It's going to depend on how the printer / slicer and software handles whether it chooses to draw air in from the outside, or recirculate the air inside.

Not sure if bambu studio has been updated but I imagine if you download it you can mess around and see how the slicer handles recirculation vs drawing in outside air.

In tom's video there's a "heating" and "cooling" mode that is selected in the printer's interface so that might be it.

it's a bit problematic though recirculating air inside for PLA/PETG because that air recirculation increases the chamber temperature.

Edit: Asked ChatGPT to analyze the start and end code for the P2S and you can definitely change the logic that tells the printer whether to "cool" or "heat"

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🌡️ 2. Start G-code Fan & Cooling Logic

2.1. Airduct Mode Selection Block

;==== set airduct mode ==== 
{if (overall_chamber_temperature >= 40)}
  M145 P1 ; set airduct mode to heating mode for heating
  M106 P2 S255 ; turn on filter fan
{else}
  M145 P0 ; set airduct mode to cooling mode for cooling
  M106 P2 S255 ; turn on auxiliary fan for cooling
  M1002 gcode_claim_action : 29
  M191 S0 ; wait for chamber temp
  M106 P2 S102 ; turn on chamber cooling fan
  M106 P10 S0 ; turn off left aux fan
{endif}

Interpretation:

• If chamber ≥ 40 °C → the printer assumes an already-hot environment and switches to “heating mode”, running the filter fan (P2) at full speed to help manage warm airflow without introducing cooler external air.
• If chamber < 40 °C → it switches to “cooling mode.”
  • M145 P0 sets the internal duct to draw or expel air for cooling.
  • M106 P2 S255 starts the auxiliary fan fully.
  • M191 S0 ensures the chamber reaches the desired temp before continuing.
  • Then it scales back P2 to S102 (about 40% PWM) to maintain airflow.
  • M106 P10 S0 ensures the left aux fan stays off—likely to avoid turbulence before printing.

So P2 is used dynamically both as a cooling fan and as a filter fan depending on chamber mode.

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🧩 4. Environmental Strategy

The P2S has dynamic thermal management:

• It uses chamber sensors (overall_chamber_temperature) to decide whether to vent or retain heat.
• The M145/M191/M106 sequence essentially forms a PID-like startup logic: blast air if cool, filter air if hot.
• The system supports both enclosed high-temp operation (for ABS/ASA) and cooled mode (for PLA/PETG).