Diagnose an air conditioner that stopped cooling with ChatGPT and photos

Posted

Jun 5, 2026 by jodacola (Hacker News)

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Last checked

Oct 16, 2026

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Method:

How we verify

Evidence: Described by posterThe person describes what happened in words, without screenshots or video.

Outcome

A landlord whose tenant reported the AC wasn't cooling couldn't get a callback from his HVAC company, so he photographed the outdoor compressor panel and used ChatGPT. He says it walked him through what to check using the diagnostic codes he saw and through replacing a $25 capacitor; the service call alone would have cost almost 4x that.

Agent

ChatGPT

The source didn't share its exact prompt, so we wrote this from what it describes.

Before you start, ask me 1–3 short questions about anything important that's missing below. Keep them quick. Then do the task, checking in with me at the key points.

Goal: Figure out why my air conditioner isn't cooling, and whether it's a simple part I could replace or a job for a technician.

What I can give you (ask for whatever's missing):
- Photos of the outdoor unit's label and the opened service panel
- Any blinking codes or lights on the unit or thermostat
- What happens: fan runs? compressor hums? nothing?
- Age of the system and my comfort with basic electrical work

Safety first: if this involves gas, the electrical panel or mains wiring, structural work, or anything that smells of burning or gas, stop and tell me to call a licensed professional.

Rules:
- Start with the no-tools checks: thermostat mode, breaker, outdoor disconnect, dirty filter, iced coil.
- If you suspect the capacitor or contactor, explain the signs (bulging, burn marks) from my photos and how to read the rating label.
- Spell out the safety steps before touching anything: power off at the disconnect and breaker, and how a capacitor must be safely discharged; if I'm not sure, tell me to call a pro.
- Give the exact part spec to buy (microfarads, voltage) and a typical price.
- Check facts that can change (prices, opening hours, dates, availability, rules) against the official source, and tell me anything you couldn't verify.

Output: Likely cause, the checks I did and their results, the part spec if needed, and a clear go/no-go on DIY.

You'll know it worked when: I either have the right part spec and safe steps, or a clear reason to book a technician.

Before you start, ask me 1–3 short questions about anything important that's missing below. Keep them quick. Then do the task, checking in with me at the key points.

Goal: Figure out why my air conditioner isn't cooling, and whether it's a simple part I could replace or a job for a technician.

What I can give you (ask for whatever's missing):
- Photos of the outdoor unit's label and the opened service panel
- Any blinking codes or lights on the unit or thermostat
- What happens: fan runs? compressor hums? nothing?
- Age of the system and my comfort with basic electrical work

Safety first: if this involves gas, the electrical panel or mains wiring, structural work, or anything that smells of burning or gas, stop and tell me to call a licensed professional.

Rules:
- Start with the no-tools checks: thermostat mode, breaker, outdoor disconnect, dirty filter, iced coil.
- If you suspect the capacitor or contactor, explain the signs (bulging, burn marks) from my photos and how to read the rating label.
- Spell out the safety steps before touching anything: power off at the disconnect and breaker, and how a capacitor must be safely discharged; if I'm not sure, tell me to call a pro.
- Give the exact part spec to buy (microfarads, voltage) and a typical price.
- Check facts that can change (prices, opening hours, dates, availability, rules) against the official source, and tell me anything you couldn't verify.
- Ask me to send a photo of the part label before you name a replacement, so the rating matches.

Output: Likely cause, the checks I did and their results, the part spec if needed, and a clear go/no-go on DIY.

You'll know it worked when: I either have the right part spec and safe steps, or a clear reason to book a technician.

Before you finish: re-read my goal and constraints, check your answer against each one, and list anything you assumed or couldn't confirm.

Source

https://news.ycombinator.com/item?id=48419105