A windscreen washer may seem unimportant on a dry driveway. Its weakness becomes obvious when road spray leaves a film across the glass. Check the system while the car is parked safely, before a journey makes visibility a problem.
Begin with the owner’s manual
Identify the correct reservoir and approved fluid specification. Do not add household detergent or guess from the colour of an unfamiliar cap. Products and dilution requirements vary with the vehicle and expected temperature; use the instructions for both the car and the fluid.
If the reservoir is low, refill as directed and look for an obvious leak beneath the parked vehicle. Avoid running the pump repeatedly when the reservoir is empty. A weak spray, no spray and a spray aimed away from the glass are different observations worth reporting.
Observe without dismantling
Briefly operate the washers from the normal driving position while stationary. Notice whether both sides work, whether the fluid reaches the intended area and whether the wipers clear it. Inspect accessible surfaces for dirt or ice only when safe. Do not poke a needle into a nozzle unless the manufacturer explicitly permits that method; some designs are easily damaged or misaligned.
In freezing conditions, follow the manual’s advice and allow the system to thaw safely. Pouring hot water over cold glass or forcing a frozen mechanism is not a sensible diagnostic shortcut.
If the problem persists, tell a workshop what happened: “The pump can be heard, the reservoir is filled correctly, but only the left nozzle sprays.” That narrows the conversation more than simply saying the washers are bad. Electrical, pump, hose and nozzle faults need different checks.
After a repair, test again while parked and confirm that the glass clears properly. If visibility becomes inadequate on the road, stop somewhere safe and resolve it. A clean windscreen at departure is useful; a working way to clear it during the trip is essential.