Trains along the 7 line weren't running between Times Square and Hunters Point Avenue because of problems at Grand Central Terminal as of about 11 a.m., according to the MTA's website.
The line was still down about 1 p.m., an MTA spokeswoman said. It was not immediately clear when regular service would resume.
About 12:15 p.m., the N and Q were suspended between 57th Street and Astoria-Ditmars Boulevard because of problems at Queensboro Plaza, the MTA said.
They were running normally, but with delays by 12:40 p.m., a spokeswoman said.
Riders should check the MTA's website for service updates.