When Cruz Guzman is dangling from ropes some 20 or 30 stories above the ground, it’s what he can’t see that worries him the most.

“You’re working, and all of a sudden you get those lake-effect storms. You can’t see it from the side of the building you’re working on. Then you get surprised,” said Guzman, 27, who is a second-generation window washer in the city.

In a flash, the ropes are lashing the side of the building like a whip, and the window washer, unable to hold onto anything, is trying desperately to get to the ground.

“It’s the worst feeling out there,” said Guzman, speaking on a cellphone on the side of the Dirksen Federal Building, 15 stories up.

That’s why Guzman and others were out in front of Trump Tower on Monday, demanding higher wages. Guzman and about 260 other window washers in the city are members of SEIU Local 1. Their contract with a number of cleaning companies expires June 30.

The window washers announced that, without a new contract, they’re prepared to go on strike.

The window washers called on Tom Trinen, CEO of Service One, a window washing company based in East Garfield Park, to “create good jobs with fair compensation.”

Trinen said that negotiations have been ongoing since early May and “progress has been made on a number of proposals” and the coalition of companies involved in the negotiations are “committed to resolving all differences in good faith bargaining.”

“Each of the Coalition Companies values its employees and the Coalition’s proposals reflect that,” Trinen said in an emailed statement. “We are confident we will be able to reach an agreement that is mutually beneficial for our employees, our individual Companies and our customers.”

An apprentice washer earns about $12 an hour. Guzman, who has been brandishing a squeegee and a mop for nine years, makes about $20 an hour.

That’s not enough, when you consider having to pay for downtown parking, lunch, health insurance, etc., said Guzman, who is married with two kids.

Guzman said only severe winds and bitterly cold temperatures stop window washers from doing their work.

“It’s a matter of just sucking it up,” he said.

Contributing: Sam Charles