Smoke machine to find HVAC leaks

[mendoza0032]

So I have looked and looked, found all kinds of info on finding with smoke machines on evap leaks/intake leaks/exhaust leaks but not really HVAC leaks to find cracks in evaporator/hard lines with smoke machine. Has anyone tried to run smoke thru a/c service port to find a leak? I would think it would be helpful finding really hard leaks. Looking for some feedback if anyone has tried or know of any damage it could cause the system?

 

[Bikes&Bowties]

I feel like either the pressure wouldn't be enough to force a leak as well as temps not being there.

 

[05firecatf7black]

I'm a HVAC tech and yes a lot of AC leaks need high pressure and sometimes high temperatures to appear. Not sure what the smoke machines use to generate smoke but AC systems are great affected by non-condensibles by adding anything other than nitrogen to look for a leak will likely cause further problems down the road. Stick with bubbles, or a good electronic leak detector. As a last resort a good dye and black light can be used but can void compressor warranty

 

[jamesc]

smoke machines are generally 1 psi, sometimes they can be 3 psi anyways you should be able to find a leak quicker with nitrogen at 100+ psi way quicker then the low pressure.


maybe if you filled the system with smoke then introduced the high pressure nitrogen to force the smoke out... I don't know what affect the smoke will have on the a/c system though may harm seals.

 

[GTA Matt]

I know the baby oil smoke machines can leave an oily residue behind, which I am certain would not be good for the ac systems well being.

 

[diesel research]

what you want to do is use the above mentioned ultra violet dyes, refrigerant detector "sniffers", or simple "big blu" micro bubble detector. Sometimes soapy water works, but dedicated bubblers like big blu have even lower surface tension and bubble easier.

Of course, this is used with 100-200psi charge of nitrogen, or as required/capable to withstand, along with a small "diagnostic charge" of R22 of up to 3oz or so. The diagnostic charge may clear away some sludge buildup partially blocking an intermittent leak, is easier to detect with sniffer, is safe for automotive use (as long as vacuumed afterwards) and does not need to be recovered (can be vented in this small diagnostic quantity), per EPA rules.

When you really really cant find it, you can stop and LISTEN. leaks make high pitched whistling noises even in small amounts. Sometimes engine ear type microphones can pick up the "wind noise". Other times dedicated ultrasonic "ears" detect minute sounds above the normal hearing range.

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[cryan]

These days people use electronic sniffers but back in the day on reefer ships we used to use a device like a bunsen burner with a suction hose that you used to sniff around the system. A leak in refrigerant would be sucked up the hose and turn the flame green.