NEWS | Aug. 5, 2021

ECU: Refrigerant Change Sparks Alert

Here’s an important message for units: Refrigeration and maintenance services on Environmental Control Unit (ECU) systems that contain a refrigerant known as R22 are no longer authorized to be performed in OCONUS locations in Europe. This restriction includes service procedures like full refrigerant charges and/or “topping off.”

Units can continue to operate ECU systems using R22 until refrigeration services are required. But once any services are due, R22 must not be used and/or serviced.       

Personnel stationed OCONUS who violated international restrictions by continuing to service R22, which has ozone-depleting hydrochlorofluorocarbons, have been penalized and fined by host nations.
OCONUS R22 use may result in host nation fines
OCONUS R22 use may result in host nation fines
As a solution, CECOM’s Integrated Logistics Support Center (ILSC) has tested and approved the use of MO99, also known as R438A, as a safe and suitable “drop-in” replacement refrigerant for R22 in legacy ECU systems.

R438A refrigerant is only authorized for use in the following ECU systems:
BTU/hr NSN 4120- LIN
9,000 (115V) 01-456-6954 A23828
9,000 (208V) 01-330-6542 A23955
18,000 (208V) 01-523-4472 A24463
18,000 vertical 01-329-1515 A24455
36,000 (208V) 01-467-2638 A24763
Unit Instructions
  1. Be aware of any ECU systems that have already been charged (retrofitted) with R438A refrigerant with identification plates stating that the newer refrigerant was applied. Note: This is a critical step to ensure the two refrigerants aren’t mixed, which can cause a chemical/pressure imbalance, making ECU systems NMC.
 Apply identification plates to retrofitted ECUs
Apply identification plates to retrofitted ECU systems
  1. Units performing retrofits should contact the CECOM representatives listed below or LARs to acquire CAUTION identification plates to be attached to retrofitted ECU systems.
  2. R438A retrofits are to be performed on an as-needed basis (attrition), unless units are informed otherwise or unit resources become available.
  3. Units are asked to retrofit ECU systems to R438A prior to deployments in theater.
  4. If R438A is not available through DLA and service is necessary, local purchase is authorized through LAR-approved sources. 
Take note of these R438A refrigerant charging pressures:
BTU/hr R438A lbs
9,000 (115V) 1.90
9,000 (208V) 1.90
18,000 (208V) 2.62
18,000 vertical 3.25
36,000 (208V) 5.70
  1. If you have questions on ECU systems support, contact the following CECOM ILSC POCs:
Sydney Mapp at:

Mike Rankosky at: