Washington (CNN) Air Force One is primed to receive an upgrade that will include new refrigerators expected to cost American taxpayers nearly $24 million.

The US Air Force awarded Boeing a $23.6 million contract in December to replace two of the five "cold chiller units" aboard the aircraft used by President Donald Trump.

"The current rear lower lobe cold chiller units being replaced are the original commercial equipment delivered with the aircraft in 1990. The units were based on the technology at the time and designed for short-term food storage," Air Force spokesperson Ann Stefanek told CNN.

"Although serviced on a regular basis, reliability has decreased with failures increasing, especially in hot/humid environments. The units are unable to effectively support mission requirements for food storage," she said.

President George H. W. Bush talks with reporters aboard Air Force One in 1990. The Boeing VC-25 -- a military version of the 747-200B -- served as Air Force One for Bush as well as Presidents Bill Clinton, George W. Bush and Barack Obama.

President George H. W. Bush talks with reporters aboard Air Force One in 1990. The Boeing VC-25 -- a military version of the 747-200B -- served as Air Force One for Bush as well as Presidents Bill Clinton, George W. Bush and Barack Obama.

President Jimmy Carter waves goodbye as he boards a presidential aircraft on his final day in office in 1981.

President Jimmy Carter waves goodbye as he boards a presidential aircraft on his final day in office in 1981.

With Air Force One in the background, President Richard Nixon delivers a speech at Andrews Air Force Base near Washington after returning from his historic trip to China in February 1972.

With Air Force One in the background, President Richard Nixon delivers a speech at Andrews Air Force Base near Washington after returning from his historic trip to China in February 1972.

From left, astronaut John Glenn, Vice President Lyndon B. Johnson, and President John F. Kennedy arrive at Cape Canaveral Air Force Station in February 1962. Kennedy was the first president to use a customized Boeing VC-137C as Air Force One. The plane was a military version of the Boeing 707. Code-named "SAM 26000," this jet served presidents for more than three decades.

From left, astronaut John Glenn, Vice President Lyndon B. Johnson, and President John F. Kennedy arrive at Cape Canaveral Air Force Station in February 1962. Kennedy was the first president to use a customized Boeing VC-137C as Air Force One. The plane was a military version of the Boeing 707. Code-named "SAM 26000," this jet served presidents for more than three decades.

President Harry Truman's official aircraft, the Independence, served as the presidential plane for almost six years until 1953.

President Harry Truman's official aircraft, the Independence, served as the presidential plane for almost six years until 1953.

The Douglas VC-54C, nicknamed "Sacred Cow," is on display at the National Museum of the United States Air Force, near Dayton, Ohio. Sacred Cow served as President Franklin Roosevelt's official transportation to the Yalta Conference in February 1945.

The Douglas VC-54C, nicknamed "Sacred Cow," is on display at the National Museum of the United States Air Force, near Dayton, Ohio. Sacred Cow served as President Franklin Roosevelt's official transportation to the Yalta Conference in February 1945.

Air Force One flies past an American flag on its way into Daytona Beach, Florida, in 2004. The U.S. Air Force announced Wednesday, January 28, that a customized military version of Boeing's 747-8 will serve as Air Force One for future Presidents. Click through to see the different airplanes that have served as the President's transportation over the years.

Air Force One flies past an American flag on its way into Daytona Beach, Florida, in 2004. The U.S. Air Force announced Wednesday, January 28, that a customized military version of Boeing's 747-8 will serve as Air Force One for future Presidents. Click through to see the different airplanes that have served as the President's transportation over the years.

Due to the fact that Air Force One is a one-of-a-kind aircraft, many of its components require unique testing by the Federal Aviation Administration and the cost of the testing is included in the price of the component, in this case refrigerators. The $24 million contract will cover the costs of engineering support services for the new chillers -- including prototype design, manufacturing and installation, according to the DOD contract.

"The units and associated aircraft structural modifications are being specially designed to provide nearly 70 cubic feet of temperature-controlled (refrigeration/freezer) storage to support on-board personnel for an extended period of time, without having to restock while abroad," Stefanek told CNN.

"The engineering required to design, manufacture, conduct environmental testing and obtain Federal Aviation Administration certification are included in the cost," she said.

Former senior adviser to President Barack Obama Eric Schultz mocked the high price tag in a tweet on Friday, saying, "we would have been impeached."

we would have been impeached https://t.co/KdF82dEseH — Eric Schultz (@EricSchultz) January 26, 2018

The Boeing fridge contract isn't the first time an administration has come under fire for the high cost of military aircraft upgrades -- the Obama administration was pressured to scuttle plans to build a new fleet of presidential helicopters in 2009 after reports emerged that they cost at least $11 billion.

When he was running for president, Trump boasted he would swap out Air Force One with his private jet and has been fiercely critical of the cost of the new Air Force One program in the past, stating "costs are out of control" and "cancel order!" in a December 2016 tweet.

But since taking office, Trump -- like his predecessors -- has traveled aboard the Boeing-made VC-25 aircraft, the latest version of which entered service in 1990.