John Hunter Hospital's recent air-conditioning woes have been blamed on faulty chiller units.
Hunter New England Health said engineers were working to repair the chillers located in the air-conditioning towers.
"One is being repaired and will be operational as soon as possible, while the other is being assessed," a spokesman said.
"The remaining chillers are functioning and continue to cool the whole hospital."
There have been reports in recent weeks of significant temperature fluctuations occurring throughout the hospital.
Abbie Kearney was admitted to John Hunter Hospital with a suspected fractured pelvis following a horse riding accident last Wednesday.
A small fan that had been cooling a private room in the ward where the 20-year-old had been recovering was removed some time on Saturday morning.
Left with no air-conditioning, Ms Kearney became nauseous in the stifling heat.
"There wasn't any air in the room, the windows were locked shut," she said.
When her mother Maria Kearney confronted the nursing staff about her daughter's condition and asked for a fan she said she was told to "bring one from home or just go to Bunnings or Woolies, as they are only $20".
Ms Kearney ended up buying two fans, one for her daughter and another for other patients who were in a similar predicament.
Hunter New England Health management contacted Ms Kearney this week to apologise for the incident.
"They told me that staff involved were being re-educated," she said.
The health service also offered to reimburse Ms Kearney for the cost of the fans.
The spokesman told the Newcastle Herald that the comfort and safety of staff, patients and visitors was always the hospital's highest priority.
"We apologise for any discomfort patients may have experienced in the ward affected by temperature fluctuations," he said.
"We encourage anyone experiencing discomfort to speak to staff for assistance."
The hospital was not air-conditioned when it opened in 1991.
However, with ward temperatures routinely reaching the 40s during summer and nurses forced to hand out ice blocks to patients, the state government spent $10 million retro-fitting air-conditioning into wards between 2006 and 2008.
The state government unveiled its master plan for the $780 million redevelopment of the John Hunter Hospital precinct last year.
