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This is the second of a 2-part episode in our "CO2 Unfiltered" series where we're joined by Massimo Pellizzari, Senior Commissioning Engineer at Daikin, for an in-depth look at Daikin's two-stage CO2 condensing units (link to Part 1 below). Here, we cover wiring, as well as troubleshooting via the onboard display and buttons, alarm code structure, and conditions like wet operation, high-pressure switch trips, and how the controller can detect overcharge or refrigerant shortage. This 2-part episode is packed with practical insights to help technicians work more faster and more confidently with CO2 condensing units.

(00:36) Power Supply Wiring Basics

(05:44) High Pressure Switch Cutout

(07:07) Reading Alarm Codes

(08:38) Wet Operation and Superheat

(14:21) Expansion Valves for High Pressure

(17:50) Piping Diagram and Valve Locations

(19:49) Subcooling Charts and Charge Errors

(23:40) Recovering or Adding Charge Safely

(26:17) Service Access Basics

(27:56) Backup Modes

(31:44) Setpoints and DIP Switches

(33:52) Piping Logic and P&ID

(37:22) Isolating and Purging CO2

(39:45) Oil Loss and Recharging

(40:55) Valve and Sensor Diagnostics

(47:33) Install Tips and Cleanliness

Helpful Links & Resources:

Massimo in LinkedIn

Daikin

PART 1: Episode 418. Daikin 2-Stage CO2 Condensing Unit Servicing and Troubleshooting with Massimo Pellizzari (Part 1)

Episode 14. What About Condensers in Refrigeration Applications?

Episode 394. Condensing Unit Checkpoints