OpenWeathermap country codes code proplem “city not found”

im writing a code for a weather journal app the thing is when i pass to fetch method the url of the site of openweathermap.com with the zip code and country code way it only accepts the country code as US it never accepts anyother country i tried so many but it never accepts any of those it only returns the data object of forecast to US anyother country it just show the message city not found here is my code:

const generate = document.getElementById('generate').addEventListener('click', function(){
    const zip = document.getElementById('zip').value;
    const countryCode = document.getElementById('countryCode').value;
    endPointData(zip,countryCode,apiKey);
})

const endPointData = async (zip,countryCode,apiKey) => {
    const res = await fetch(`https://api.openweathermap.org/data/2.5/weather?zip=${zip},${countryCode}&appid=${apiKey}`);

    try{
        const data = await res.json();
        console.log(data);
    }
    catch(error){
        // appropriately handles the errors.
        console.log("error",error);
    }
}

const postData = async (url='', data = {}) => {
    const response = await fetch(url,{
        method: 'POST',
        credentials: 'same-origin',
        headers: {
            'Content-Type': 'application/json'
        },
        body: JSON.stringify(data),
    });
    try{
        const newData = await response.json();
        return newData;
    }catch(error){
        console.log("error",error);
    }
}