A common failure found on many self-contained reach-in coolers and freezers is a low refrigerant charge due to a leak somewhere in the system. Locating the source of the leak and repairing it may be difficult and frustrating at times, but you should always attempt to find the source.
Not attempting to find the source of the leak can be problematic, because if you don’t know the size of the leak, you will likely waste refrigerant, as well as your time. That’s because if you add refrigerant and it leaks out in a relatively short period of time, your customer will not be happy. Even if you had been adding refrigerant to the system over the years and the customer was happy with the “gas and go” repair, you should still sweep the system with your electronic leak detector. Two common locations to always check are the evaporator coil and the discharge line if it runs through the bottom of a condensate pan.
Recently I was working on a two-door reach-in freezer where each year for the past two years I added refrigerant, and the customer was happy with not locating and repairing the leak. The leak was small enough to allow the system to continue to operate for about a year. However, the last time I added refrigerant, I was called out after three days to re-inspect the system and found it was low on refrigerant again. If I had swept the system with my leak detector, I would have found the leak in the discharge line running through the condensate pan.
If you find the system “flat,” there is no sense adding refrigerant without locating and repairing the leak. However, many times you will find the system short of refrigerant — enough to cause it not to operate properly but still with some refrigerant remaining. If the low-side pressure has not been operating in a vacuum, you can elect to add refrigerant, get it operating again, and sweep the system with your electronic leak detector.
If the low-side pressure had been operating in a vacuum, then you have a decision to make. Not knowing the location of the leak, it could have sucked in some air (if the leak is on the low side of the system). You can still add refrigerant to the system, but do you allow it continue to operate if you do not easily locate the leak and the customer is okay with the “gas and go” repair? Not always an easy to decision to make.
On one hand, you have the system operating again (at least until the refrigerant leaks out again), but if the system had sucked in some air, you run the risk of the creating additional problems due to the air trapped in the system. If the customer does not want to you to spend the time and money on the leak search, do you recover the refrigerant, evacuate the system, and recharge? Or let it go and take the risk of not knowing if air is trapped in the system? Definitely a conversation to have with the customer before proceeding. Each choice comes with a risk and an expense, and depending on the age and overall condition of the equipment, not always an easy choice to make.So remember the next time you are faced with a self-contained reach-in with a refrigerant leak, always sweep the system looking for the location of the leak.