TestEquity 123HS, Operation And Service Manual

Page: 43 / 53

Chapter 7 – Maintenance
TestEquity 123HS Temperature/Humidity Chamber Page 7-13
Refrigeration System Charging Instructions
! WARNING: Repair of the refrigeration system must be performed only by a properly
trained mechanic who is experienced in repairing cascade refrigeration
systems. Do NOT substitute any component. Do NOT substitute refrigerants.
Improper repairs will void the warranty.
These instructions are intended as guidelines for repairing TestEquity chambers. Details such as
how to attach a gauge manifold are not covered. These are NOT do-it-yourself instructions!
Refrigerant Charge
TestEquity does NOT recommend charging the system by relying on a clear sight glass only.
Although a clear sight glass generally means the system is fully charged, it can be misleading.
For example, if the system is charged on a cool day or with an empty chamber, it could be
undercharged for hot days or with a heavy load. The proper charging procedure is as follows:
1. Repair any leaks before recharging.
2. Attach a vacuum pump and manifold gauge to the suction and discharge ports.
3. Evacuate the system to at least 100 microns. DO NOT GUESS! You must use a micron
gauge.
4. Use a charging scale to weigh in 14 ounces of R-404A.
5. Verify the cooling performance as outlined in “How to verify the chamber performance”.
NOTE: If the F4/F4T Controller is cycling (Cool Light cycles on/off), the sightglass may appear
1/2 to 2/3 full. This is normal.