Air con stopped working. Greasy stain on pipe. Leak?
Discussion
The air con on my wife’s Suzuki has suddenly stopped working. I’ve noticed a greasy, slightly tacky stain on one of the pipes. I’m sure it was clean before. Is that what leaked gas would feel/look like?
See below, it’s just underneath the little pipe which spurs off so I suspect it’s gone on the join.
See below, it’s just underneath the little pipe which spurs off so I suspect it’s gone on the join.
I'm actually an automotive AC specialist by trade, firstly if it was just refrigerant leaking there would be no trace, the pipe may freeze over initially but would soon warm up show no sign.
The pag oil that is used as a lubricant may well leave a stain if enough leaked out but generally the amount in circulation is pretty low.
Take it to someone who knows what they are doing rather than a fast fit who just want to regas it in the hope it magically fixes itself.
If when they connect onto the vehicle there is zero pressure showing on the gauges then there is a leak and that pipe is prime suspect.
If there is some pressure it may still be a leak, albeit a slow one. Some garages will rely on the AC machine doing a vacuum leak test but this isn't definitive and can give a false positive.
The best way to leak test is using nitrogen/hydrogen gas, they can use a specific leak detector to trace the source of the leak. Once the leak source has been confirmed it's just a case of replace the pipe then run a full cycle to recharge the vehicle.
The pag oil that is used as a lubricant may well leave a stain if enough leaked out but generally the amount in circulation is pretty low.
Take it to someone who knows what they are doing rather than a fast fit who just want to regas it in the hope it magically fixes itself.
If when they connect onto the vehicle there is zero pressure showing on the gauges then there is a leak and that pipe is prime suspect.
If there is some pressure it may still be a leak, albeit a slow one. Some garages will rely on the AC machine doing a vacuum leak test but this isn't definitive and can give a false positive.
The best way to leak test is using nitrogen/hydrogen gas, they can use a specific leak detector to trace the source of the leak. Once the leak source has been confirmed it's just a case of replace the pipe then run a full cycle to recharge the vehicle.
blue_haddock said:
I'm actually an automotive AC specialist by trade, firstly if it was just refrigerant leaking there would be no trace, the pipe may freeze over initially but would soon warm up show no sign.
The pag oil that is used as a lubricant may well leave a stain if enough leaked out but generally the amount in circulation is pretty low.
Take it to someone who knows what they are doing rather than a fast fit who just want to regas it in the hope it magically fixes itself.
If when they connect onto the vehicle there is zero pressure showing on the gauges then there is a leak and that pipe is prime suspect.
If there is some pressure it may still be a leak, albeit a slow one. Some garages will rely on the AC machine doing a vacuum leak test but this isn't definitive and can give a false positive.
The best way to leak test is using nitrogen/hydrogen gas, they can use a specific leak detector to trace the source of the leak. Once the leak source has been confirmed it's just a case of replace the pipe then run a full cycle to recharge the vehicle.
very much this, a vacuum test doesnt always show a leak, sometimes a seal or similar can work in vacuum but not under pressure, a pressure test with a inert gas is the best wayThe pag oil that is used as a lubricant may well leave a stain if enough leaked out but generally the amount in circulation is pretty low.
Take it to someone who knows what they are doing rather than a fast fit who just want to regas it in the hope it magically fixes itself.
If when they connect onto the vehicle there is zero pressure showing on the gauges then there is a leak and that pipe is prime suspect.
If there is some pressure it may still be a leak, albeit a slow one. Some garages will rely on the AC machine doing a vacuum leak test but this isn't definitive and can give a false positive.
The best way to leak test is using nitrogen/hydrogen gas, they can use a specific leak detector to trace the source of the leak. Once the leak source has been confirmed it's just a case of replace the pipe then run a full cycle to recharge the vehicle.
richhead said:
very much this, a vacuum test doesnt always show a leak, sometimes a seal or similar can work in vacuum but not under pressure, a pressure test with a inert gas is the best way
If I had a quid for everyone who said the previous garage did a leak check and it passed but now it's not working again I'd be writing this from a yacht in Monaco and not a caravan in the vendee!Gassing Station | Home Mechanics | Top of Page | What's New | My Stuff