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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / May 2008Pressurize A/C to find leaks?
I've decided to take one more stab at fixing my A/C in my '93 Mazda 626... My problem right now is that, even after replacing the blown high pressure line, that the system won't hold a vacuum. What I want to do is apply a bit of pressure to the system and use a soap solution to try and identify where the leak is occurring. Sounds straight forward, but I'm not sure how much pressure I can safely apply to the low pressure fitting. How much pressure can I apply here? Will this do what I need? >I've decided to take one more stab at fixing my A/C in my '93 Mazda 626... > [quoted text clipped - 7 lines] > >How much pressure can I apply here? Will this do what I need? You can easily put 50psi in the lines. Low pressure side is around 40 when in operation while high side will be 200 or more. Have you already replaced the o-rings that you just replaced? Seems most likely that one of those got nicked or rolled under upon assembly. If you can't find the leak Second shot would be to put in 1 can of 134a and take it to an a/c shop with a sniffer. They can tell you pretty quickly what is leaking. Steve B. >>I've decided to take one more stab at fixing my A/C in my '93 Mazda 626... >> [quoted text clipped - 16 lines] > 134a and take it to an a/c shop with a sniffer. They can tell you > pretty quickly what is leaking. Thanks folks! This is what I figured, but wanted to hear a few more opinions before I broke something. I'm planning on checking all the joints this time, instead of only the ones that I needed to loosen to do my repairs. > I've decided to take one more stab at fixing my A/C in my '93 Mazda 626... > [quoted text clipped - 7 lines] > > How much pressure can I apply here? Will this do what I need? What do you propose to pressurize with? >> I've decided to take one more stab at fixing my A/C in my '93 Mazda >> 626... >> What I want to do is apply a bit of pressure to the system and use a soap >> solution to try and identify where the leak is occurring. Sounds straight >> forward, but I'm not sure how much pressure I can safely apply to the low >> pressure fitting. >> >> How much pressure can I apply here? Will this do what I need? > What do you propose to pressurize with? Dried air from an air compressor. "aarcuda69062" <nonelson@sbcglobal.net> wrote in message news:nonelson- > What do you propose to pressurize with? Air should be okay, assuming that he has lost most of the pressure already AND that he repairs and evacuates the system. Of course, if a small leak is present in some hidden place, evaporator coil, etc., he may never spot it with soap bubbles. The best way to find tiny leaks is with an electronic sniffer, but not everybody has that readily available. I used to have one of those old torch type leak detectors and it was worthless for everything I ever tried it on. Thank goodness there are better tools out there today. > I used to have one of those old torch type leak detectors and it was > worthless > for everything I ever tried it on. Thank goodness there are better tools > out there > today. I've seen guys who were great with those. Definitely a skill to use, one that was beyond me too.  SignatureBarack Obama, May 9: "I've now been in 57 states? I think one left to go." >> I used to have one of those old torch type leak detectors and it was >> worthless [quoted text clipped - 5 lines] > that > was beyond me too. Well, I do have a TIF5000 detector (http://i20.ebayimg.com/08/i/000/f1/45/d5c1_1.JPG)... but I've had little chance to get used to operating it. I'll definately try it out once I've done testing with pressure & soap solution. > "aarcuda69062" <nonelson@sbcglobal.net> wrote in message news:nonelson- > > What do you propose to pressurize with? [quoted text clipped - 16 lines] > out there > today. Yeah those torch type leak detectors were better at turning refrigerent into nerve gas than finding leaks. The only person in this thread that I know of and would trust my AC sytem to is aarcuda. I'm suprised he's been silent about some of the post here. No offense but I don't think the OP is knowledgeable enough or equipped well enough to tackle the AC system. There are so many basics that aren't even being covered here or followed on. >> "aarcuda69062" <nonelson@sbcglobal.net> wrote in message news:nonelson- >>> What do you propose to pressurize with? [quoted text clipped - 18 lines] > Yeah those torch type leak detectors were better at turning refrigerent > into nerve gas than finding leaks. What, you don't like the smell of phosgene in the morning? (for the few milliseconds you can smell it, anyway) :-p > The only person in this thread that I know of and would trust my AC > sytem to is aarcuda. I'm suprised he's been silent about some of the > post here. No offense but I don't think the OP is knowledgeable enough > or equipped well enough to tackle the AC system. There are so many > basics that aren't even being covered here or followed on. That is quite probably true. But its also reasonably harmless to try to find a large leak with low-pressure air (50 PSI or less). It is interesting to note that most factory service manuals for R-134a systems advise against testing with air, because air/R-134a mixtures in just the right combination and at high enough pressure are apparently combustible. "Heatwave" <m3lt1ng5n0wmen@wah00.com> wrote in message > The only person in this thread that I know of and would trust my AC > sytem to is aarcuda. I have always had a great respect for aarcuda, but AC work is not rocket science. Some of the problems with amateur mechanics is a lack of understanding of AC systems, a lack of equipment to do proper diagnosis, and the tendency to do the job "on the cheap". IMO, if you dont take the time, effort, and expense to do the job properly, you have just thrown away a lot of money. what kind of pressure are you referring too? compressed air?? i hope not air contains moisture and that is a big nono it will cause more issues down the road sooner than you think esp. if you have added any of that r134 with sealer in it it will choke off the whole ac system since you replaced parts go back there and look for bad seals/ torn orings get some r134 with dye added and charge up system then look for leaks > > "aarcuda69062" <nonelson@sbcglobal.net> wrote in message news:nonelson- > > > What do you propose to pressurize with? [quoted text clipped - 24 lines] > or equipped well enough to tackle the AC system. There are so many > basics that aren't even being covered here or followed on. Low side can jump to 2-3 hundred pounds pressure when compressor shuts down. There is no difference in pressure handling ability between the low and high pressure side. > I've decided to take one more stab at fixing my A/C in my '93 Mazda 626... > [quoted text clipped - 7 lines] > > How much pressure can I apply here? Will this do what I need? > I've decided to take one more stab at fixing my A/C in my '93 Mazda 626... > [quoted text clipped - 7 lines] > > How much pressure can I apply here? Will this do what I need? Normal pressures on the high-side are close to 300 PSI. On the low side, operating pressures are around 30 PSI, and pressure with the system off can be around 100PSI. To be safe, I wouldn't use any more than 50 psi to go leak hunting. That should be fairly sufficient. But it may still only spot a really big leak. To find really tiny leaks, especially in evaporator cores, you need a refrigerant "sniffer." >> I've decided to take one more stab at fixing my A/C in my '93 Mazda >> 626... [quoted text clipped - 8 lines] >> >> How much pressure can I apply here? Will this do what I need? > Normal pressures on the high-side are close to 300 PSI. On the low side, > operating pressures are around 30 PSI, and pressure with the system off [quoted text clipped - 4 lines] > leak. To find really tiny leaks, especially in evaporator cores, you need > a refrigerant "sniffer." I do have a sniffer with a new sensor tip... Never had much luck using it, but I didn't have a whole lot of chance to actually test it out. Thx! |
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