Nissan Motor has received complaints from owners that its Leaf electric car on occasion fails to start, posing a potential setback for the automaker's goal of promoting zero-emission vehicles.

Japan's No.2 automaker said today it is looking into the exact cause, which it traced back to the Leaf's air-conditioning unit. Nissan is investigating whether the glitch was in a certain component or the programing, spokesman Toshitake Inoshita said.

Nissan Leaf

Nissan plans no recall for now since the issue does not affect safety but will decide how to proceed after identifying the source of the problem, he said.

"When we know the exact cause, we will decide whether to issue a service bulletin, or take other steps," Inoshita said.

He added that the phenomenon was reported in both the United States and Japan, although he did not have an exact figure for the number of complaints.

Nissan and its French partner Renault are aiming to become leaders in the nascent field of electric vehicles, which plug into an electric outlet to power the car's batteries and have no tailpipe emissions.

Nissan launched the five-seater Leaf in Japan and the United States in December. It sold more than 3,300 units in Japan as of February and delivered another 452 in the United States through March.

Production at Nissan's Oppama plant south of Tokyo, where the Leaf is made, resumed today on a normal basis--from supplier-delivered parts--for the first time in a month, after it was halted by a devastating earthquake that rocked northeast Japan on March 11.