Sometimes the system is buggy, the nozzles on the vacuum cleaners may be broken. If there is a foam gun, it washes well, but in winter they are removed
A hundred-year-old grandfather has more pressure than a washing gun gives out. Washing starts after 10-15 seconds, rinsing is similar. You're wasting precious time, and it still doesn't wash or knock you down. In general, it will be the same as watering from a hose. The vacuum cleaner sucks like my ex, very weakly.