A celebrated Santa Barbara farming couple died hours after an emergency call brought paramedics to their friends’ home — but nobody checked the air for the invisible poison allegedly pouring into their bedroom, according to a new lawsuit.

Coffee and exotic-fruit farmer John “Jay” Ruskey, 53, was vomiting, displaying seizure-like symptoms and had lost control of his bowels when his wife, Kristen, 49, called 911 early Feb. 8 as the couple spent the night at their friends’ Cambria home, the suit alleged.

Yet no one tested the air for carbon monoxide, switched off the water heater allegedly leaking the diᩚadℓy gas or ventilated the rooms, the lawsuit claims.

The couple returned to bed. Hours later, both were found dead at the friends’ home, per the San Luis Obispo County Sheriff’s Office.

Their three children — Kasurina, 19 at the time, and 16-year-old twins Aiden and Sean — are suing homeowners Ben and Robin Korman and water heater manufacturer Navien Inc. over the deaths.

The complaint alleges a failed exhaust system and a disconnected carbon monoxide detector left the Ruskeys exposed to a lєthaℓ threat during an overnight stay at the Kormans’ Cambria property.

The suit claims that without an alarm or working detector, “neither the responding personnel nor the Korman Defendants nor anyone else at the Subject Property identified carbon monoxide as the cause of Jay’s symptoms.”

The couple had attended a birthday bash with roughly 50 to 60 guests on Feb. 7 before settling into a guest bedroom around 2 a.m., according to the suit.

As the household’s demand for hot water kept the tankless heater firing, carbon monoxide escaped through its allegedly failed venting system into the laundry room and adjoining bedroom, the complaint alleges.

The only smoke and carbon monoxide detector in or immediately outside the bedroom had allegedly been disconnected from its wiring before the Ruskeys arrived, the suit claims.

“No alarm ever sounded,” the lawsuit states.

Kristen called 911 around 4:34 a.m. as Jay’s condition deteriorated.

According to the Santa Barbara Independent, she told responding medics that her husband had eaten chocolate containing psychedelic mushrooms and was having a “bad trip.” Partygoers reported hearing him scream and vomit.

Paramedics recommended hospital treatment, but Jay declined, the outlet reported.

The lawsuit says his symptoms were potential signs of acute carbon monoxide poisoning, yet the gas went unrecognized.

Without a functioning detector, neither responders, the homeowners nor anyone else at the property identified carbon monoxide as the source of his distress, the complaint states.

It also alleges that “no one tested the air in the Guest Bedroom or the Laundry Room, shut off the Subject Water Heater, or ventilated the space.”

Guests checking on the couple around 9:30 to 10 a.m. found Kristen on the laundry room floor near the connecting doorway and Jay in bed, pulseless and not breathing, according to the suit.

They began CPR, and another 911 call followed around 10:20 a.m. Despite resuscitation efforts, both were pronounced dead at the property.

Their deaths were ruled accidental, the Independent reported. The complaint says autopsies revealed findings characteristic of carbon monoxide poisoning.

The Ruskeys were agricultural trailblazers behind Good Land Organics and Frinj Coffee, helping establish California-grown coffee while raising unusual fruit crops in western Goleta.

Their children’s suit seeks product liability damages from Navien and premises liability damages from the Kormans.

For the couple’s children, the loss erased a family life filled with camping, mountain biking, paddleboarding and cookouts at their farm.

“They lost two committed parents and a lifetime of love, support, guidance, and comfort,” the complaint states.

The California Post contacted Navien Inc. and the Kormans for comment.