is the low side reading. Also, a fully evacuated system would seem to take more than a 12oz can of R134a. Somethings not right here. It seems our cars run pretty cold with low side @30-40 psi at 90F at idle.

 

[greenskeeper]

So what are the guage readings at 1500 rpm?

didn't read it at 1500rpm. This was at idle. 55psi was what the chart said for 90F ambient temp.

The A/C should blow cold air even at idle, correct?

 

[sfierz]

Yes, it should blow cold at idle. Perhaps the low side pressure is too high for this system. What does the specification in the engine compartment say? Sometimes it lists pressures.

 

[greenskeeper]

nothing listed in the engine compartment. What could cause it to only take a little more than 1/2 bottle of refrig and read 55psi?

 

[hevster1]

There are a lot of assumptions here. First off let me ask, are you using conventional gauges or the ones that come on the cans of R-134 sometimes? If the latter is the case, go out and buy gauges or bring it to someone who knows a/c. Second, have you added multiple cans of sealant at any point? Third, how long did you evacuate it for and did your gauges read a vacuum (see question 1)? Last how much oil did you add and how did you add it?

At idle it should blow cold but with it at about 1500-2000 rpm it will give you the readings needed to make a proper diagnosis. Without having both a decent high and low pressure gauge it is going to be very hard if not impossible to determine the cause without a guess. Guessing costs YOU money. For example if you have 55psi on both high and low side and your compressor is turning I would tell you the compressor is bad and the system is somewhat undercharged.

 

[rotarykid]

The 38-40 to 55 psig is right out of the refrigerant install/refill manual for HFC-134a . 55 psig is the bleed down starting point on the high end of the bleed down scale ( hotter side ) , 38-40 psig is at the low end of the scale ( cooler side ) . In a properly operating and filled HFC system the pressure should start @ ~ 55 psig . As the system removes the heat from the car the low side pressure should drop down to the mid 40s psig range .

If the system is under filled you will see readings below 35 psig along with little if any cooling . A reason for a high reading of ~55 psig can be a moisture clogged dryer/receiver not allowing for bleed down . The system can build higher pressures to force the charge through the slightly clogged dryer/receiver on it's way to the evaporator. Another reason for a high pressure reading on the low side is a system being overfilled . An overfilled HFC system will not cool and can lead to an overpressure on the high side . It is very easy to reach the overfilled point on an HFC filled system . The most common reason for an overfill is a system that was filled not under a complete vacuum . As long as the system can get into that range of 40-55 psig the system can cool . But if you are stuck in the higher end range of that scale the system can less efficient during extreme heat shock .

HFC filled systems require a very strong desiccant , much more than a CFC or HC blend filled system to remove the water from the system . HFC filled systems must be filled under a vacuum to reach the proper fill & pressures . Any free water in the system decreases cooling and reacts with the PAG oil to produce a contaminating acid . Once the desiccant reaches the saturation of moisture point the problems begin . Any ac system that has set open to air for any time must have the dryer/receiver replaced before refill for it to function properly .

 

[sfierz]

Glad to have some pros chime in here. I believe I was on the right track. Some other problem in system or overfill. I've had a lingering underfill on mine (small leak) but finally got it to where it should be this summer. Much better cooling now.

 

[greenskeeper]

So I looked at my system again.

I have 50psi on the low side when the A/C is not in use.

When I turn on the A/C is drops to 20-25psi.

Is the pressure reading taken while in use or static? ambient temp is 75F

I have no leaks since it has held pressure for 10 months now.

The compressor clutch kicks in, the cooling fans turn on.

Do I need to add more refrigerant to bring up the psi in the system?

 

[compu_85]

You take a pressure reading with the system operating. You have a leak. Add some more 134A with UV dye in it (be sure NOT to add leak sealer!!!!!!!!!). Then see if you can locate the leak

-J

 

[greenskeeper]

goes back up to 50psi when turned off

should probably get gauges for the high side.

I think the compressor is not up to par

 

[DanG144]

Yes, you need to know the high side pressure as well.

50 psig when turned off corresponds to only 55 deg F. Is it that cool there?

If the gauge is correct and the temperatures are higher than 70F, then you have no liquid refrigerant left in the system, only gas. Indicating a leak.

 

[greenskeeper]

o-ring fail

going to replace all o-rings and the dryer/accumlator

see what happens then.

from my research the system should take 28oz of ref and 3.9oz of oil if completely dry.

 

[rotarykid]

o-ring fail

going to replace all o-rings and the dryer/accumulator

see what happens then.

from my research the system should take 28oz of ref and 3.9oz of oil if completely dry.

Make sure you soak the new o-rings in refrigerant oil, the same oil you use to fill the system! A cap full of oil to completely submerse and soak the o-rings is a good idea. And a ample supply oil to coat the threads of each connection is also a good idea.

I would also use a oil/seal protector/stop leak charge for the first fill from vacuum because this will disperse it more fully throughout the system. Wal-Mart has a big blue can of this mix that can be gotten for the mid ~$25 range. On a system that has lost it's charge many times, there are weak points in the system like dry o-rings. A charge like this can prevent a long process of chasing down new issues like leaks from dried out o-rings that no longer seal properly once charge has been lost. Take my word from close to 35 years now of work on ac systems, working on a car ac system can be an unending nightmare. The older the system is the longer that nightmare can be during repair. And many times when you start to fix known issues the more new issues can start to appear just from opening up the system.

On a older ac system where I failed to use the above advise I have spent weeks and $$$$$ on refrigerant trying to chase down all the issues that seem to come. The older the system, car is the more likely an ac repair can turn into a money and time pit...........