Coolant bleeding — removing air after repair

Description

After coolant system repair the coolant doesn't circulate — the fluid sits still when the procedure is started in Service Mode. The computer temperature climbs to 80-90°C. The cause is an air pocket.

Solution: two scenarios

The main rule (per the original Tesla manual): after removing and installing the HV battery the system may only be refilled with a vacuum created. Without vacuum, bleeding is acceptable only for a top-up or a minor repair — for example, when the radiator was removed for cleaning.

Scenario 1: minor repair / top-up (no vacuum)

1. The nose of the car must be raised (jack or ramp) — air goes up and out.
2. Run the air bleed procedure (Coolant Air Purge) via Service Mode.
3. Watch the temperature — stop at 80°C, let it cool, repeat.
4. Several bleeding cycles may be required.
5. Don't forget to top up coolant after the procedure.

Scenario 2: after HV battery removal — vacuum refill only

The procedure per the Tesla manual:

1. In Service Mode start the Coolant Fill/Drain mode (in Toolbox — procedure PROC_VCFRONT_X_THERMAL-FILL-DRAIN). The drive rails must be off — otherwise the procedure will stop.
2. Remove the coolant reservoir cap and fill the system: on cars with a heat pump — to the MAX line, on cars without a heat pump (superbottle) — roughly 6 mm above MAX.
3. Create a vacuum with the vacuum rig on the bottle — it is the vacuum that pulls the coolant into the empty loops and leaves no air pockets.
4. Run Coolant Air Purge: in Service Mode — Thermal → Coolant System → Coolant Purge Start (in Service Mode Plus — via Drive Unit / Drive Inverter Replacement → Coolant Air Purge; in Toolbox — TEST_VCFRONT_X_THERMAL-COOLANT-AIR-PURGE).
5. The procedure runs for about 10 minutes, the pumps vary their speed between 3,500–6,500 RPM (visible on the PT Thermal tab). While it is running — keep the level between NOM and MAX, topping up as the fluid moves into the loops.
6. If the speed hovers around 7,000 RPM — air remains, so repeat the procedure.
7. After it finishes, top up to the norm: with a heat pump — to MAX, without one — ~6 mm above MAX. Close the reservoir cap.

Community experience TESLA Belarus

From the TESLA owner's group BELARUS chat — analysis of 400 000 messages.

Who reported the issue: Ruslan

Who found the fix: Pasha n1claus, Denis

Discussion in Telegram: #129269

When bleeding is most often needed

Coolant bleeding with air removal is usually required after any work where the system was opened:

• Replacing the heat pump or its components (octovalve, supermanifold) — on Model Y the heat pump with the octovalve has been fitted since launch (2020), on Model 3 — since the 2021 model-year refresh (2021 heat pump issues).
• Replacing the A/C compressor or refrigerant lines (Model 3/Y AC compressor failure).
• Cleaning / replacing the radiator and A/C condenser — coolant usually spills during disassembly (radiator and condenser cleaning).
• Replacing the drive unit, especially the LDU (Large Drive Unit) — it shares the cooling loop with the battery (LDU problems S/X).
• Any HV-battery work where the pack coolant was drained — here vacuum refill ONLY (scenario 2).

In all these cases a standard refill via Service Mode will hit the airlock unless the procedure above is performed.

Links

• Cooling System Refill and Bleed — Tesla Service Manual: https://service.tesla.com/docs/ModelS/ServiceManual/Palladium/en-us/GUID-A474F6DC-B48D-4184-8B5F-A4A4FB8ED1FA.html
• Cooling System Bleed — Model 3 Service Manual: https://service.tesla.com/docs/Model3/ServiceManual/2024/en-us/GUID-16455A85-902B-4E9A-84FE-F6EF7BC0D0FB.html