A six-story Queens apartment building with a large elderly population is losing its only elevator for four months starting Monday — leaving its residents up in arms.

“I am angry and frustrated,” said Farida Ghani, 75, a longtime resident of the 66-unit, pre-war building at 40-66 Ithaca St. in Elmhurst.

Ghani, who uses a walker and lives on the fifth floor, railed, “It shouldn’t take four months. My neurologist has given a letter saying that I could fall and I could hurt my head if I take the stairs.”

Management of the mixed co-op and rental building notified tenants last month that the massive elevator “modernization” project — which includes the installation of new brakes, motor work, wiring and hoist ropes — would begin Monday and take roughly four months to complete.

“Please be advised that management has made arrangements to have staff available to assist residents while the elevator is out of service,” reads a sign posted by the buildings management company, Pinnacle Group, inside the elevator.

Staffers will be available on Sunday, Monday, Wednesday, Friday and Saturday from 10 a.m. to 2 p.m. and 3 p.m. to 7 p.m. “to assist residents,” the sign adds.

But that’s not good enough for some residents.

“I am not happy, nor am I comfortable with this, but I have no choice,” said Amelia Gonzales, 81, who lives on the fourth floor. “I am on dialysis. By the time I get home after dialysis, I feel so weak. I don’t have the energy to walk up and down the stairs.”

She noted that some of her neighbors use wheelchairs.

Carolina Capulong, 71, who lives on the fourth floor, said she is legally blind and that it’s “hard for me to walk.”

“I can’t walk down black stairs. I am blind. I’ve been here for over 27 years. I’ve been taking the elevator for 27 years,” Capulong said.

A lawyer for Pinnacle Group, Ken Fisher, told The Post that the repair work to the elevator “is mandated by city building code and must be completed by Jan. 1.”

Pinnacle “is doing everything it can to get the work done with the least amount of inconvenience for the tenants, but it can’t be done without shutting the elevator for several months,” he said.

Fisher noted the company will have “runners” to help residents during the specified time slots and “at other times by arrangement.”

“They’ve arranged with local grocery stories to make deliveries. They have ordered a piece of equipment that can help people who are infirm go up and down the stairs and they have offered to make additional accommodation for tenants with special needs,” Fisher said.

City Department of Buildings spokesman Andrew Rudansky said an inspection earlier this year “determined that this elevator was in need of repair in order for it to continue to provide safe service for the building’s tenants.”

Fisher said tenants would not see a rent increase as a result of revamp.