GM bulletin PIT6556
What it saysThis Preliminary Information, describes a condition where the HVAC will make noise when changing modes while HVAC is warm. NHTSA’s full summary ↓
GM filed this with NHTSA as a service bulletin dated Oct 15, 2026, received Oct 19, 2026. It names 6 model years across Chevrolet and GMC (2025–2027). A service bulletin is not a safety recall: it is the manufacturer telling its dealers how to diagnose or repair a condition, and whether the work is paid for depends on the warranty in force. Quoting the number at a service desk can save a diagnosis.
One page for every brand it was filed under. Each brand’s bulletins: Chevrolet · GMC.
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What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationThis Preliminary Information, describes a condition where the HVAC will make noise when changing modes while HVAC is warm. Engineering is aware and no fix available at the time.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| PIT6556 | Service bulletin | Oct 15, 2026 | 11038588 | PDF, 105 KB |
The summary is NHTSA’s abstract of the document, as filed under 49 CFR 579.5. One communication is usually filed as several documents — the bulletin, a dealer notice, an owner letter — and the number on any of them finds this page. A PDF link is shown only once NHTSA’s own server has been seen to serve that document; the rest are checked over the following nights. Quote the number at a service desk; it is what the dealer’s system is keyed on.
Model years it names
Source: as the manufacturer filed themChevrolet 3 model years
GMC 3 model years
A vehicle page’s bulletin list shows the newest few communications filed against that model year; the count there is every one.
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What owners reported
Source: NHTSA complaint databaseOwners of the 6 model years this bulletin names have filed 535 complaints with NHTSA since 2015.
A complaint is one owner’s account, not a defect finding, and a bulletin is not a recall. Nothing here says this bulletin was issued because of these complaints, or that the repair it describes fixed them. Complaint files on this site begin in 2015.
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Chevrolet and GMC, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is GM PIT6556 a recall?
No. A service bulletin is a manufacturer communication filed with NHTSA under 49 CFR 579.5; a safety recall carries an NHTSA campaign number (two digits, a letter, six digits) and a federal duty to repair for free. Check the vehicle’s recalls by VIN at nhtsa.gov/recalls, or on its page here.
Is the PIT6556 repair free?
Not automatically. A service bulletin describes how to diagnose or repair a condition; who pays depends on the warranty in force, any extension, and the dealer. Quoting the number can save a diagnosis either way. Every GM warranty extension on file lists the ones GM has filed.
Which vehicles does PIT6556 cover?
The manufacturer filed it against 6 model years across 2 brands (Chevrolet and GMC): 2027 Chevrolet Equinox, 2026 Chevrolet Equinox, 2025 Chevrolet Equinox, 2027 GMC Terrain, 2026 GMC Terrain, 2025 GMC Terrain. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.