1
Contact us
Call the hotline or send the form below with your equipment model, a description of the fault and your current readings — suction and discharge pressure, room temperature, superheat and subcooling.
Reply within 2 hours
2
Remote diagnosis
An engineer works through the fault tree with you using the values you send, and confirms whether the cause is refrigerant charge, airflow, defrost, control settings or a component failure.
Same working day
3
Repair or part supply
We guide your technician through the repair, or supply the replacement component. Stock items are packed and dispatched quickly so the room is back online with minimum product risk.
Stock parts dispatched in 48 h
4
Verification follow-up
After the repair we compare performance against the commissioning values and confirm the fault has not simply moved elsewhere. A follow-up check confirms the fix held.
Follow-up within 7 days
Why is there frost on my compressor?
Frost usually means the evaporating temperature has dropped too low. The common causes are an undercharge or a slow leak, restricted airflow across the evaporator, a TXV stuck open, or heavy infiltration from door traffic. Measure superheat at the compressor suction: below 3 K points to a flooded evaporator, above 10 K to a starved one. Never simply add refrigerant — find the cause first. See document CX-TC-001.
How do I know if the system is overcharged?
High subcooling (above 8 K), high discharge pressure and a high condensing approach all point to overcharge. Overcharging does not add capacity — it raises energy consumption and risks liquid slugging that damages valves, pistons and bearings. Charge by superheat (fixed orifice) or subcooling (TXV), never by sight glass alone. See document CX-TC-002.
What superheat and subcooling should I expect?
At design load: suction superheat 5–8 K at the evaporator outlet, liquid subcooling 4–8 K at the liquid line. The condensing approach (condensing temperature minus ambient) should sit around 8–15 K. If any of these drifts more than 10% from the commissioning sheet, that is the trigger for investigation. See document CX-TC-009.
My frozen room takes far too long to pull down after defrost.
Check three things in this order: whether defrost terminates on coil temperature or only on time; whether the drain pan and drain line are clear and heat-traced; and whether the fan-delay setting is long enough for residual water to drain. A blocked drain is the most common cause of a coil that "has lost capacity". See documents CX-TC-007 and CX-TC-010.
How often should the condenser be cleaned?
Monthly in dusty or high-traffic environments, quarterly in clean locations. Clean from the inside out, against normal airflow, with low-pressure water and a suitable detergent — never with a high-pressure jet, which flattens the fins permanently. Log the condensing pressure before and after so the improvement is measurable. See document CX-TC-009.
Can I just top up the refrigerant without finding the leak?
No. A system that needs refrigerant every season is leaking, and topping up simply repeats the failure while raising energy cost and environmental impact. Locate and repair the leak, replace the filter drier, then evacuate to below 500 microns and recharge by weight. See document CX-TC-008.
Which refrigerant replaces R404A?
R448A or R449A are the most common non-flammable retrofit options, with capacity close to R404A and no major component change. Expect a higher discharge temperature and mass flow, so verify POE oil compatibility and replace the filter drier. For new low-temperature plant, CO₂ and ammonia systems are increasingly the better long-term choice. See document CX-TC-006.
Do you support systems that CHANGXUE did not supply?
We help with the refrigeration side of any cold-store, whatever the brand of condensing unit. Send the nameplate photo and your readings through the form below and an engineer will advise on the most likely cause and the parts required.
