Ref Sensor · Miata sourcing

Cracked A/C cooler pipe

On many early NDs the air conditioning stops blowing cold because a refrigerant pipe cracks. Mazda has a bulletin and a changed part. This page says what the bulletin says. It is not a repair guide.

How to read it. Mazda bulletins are summarised in my own words from the documents I read on 1 October 2026; owner accounts are from Miata.net forum threads, dated below, and are individual experience. There are no prices on this page.

Mazda's bulletin

Mazda North American Operations service bulletin 07-002/21, "Air Conditioner Does Not Blow Cold Air Due to Cracked Cooler Pipe (HI) A (Refrigerant Leak)", last issued 1 February 2021, replaces earlier bulletins from 2018. The U.S. National Highway Traffic Safety Administration holds a copy (PDF), and Miata.net lists it too. I read it. In my words:

  • Cars covered: 2016-2020 MX-5 with VINs lower than JM1ND******418386, built before 10 September 2020.
  • Symptom and cause: the A/C blows warm air because refrigerant has leaked from a crack in the cooler pipe (HI) A, caused by engine vibration. The pipe was changed to a thicker material and its diameter went from 12 mm to 16 mm.
  • Repair: inspect the pipe, and replace it with the modified one if it is cracked; if it is not cracked the bulletin does not apply. The part is NA6W-61-466B, which includes one O-ring (S33P-61-J17); the bulletin says two O-rings are needed. The job includes recharging the refrigerant. Mazda lists the repair as covered by the New Vehicle Limited Warranty for a verified complaint on an eligible car.

The bulletin says its instructions are for skilled technicians and not for do-it-yourselfers.

Bulletins are for dealers, not recalls, and customers should not assume one applies to their car; a Mazda dealer can say whether it does.

Not covered yet

  • Owner accounts: I did not read the Miata.net threads on the cracked pipe.
  • Where to buy the pipe outside a dealer, or an independent shop that will do the job.

© 2026 Fischer Interactive LLC. Written for the Ref Sensor app's Miata users. The seller's page is the authority.