Truck AC service question
My truck's AC is low on Freon (shows all the classic signs but still functions). There are two schools of thought on recharging; Have a shop evacuate and recharge the system based on weight fo...
Forum Discussion
You may get a year or two out of a bandaid can, but it can go very wrong and you may damage something like a TXV or compressor. A lot of times when a compressor goes, it will spread metal shavings throughout the entire system, which requires replacing the compressor, expansion valve, condensor, evaporator, accumulator, and flushing all of the piping, which is expensive even if you have all the tools and DIY. The system needs oil in addition to the freon in the right ratio, or it will either underlubricate or deadhead/hydrolock the compressor, both of which significantly shorten the life of the compressor. Part of the drawdown process includes removing/replacing the oil. Also, if there was a leak then chances are the dessicant pack needs replacing too.
I've replaced 4 AC compressors and two entire AC systems myself. If it was my own vehicle I'd never use a "recharge" kit. The tools (other than the vacuum recovery cannister) aren't very expensive.
That being said, if you have a line gauge set and knowledge of how the specific AC system works on your specific vehicle, you can get to the right amount of freon by figuring out where the liquid levels are by careful use of a spray bottle, a line pressure gauge set, and an IR thermometer. You need to make sure no liquid is backing up into the evaporator (it needs to be evenly cold) and that the whole area of the condenser is evenly hot. Too much freon will back up liquid into a place it doesn't belong and decrease the efficiency of the system. If you keep adding beyond that point, it will hydrolock as the compressor cycles and pretty much immediately ruin it.
If you do decide to still add a can, find out how much freon your system is supposed to have, and never add more than 50% of that amount by weight. I use a kitchen scale to watch the mass flow out of the can as I add freon to a system so I know how much I've added.
I've replaced 4 AC compressors and two entire AC systems myself. If it was my own vehicle I'd never use a "recharge" kit. The tools (other than the vacuum recovery cannister) aren't very expensive.
That being said, if you have a line gauge set and knowledge of how the specific AC system works on your specific vehicle, you can get to the right amount of freon by figuring out where the liquid levels are by careful use of a spray bottle, a line pressure gauge set, and an IR thermometer. You need to make sure no liquid is backing up into the evaporator (it needs to be evenly cold) and that the whole area of the condenser is evenly hot. Too much freon will back up liquid into a place it doesn't belong and decrease the efficiency of the system. If you keep adding beyond that point, it will hydrolock as the compressor cycles and pretty much immediately ruin it.
If you do decide to still add a can, find out how much freon your system is supposed to have, and never add more than 50% of that amount by weight. I use a kitchen scale to watch the mass flow out of the can as I add freon to a system so I know how much I've added.
