Does refrigerant gas run out? A real cold room leak repair
“My fridge gas is finished — it just needs gas.” It is a common description of a refrigeration fault, but refrigerant is not fuel and is not normally consumed by the refrigeration process. In a sealed system, a shortage of refrigerant means the reason for the loss needs to be investigated.
Refrigerant is not a consumable fuel
A commercial fridge, freezer or cold room circulates refrigerant around a sealed refrigeration circuit. Under normal operation that refrigerant is repeatedly compressed, condensed, expanded and evaporated; it is not burned or deliberately consumed.
If a system that previously contained the correct charge later becomes short of refrigerant, refrigerant has escaped or was lost during previous service work. Simply adding more refrigerant may restore cooling temporarily, but it does not repair a leak. The important diagnostic question is not only “Does it need refrigerant?” but “Why is the refrigerant missing?”
Today's cold-room case
During this service visit, approximately 1 kg of refrigerant was recovered before the circuit was pressure tested. A leak was located during the pressure-test process. The leaking area was repaired by brazing.
After the repair, the circuit was pressure tested again with nitrogen. During the recorded test the manifold showed approximately 29.3 bar. An initial pressure change was observed while the system stabilised; the reading then effectively levelled out, with only about 0.01 bar further change over the following several minutes. The repaired area was checked and no further leak was identified during the test.
Why pressure-test again after brazing?
Finding a leak is only half of the job. After a repair, the refrigeration circuit should be tested again using the appropriate procedure to confirm that the repair is sound and to check for further leakage. A pressure reading immediately after pressurising should also be interpreted with temperature conditions in mind, because gas pressure changes with temperature.
Evacuation and recommissioning
Once the repair had passed the pressure test, the system was evacuated under vacuum. The recovered refrigerant was charged back into the system and an additional 1 kg of R404A was added. The cold room was then restarted, tested and monitored. The system was operating correctly at the end of the visit.
The useful lesson for business owners
If your commercial fridge, freezer or cold room is not cooling and somebody says it is “out of gas”, treat low refrigerant as a symptom that requires diagnosis rather than assuming refrigerant simply needs topping up. A proper investigation can include operating checks, leak detection and, where appropriate, recovery, pressure testing, repair, evacuation and recommissioning.
Repeatedly topping up a leaking system can mean repeated breakdowns, unnecessary refrigerant loss and an unresolved underlying fault. R&S Refrigeration's approach is to identify the cause of refrigerant loss and verify the repair rather than treating refrigerant as a consumable.
What should a customer tell the engineer?
- Whether the equipment is a cold room, freezer, chiller or display cabinet.
- The current temperature and normal set temperature.
- How long the temperature has been rising.
- Whether refrigerant has been added previously and, if known, when.
- Any alarms, unusual noises, icing or recent repair work.
Safety and refrigerant handling
Refrigeration circuits can contain high-pressure refrigerant and pressure-test gas. Recovery, pressure testing, brazing, evacuation and charging require suitable equipment, competence and applicable refrigerant-handling qualifications. This field case explains the diagnostic process; it is not a DIY repair procedure.