Where's likely suspect for R134A leak?

07-04-2007, 06:23 PM
'99 GMC Sonoma (Chev S 10), 4.3 L V-6, 5-spd standard, one-owner, low miles (under 25K), regularly maintained, all-original, never wrecked. Not trying to sell it, but I could use help re where to start looking/testing for a very small, slow A/C refrigerant leak. In 6/06 it wasn't blowing cold so added a pound of 134A. Gauged out fine hi and low. Fixed, right? I never had added any refrigerant before, though I don't use the A/C much. Now it's a year later and the refrigerant's just low enough, again, that it isn't blowing cold. Compressor, lines & accumulator look clean as a pin, no oil anywhere. Good serpentine belt. Compressor runs good, line connections look sound. Before I go charging on this system again I feel like I oughtta try to find the leak. An A/C tech told me they lose refrigerant if they're not run occasionally during the winter. OK, I'll accept that, but I still think there's a leak somewhere. So far as I know it didn't lose any refrigerant during at least the first 4-5 years of service. Ideas? Thanks for reading.

07-04-2007, 06:36 PM
Very simple. Factory refrigerant has a dye in it. Take a black light to it and it'll show up greenish. Check all the fitings and tubes.

07-05-2007, 08:48 AM
As said a leak dye kit.
Also watch for oily spots.
Check for old leaks first first and then wash off all old stuff.
Then you will need a full charge to bring pressure up to full pressure for some to leak.
Recharge system and add a can of leak dye.
Do not use the one hose one gauge stop leak death kits from the jip joints.
Drive and start rechecking.
As your mechanic said.
Some systems will hold in hot weather and leak off in winter.
For hard to find leaks always use the yellow glasses with the leak kit.
Check lines and hoses and fittings.
Check front and rear and middle of compressor.
Check AC rad condenser good
And check evaporator bottom and inside fins.
R-134a will always leak to the bottom so always look on the under side of everything.
Good luck on the leak hunting.hunting.

07-05-2007, 08:05 PM
As MT said - a lot - don't use the death kits. I did though and it worked great though. I figure if it didn't work it'd all leak out the a/c wouldn't work and I'd only be out $20. MT has always given very good advise and this is no different. The choice however is yours.

07-06-2007, 09:15 AM
I have to agree I bought the Sub Zero Synthetic R134a Leak and lube recharge and it worked great, although I did have my cousin do it using high and low pressure guages, basically the correct tools as he does HVAC for a living.

07-06-2007, 12:03 PM
Here is just a little info on blends and other stuff.

http://www.autoacforum.com/messagevi..._MSGDB TABLE=

This one shows one blowing up and almost killing the dude.



There is no direct replacement for R12 no matter what anyone tells you. Unique fittings and a label is required with all SNAP refrigerants replacing R12. Vehicles without a HPCO switch are required to have one if an alternative is used.






Choosing and Using Alternative Refrigerants for Motor Vehicle Air ConditioningOzone Protection Hotline (800) 296-1996 May 1, 2001Changes from the October 14, 1999 version: added one refrigerant; other editorial changes. BackgroundScientists worldwide have concluded that CFC-12 and other chlorofluorocarbons deplete the ozone layer. As a result, over 150 countries have signed a treaty, called the Montreal Protocol, to protect the earth's ozone layer. In the US, the Protocol is implemented by the Clean Air Act, and regulations issued under the Act ended the production of CFC-12 for air conditioning and refrigeration uses on December 31, 1995. CFC-12 (also known by the trade name Freon) was widely used in air conditioners for automobiles and trucks for over 30 years. While new vehicles no longer use CFC-12, most vehicles built before 1994 still require its use for servicing. As a result, 30 million cars or more may need conversions to use an alternative refrigerant should the air conditioning develop a leak after CFC-12 is no longer available.Note: there are several other relevant fact sheets available online and through our hotline. Significant New Alternatives Policy (SNAP)In 1994, EPA established the SNAP Program to review alternatives to ozone-depleting substances like CFC-12. Under the authority of the 1990 Clean Air Act (CAA), EPA examines new substitutes for their ozone-depleting, global warming, flammability, and toxicity characteristics. EPA has determined that several refrigerants are acceptable for use as CFC-12 replacements in motor vehicle air conditioning systems, subject to certain use conditions. This fact sheet lists the use conditions in detail and provides information about the current crop of refrigerants. It is important to understand the meaning of "acceptable subject to use conditions." EPA believes such refrigerants, when used in accordance with the conditions, are safer for human health and the environment than CFC-12. This designation does not mean that the refrigerant will work in any specific system, nor does it mean that the refrigerant is perfectly safe regardless of how it is used. Finally, note that EPA does not approve or endorse any one refrigerant that is acceptable subject to use conditions over others also in that category. Note also that EPA does not test refrigerants under the SNAP process. Rather, we review information submitted to us by manufacturers and various independent testing laboratories. Therefore, it is important to discuss any new refrigerant with your vehicle dealer and shop technician before deciding to use it, and in particular to determine what effect using a new refrigerant will have on your warranty. Before choosing a new refrigerant, you should also consider whether it is readily and widely available, and your technician should consider the cost of buying recovery equipment for blends or recovery/recycling equipment for HFC-134a. Additional considerations about purchasing CFC-12 substitutes can be found in EPA's fact sheet titled "Questions to Ask Before You Purchase an Alternative Refrigerant."Definition of "Motor Vehicle Air Conditioning"Under the SNAP program, the motor vehicle air conditioning (MVAC) end-use includes all forms of air conditioning that provide cooling to the passenger compartments in moving vehicles. This definition includes both MVACs, defined under the section 609 regulations at 40 CFR 82.32, and MVAC-like equipment, defined under the section 608 regulations at 40 CFR 82.152. EPA regulations issued under sections 608 and 609 of the Clean Air Act distinguish between MVACs and MVAC-like equipment for purposes of refrigerant recycling and handling. EPA includes both in the SNAP MVAC end-use and has relied on this definition since the original SNAP rule of March 18, 1994 (59 FR 13044). All use conditions, unacceptability findings, and other regulatory actions for this end-use apply equally to on-road vehicles, such as automobiles and trucks, and to off-road vehicles, such as tractors, combines, construction, mining equipment, boats, planes, and trains.Misleading Use of "Drop-in" to Describe RefrigerantsMany companies use the term "drop-in" to mean that a substitute refrigerant will perform identically to CFC-12, that no modifications need to be made to the system, and that the alternative can be used alone or mixed with CFC-12. However, EPA believes the term confuses and obscures several important regulatory and technical points. First, charging one refrigerant into a system before extracting the old refrigerant is a violation of the SNAP use conditions and is, therefore, illegal. Second, certain components may be required by law, such as hoses and compressor shutoff switches. If these components are not present, they must be installed. See the section below on use conditions for more information on these points. Third, it is impossible to test a refrigerant in the thousands of air conditioning systems in existence to demonstrate identical performance. In addition, system performance is strongly affected by outside temperature, humidity, driving conditions, etc., and it is impossible to ensure equal performance under all of these conditions. Finally, it is very difficult to demonstrate that system components will last as long as they would have if CFC-12 were used. For all of these reasons, EPA does not use the term "drop-in" to describe any alternative refrigerant.Use ConditionsUnder the SNAP rule, each new refrigerant must be used in accordance with the conditions listed below. If you choose to use an alternative, make sure the service shop meets these requirements and that it has dedicated recovery equipment for blends or recovery/recycling equipment for HFC-134a. UNIQUE FITTINGS: Each new refrigerant must be used with a unique set of fittings to prevent the accidental mixing of different refrigerants. These fittings are attachment points on the car itself, on all recovery and recycling equipment, on can taps and other charging equipment, and on all refrigerant containers. If the car is being retrofitted, any service fittings not converted to the new refrigerant must be permanently disabled. Unique fittings help protect the consumer by ensuring that only one type of refrigerant is

used in each car. They also help protect the purity of the recycled supply of CFC-12, which means it will last longer, so fewer retrofits will be necessary nationwide. The list of fittings is available in an EPA fact sheet titled "Fitting Sizes and Label Colors for Motor Vehicle Refrigerants." Applicability to Manifold Gauges and Refrigerant IdentifiersManifold gauges allow technicians to diagnose system problems and to charge, recover, and/or recycle refrigerant. A standard fitting may be used at the end of the hoses attached to the manifold gauges, but unique fittings must be permanently attached at the ends of the hoses that attach to vehicle air conditioning systems and recovery or recycling equipment. Similarly, refrigerant identifiers may be used with multiple refrigerants. The connection between the identifier or similar service equipment and the service hose may be standardized and work with multiple hoses. For each refrigerant, however, the user must attach a hose to the identifier that has a fitting unique to that refrigerant permanently attached to the end going to the vehicle. Adapters for one refrigerant may not be attached to end 2 and then removed and replaced with the fitting for a different refrigerant. The guiding principle is that once attached to a hose, the fitting is permanent and is not removed.LABELS: Whether a car is originally designed to use a new refrigerant or is retrofitted, the technician must apply a detailed label giving specific information about the alternative. The label's background color is chosen by the manufacturer to be unique, and the label colors for each refrigerant are listed in an EPA fact sheet titled "Fitting Sizes and Label Colors for Motor Vehicle Refrigerants." The label shows: · the name and address of the technician and the company performing the retrofit; · the date of the retrofit; · the trade name, charge amount, and, when applicable, the ASHRAE numerical designation of the refrigerant; · the type, manufacturer, and amount of lubricant used; and · if the refrigerant is or contains an ozone-depleting substance, the phrase "ozone depleter" This label covers up information about the old refrigerant, and provides valuable details on the alternative and how it was used. It also tells the owner who performed the retrofit.REMOVE ORIGINAL REFRIGERANT: The original CFC-12 must be removed from the system prior to charging with the new refrigerant. This procedure will prevent the contamination of one refrigerant with another. Refrigerants mixed within a system probably won't work and could damage the system. As mentioned above, this requirement means that no alternative can be used as a "drop-in." BARRIER HOSES: HCFC-22, a component in some blends, can seep out through traditional hoses. Therefore, when using these blends, the technician must ensure that new, less permeable "barrier" hoses are used. These hoses must be installed if the system currently uses old, non-barrier hoses.. The table of refrigerants below notes this additional requirement where appropriate. COMPRESSOR SHUTOFF SWITCH: Some systems have a device that automatically releases refrigerant to the atmosphere to prevent extremely high pressures. When retrofitting any system with such a device to use a new refrigerant, the technician must also install a high-pressure shutoff switch. This switch will prevent the compressor from increasing the pressure to the point where the refrigerant is vented. Alternative RefrigerantsThe table below summarizes the following information about refrigerants reviewed under EPA's SNAP program for use in motor vehicle air conditioning systems. Note that "air conditioning" means cooling vehicle passenger compartments, not cargo areas, so refrigeration units on trucks and rail cars are not covered by this list. If your browser cannot display tables, please call our Hotline at 800-296-1996 to receive a free copy of this fact sheet in the mail or by fax. The title is "Choosing and Using Alternative Refrigerants for Motor Vehicle Air Conditioning".· Name: Many refrigerants are sold under various names. All known trade names are listed, separated by slashes. · Status: o acceptable subject to use conditions: May be used in any car or truck air conditioning system, provided the technician meets the conditions described above. Note that EPA cannot guarantee that any refrigerant will work in a specific system. o unacceptable: Illegal to use as a substitute for CFC-12 in motor vehicle air conditioners. o proposed acceptable subject to use conditions: May be used legally. EPA will accept public comment on these refrigerants and then make a final ruling. There is no formal EPA position until then, and it is inappropriate for advertising to imply that EPA has found the product acceptable. o not submitted: Illegal to use or sell as a substitute for CFC-12 in motor vehicle air conditioning systems. · Date of ruling: The date either a final rule or a proposed listing was published in the Federal Register. Note that proposed listings are not final and may change because of public comment. · Manufacturer name and contact phone number: Call for more information on testing, performance, system compatibility, etc. · Composition: Every refrigerant other than HFC-134a is a blend of two or more components. For More InformationEPA's Stratospheric Ozone Protection Hotline, at 800-296-1996, distributes numerous fact sheets and brochures. The following fact sheets discuss various issues related to motor vehicle air conditioning and ozone depletion.· Fitting Sizes and Label Colors for Motor Vehicle Refrigerants· Questions to Ask Before You Purchase an Alternative Refrigerant· The Facts Behind the Phaseout (ozone depletion science)· Qs & As on HC-12a, OZ-12, and Other Flammable Refrigerants· Qs & As on Ozone-Depleting Refrigerants and Their Alternatives Motor Vehicle Air Conditioning Substitutes for CFC-12 Reviewed Under EPA's SNAP Program as of March 29, 2006Acceptable Subject to Use Conditions (2)
Name (1) Date Manufacturer Components
HCFC-22 HCFC-124 HCFC-142b HFC-134a Butane(R-600)(3) Isobutane(R-600a)(3) HFC-227ea
HFC-134a 3/18/94 Several - - - 100 - - -
FRIGCFR-12 6/13/95 IntercoolDistributionl800-555-1442 - 39 - 59 2 - -
Free Zone/RB-276(4) 5/22/96 Hi Tech Refrigerants, LLC800-530-4805 - - 19 79 - - -
Ikon-12 5/22/96 Ikon Corp.601-868-0755 Composition claimed as confidential business information
R-406A/GHG(5) 10/16/96 People's Welding800-382-9006 55 - 41 - - 4 -
GHG-HP (5) 10/16/96 People's Welding800-382-9006 65 - 31 - - 4 -
GHG-X4/Autofrost/Chill-It (5) 10/16/96 People's Welding800-382-9006McMullen Oil Products800- 669-5730 51 28.5 16.5 - - 4 -
Hot Shot/Kar Kool (5) 10/16/96 ICOR800-357-4062 50 39 9.5 - - 1.5 -
Freeze 12 10/16/96 Technical Chemical800-527-0885 - - 20 80 - - -
GHG-X5 (5) 6/3/97 People's Welding800-382-9006 41 - 15 - - 4 40
SP34E 12/18/00 Solpower888-289-8866 Composition claimed as confidential business information
RS-24 12/20/02 Refrigerant Products Ltd Composition claimed as confidential business information
R-420A 3/29/06 RMS of Georgia - - 12 88 - - -
Unacceptable Substitutes (2)
Name (1) Date Manufacturer Reason
OZ-12® 3/18/94 OZ Technology Flammable blend of hydrocarbons; insufficient data to demonstrate safety
R-176 3/18/94 Arctic Chill Contains CFC-12, which is inappropriate in a CFC-12 substitute
HC-12a® 6/13/95 OZ Technology Flammable blend of hydrocarbons; insufficient data to demonstrate safety
Duracool 12a 6/13/95 Duracool Limited This blend is identical to HC-12a® in composition but is manufactured by a different company
R-405A 6/13/95 Greencool Contains a perfluorocarbon, which has extremely high global warming potential and lifetime
1. Many refrigerants, including R-401A (made by DuPont), R-401B (DuPont), R-409A (Elf Atochem), Care 30 (Calor Gas), Adak-29/Adak-12 (TACIP Int'l), MT-31 (Millenia Tech), and ES-12R (Intervest), have not been submitted for review in motor vehicle air conditioning, and it is therefore illegal to use these refrigerants in such systems as an alternative to CFC-12.2. See text for details on legality of use according to status o Acceptable Subject to Use Conditionsregarding fittings, labeling, no drop-in, and compressor shutoff switches. o Unacceptable; illegal for use as a CFC-12 substitute in motor vehicle air conditioners 3. Although some blends contain flammable components, all blends that are Acceptable Subject to Use Conditions are nonflammable as blended.4. Freezone contains 2% of a lubricant5. HCFC-22 content results in an additional use condition: must be used with barrier hoses

07-06-2007, 09:57 PM
You sure are long winded! Do you have kids? I'd hate to be them!:grinyes::grinyes:

07-06-2007, 10:30 PM
r134 can stay in your system for years. you have a leak and on blazers its usually the comp. The thing to do is replace the schrader valves on the high and low side. while the lines are off, poor a shot of ac die from napa and then recharge. you dont need any special glasses, just a bright light and not blind. most shops rip cust off on ac. in a week check for any leaks.

07-08-2007, 05:10 PM
Thanks to all. I do recall last year, when the A/C tech with the gauges read the system and added the can of 134A, when he pulled his charger fitting loose from one of the Schrader valves (the one on the tube? I forget), it hissed just long enough before closing up that he and I both noticed it. He said he thought it seemed "OK," which I took to mean it might have seated back tight or it might have a tiny steady leak. So what you said about those valves kinda reinforces my suspicion about how/where the refrigerant escaped. Kind of a trial & error thing, like a tire with good tread, no nails or cuts in it, but it loses a little air over a couple weeks driving. The compressor functions fine, quiet, clutch works as it should, no oil behind or underneath it, so it's not my first suspect.

07-21-2007, 11:40 PM
sounds like you found your leak at the schr. valves. I see techs all the time put caps back on and not check to see if they are leaking. spray some soap and water on the valve, it will bubble if it is leaking.:smokin:

07-23-2007, 07:25 AM
Good 'ol soapy water spray - that's a good tip. I'll do it. Weather's been unusually cool for TX last couple weeks, lots of rain. So I haven't really needed the A/C. Though I have used the defroster - compressor seems to be doing its job. Thanks.

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