Find a failed AC contactor and fix it for $15 with Claude's step-by-step troubleshooting

Posted

Mar 5, 2026 by Brandon Penrod (LinkedIn)

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Last checked

Oct 17, 2026

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Method:

How we verify

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

Outcome

When his thermostat rebooted every time the AC tried to start, a homeowner worked through it with Claude: checking thermostat wiring, then the air handler board and fuse, then isolating the cooling circuit, which pointed to the outdoor unit. There he found a contactor with degraded coil wiring, ordered a $15 replacement and swapped it in 20 minutes. He says the AC runs perfectly, versus a $150 minimum service call he expected to reach $300-400.

Agent

Claude

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

Let's work this out together. I'll tell you what I know, you suggest options and ask what you need, and we'll narrow it down step by step. Nothing gets booked, bought or sent until I say so.

Goal: Let's isolate why my AC won't run, one safe check at a time.

What I'll share as we go:
- What the system does and when
- Thermostat and system type
- My tools (multimeter?) and comfort with 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:
- Work from the thermostat to the indoor unit to the outdoor unit, one check at a time.
- Before any check inside a unit, tell me to switch off power at the breaker and disconnect.
- Explain what each result rules in or out.
- Stop me at refrigerant, capacitor discharge or anything beyond my skill, and say call a technician.
- If a site asks for a login, a CAPTCHA or payment details, stop and hand control back to me.
- Ask for my OK before you pay, book, send, submit or cancel anything.
- Check facts that can change (prices, opening hours, dates, availability, rules) against the official source, and tell me anything you couldn't verify.

Output: A check sequence, the likely failed part and replacement steps.

You'll know it worked when: the AC cools normally after the fix.

Let's work this out together. I'll tell you what I know, you suggest options and ask what you need, and we'll narrow it down step by step. Nothing gets booked, bought or sent until I say so.

Goal: Let's isolate why my AC won't run, one safe check at a time.

What I'll share as we go:
- What the system does and when
- Thermostat and system type
- My tools (multimeter?) and comfort with 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:
- Work from the thermostat to the indoor unit to the outdoor unit, one check at a time.
- Before any check inside a unit, tell me to switch off power at the breaker and disconnect.
- Explain what each result rules in or out.
- Stop me at refrigerant, capacitor discharge or anything beyond my skill, and say call a technician.
- If a site asks for a login, a CAPTCHA or payment details, stop and hand control back to me.
- Ask for my OK before you pay, book, send, submit or cancel anything.
- Check facts that can change (prices, opening hours, dates, availability, rules) against the official source, and tell me anything you couldn't verify.
- Capacitors can hold a dangerous charge even with power off; let a pro handle them if unsure.

Output: A check sequence, the likely failed part and replacement steps.

You'll know it worked when: the AC cools normally after the fix.

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://www.linkedin.com/posts/brandonpenrod_my-ac-died-last-week-thermostat-kept-rebooting-activity-7435313622719012865-XmAV