ComStar A/C Zero-Leak, Permanent "Stop Leak" for A/C Systems, Seals Leaks Instantly, Non-Hardening, Polymer-Free, Eco-Friendly, Made in USA, 4 Ounces (90-700)

This worked great for me to plug a leaky fitting that connected a rubber elbow to an aluminum hard line. I was dreading having to evacuate the freon, introduce a sealer, then pull a vacuum and repush freon and a little compressor oil. (I could see that some compressor oil was lost in the engine bay.)I bought a $35 pressure oil and dye injector kit here on Amazon and put two ounces of this into my system with it, which enabled me to seal and re-oil all in one shot. Basically the sealant is blended into a PAG oil base. So far so good, and I saved myself a lot of DIY time or costly labor on an 18-year-old car that I plan to get rid of in two years anyway.I've used a couple of the other "quick-shot" tube kits that you can connect to your refrigerant line and push with the refrigerant top-up. That stuff has a different formulation and is just not enough volume to plug more significant leaks. This requires more work and equipment (pressure oil injector) on a charged system, but the results are superior.I'm a believer in this stuff, and I'll be using it from now on on my older cars, refrigerators and home a/c systems as there is little to lose at that point if it doesn't work. I just had my two home evaporator coils replaced at a "steal" price of $3,600, and I wish I had seen this first!

Highly recommend this stop leak additive as an Auto AC technician have installed additive in many vehicles with evaporator leaks and have great success.

This product worked for me, it fixed what appeared to be a large leak on the A/C evaporator core on my 2008 Trailblazer. It was my last ditch effort before having to chose between paying over $1,000 in labor + parts, or to spend 2+ days and approx. $300 in parts replacing the evap core myself. No A/C while sitting in traffic at temperatures consistently above 88F year-round (rarely dipping below 70F even during "winter") here in South Florida is not really an option. Like in most vehicles, to replace the evap core on a Trailblazer you have to remove the entire dashboard, center console, steering wheel, radio, sound amplifier, and all sorts of wiring and connectors just to be able to get to and remove the plastic enclosure that houses the evaporator core, definitively not a short weekend project unless you are a professional who does this for a living.Long story short, none of the other highly rated stop-leak products I tried before Comstar A/C Zero Leak worked. I recharged the A/C system three times (4-8Oz or more of the stop-leak product plus pure R134-a refrigerant) each time using a different product and following the manufacturer's directions. I was careful to use only products that claimed not to ruin your compressor, accumulator, orifice tube, or to clog your A/C system, every time, the A/C would go from freezing cold right after recharging it back to blowing hot air within 2-3 days max. This SUV is a retired undercover unit I bought at a Police surplus auction, I'm pretty sure their maintenance crew tried to fix the issue before decommissioning the vehicle, everything else on it works just fine.Two months ago I purchased this product (Comstar A/C Zero Leak, 4 oz.) and an A/C repair kit that includes a vacuum pump, manifold gauges, vacuum pump oil, hoses, and accessories ( https://www.amazon.com/gp/product/B077PY6NHR/ref=ppx_yo_dt_b_asin_title_o01_s01?ie=UTF8&psc=1 ), I also purchased 4 Oz PAG oil and enough pure R134-a refrigerant to refill the system, all for less than $170. I took the SUV to my mechanic to have the A/C evacuated using the proper equipment ( most A/C shops do this for free around here), then I added a approximately 2 ounces of this product by pouring it directly into the hose connected to the low pressure port before opening any valves, and proceeded to recharge the system with some PAG oil (2 Oz in my case) and the amount of R134-a as specified in the owner's manual. SUCCESS!It's been two months since I did this, and my A/C remains so cold that I rarely have to bring the controls above the minimum fan speed on this sweltering Florida summer. I use a bluetooth OBD II reader with a mobile app to keep an eye on my A/C internal pressure (reported by the high pressure sensor) along with the engine and transmission temperatures, my A/C high pressure hasn't dropped at all during this time. I don't know if this will keep my A/C working months or years, but so far so good.

Unfortunately didn't work for me. And it appears this brand doesn't offer a money back guarantee like other stop leak products. I would recommend buying another product, based on it doesn't work... And they don't stand behind their product.

...have not noticed any issues as of yet. Need to complete a vacuum test to verify effectiveness.