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Root Cause & Key Technical Context: If your Autopilot / FSD computer is overheating, you are dealing with a broader thermal management issue. Common culprits include a clogged radiator, low coolant levels, air pockets in the cooling lines, degraded thermal paste on the AP computer, or most commonly overlooked a low refrigerant charge. Vehicle info: 2019 Model 3 SR+ 153k miles in Phoenix its entire life. Symptoms Experienced Intermittent Autopilot/FSD Lockouts: System disengagements during afternoon commutes in extreme ambient heat 115°f+ starting back on FSD v12.6.4. On June 8th. Would drop out for a couple minutes then let me re-engage before throwing red hands again. Service Mode Insights: Service Mode logged a silent thermal alert once the processor hit 90°c leading to full "red hands" disengagements at 95°c, no other alerts present. Post-Supercharging AC Dropout: Cabin A/C stopped blowing cold air for 1–3 minutes immediately after unplugging from a Supercharger in severe ambient heat, accompanied by an FSD temperature lockout. Diagnostic & Troubleshooting Process Physical Radiator Inspection & Cleaning: Had Tesla clean the front radiator assembly to clear external debris. (Issue persisted) Coolant Vacuum Degas / Purge: Had an independent EV specialty shop perform a full coolant vacuum bleed to eliminate potential air pockets. (Issue persisted) Thermal Performance Self-Test (Service Mode): Ran the thermal performance test in Service Mode, which repeatedly failed with the error:“The refrigerant flow target through the chiller EXV was greater than expected. Check for low refrigerant charge.” Refrigerant Evacuation & Recovery Test: Returned to the independent EV shop to measure the exact refrigerant volume. The system recovered only 486g out of the 660g factory capacity (174g low). Why Low Refrigerant Causes Autopilot Overheating When refrigerant levels fall below threshold in extreme heat, the HVAC system cannot manage all thermal loads simultaneously. The vehicle prioritizes cabin cooling and basic battery safety over compute cooling, effectively starving the electronic chiller circuit. Higher compute loads (such as FSD v12.4+) drive up processor power consumption and operating temperatures, rapidly eating away at your thermal headroom if the fluid cooling loop isn't operating at full capacity. Takeaway: Before replacing an expensive Autopilot computer, which often only offers temporary relief due to fresh thermal paste, check your refrigerant level. In high-heat climates (like Arizona), minor, natural permeation over several years can easily drop your refrigerant charge enough to starve the chiller and cause compute thermal lockouts. Since EVAC and recharge I have had no issues with my autopilot overheating and the car is running a lot calmer. V14 Lite is not the issue, your thermal management system has a deficit somewhere even if it’s not the refrigerant like in my case. Tesla likes to throw expensive unnecessary computer replacements at you, if you run a thermal test and back out in service mode to the coolant loop temps you can watch them actively drop as well. If your autopilot board temp decreases during a thermal test then it’s responding to and changing temperature like it’s supposed to and is not necessary to have it replaced. Sorry it’s long just thought I’d post on this issue and hopefully it helps someone! 😊

phxaidriven's tweet photo. Root Cause & Key Technical Context:
If your Autopilot / FSD computer is overheating, you are dealing with a broader thermal management issue. Common culprits include a clogged radiator, low coolant levels, air pockets in the cooling lines, degraded thermal paste on the AP computer, or most commonly overlooked a low refrigerant charge.

Vehicle info: 2019 Model 3 SR+ 153k miles in Phoenix its entire life.

Symptoms Experienced

Intermittent Autopilot/FSD Lockouts:
System disengagements during afternoon commutes in extreme ambient heat 115°f+ starting back on FSD v12.6.4. On June 8th. Would drop out for a couple minutes then let me re-engage before throwing red hands again.

Service Mode Insights:
Service Mode logged a silent thermal alert once the processor hit 90°c leading to full "red hands" disengagements at 95°c, no other alerts present.

Post-Supercharging AC Dropout:
Cabin A/C stopped blowing cold air for 1–3 minutes immediately after unplugging from a Supercharger in severe ambient heat, accompanied by an FSD temperature lockout.

Diagnostic & Troubleshooting Process

Physical Radiator Inspection & Cleaning: Had Tesla clean the front radiator assembly to clear external debris. (Issue persisted)

Coolant Vacuum Degas / Purge:
Had an independent EV specialty shop perform a full coolant vacuum bleed to eliminate potential air pockets. (Issue persisted)

Thermal Performance Self-Test (Service Mode):
Ran the thermal performance test in Service Mode, which repeatedly failed with the error:“The refrigerant flow target through the chiller EXV was greater than expected. Check for low refrigerant charge.”

Refrigerant Evacuation & Recovery Test:
Returned to the independent EV shop to measure the exact refrigerant volume. The system recovered only 486g out of the 660g factory capacity (174g low).

Why Low Refrigerant Causes Autopilot Overheating When refrigerant levels fall below threshold in extreme heat, the HVAC system cannot manage all thermal loads simultaneously. The vehicle prioritizes cabin cooling and basic battery safety over compute cooling, effectively starving the electronic chiller circuit.

Higher compute loads (such as FSD v12.4+) drive up processor power consumption and operating temperatures, rapidly eating away at your thermal headroom if the fluid cooling loop isn't operating at full capacity.

Takeaway: Before replacing an expensive Autopilot computer, which often only offers temporary relief due to fresh thermal paste, check your refrigerant level. In high-heat climates (like Arizona), minor, natural permeation over several years can easily drop your refrigerant charge enough to starve the chiller and cause compute thermal lockouts.

Since EVAC and recharge I have had no issues with my autopilot overheating and the car is running a lot calmer.

V14 Lite is not the issue, your thermal management system has a deficit somewhere even if it’s not the refrigerant like in my case. Tesla likes to throw expensive unnecessary computer replacements at you, if you run a thermal test and back out in service mode to the coolant loop temps you can watch them actively drop as well. If your autopilot board temp decreases during a thermal test then it’s responding to and changing temperature like it’s supposed to and is not necessary to have it replaced.

Sorry it’s long just thought I’d post on this issue and hopefully it helps someone! 😊

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