Winter Visibility: Wipers, Fluid and a Defroster That Works

Traction gets all the attention in winter driving and visibility causes at least as many problems. Salt spray from a truck on I-35 can blind a driver completely for several seconds, and what happens next depends entirely on equipment that costs very little. Call Des Moines Auto Repair at (515) 305-3210 for a pre-winter check.

Washer fluid is not interchangeable

Summer fluid freezes. It freezes in the reservoir, in the lines, and worst of all on the windshield the moment it is sprayed, which turns poor visibility into none at all at highway speed.

Winter fluid rated to twenty below or lower is the item to have in the car before the first cold snap. Topping a half-full reservoir of summer fluid with winter fluid dilutes the rating, so it is worth running it low first.

Carry a spare gallon. A tank empties surprisingly fast on a salted interstate and there is no substitute available at the roadside.

Blades wear out faster than people replace them

Rubber hardens with age and with UV exposure, and Iowa gives blades a brutal year — baked in July, then scraping frozen glass and salt crust in January. Six to twelve months is realistic.

The signs are streaking, chattering, or a section of glass the blade no longer contacts. Any of those means replacement rather than cleaning.

Winter-specific blades with a covered frame resist ice packing into the linkage, which is what stops a conventional blade following the curve of the glass.

Do not use the wipers to clear ice

Running a wiper across a frozen windshield tears the rubber edge and can burn out the wiper motor if the blade is frozen down. Clear the glass first, then use them.

Lifting blades off the glass overnight prevents them freezing to it, though it does leave the springs under tension. Either that or a blade cover works.

The defroster, and how to use it properly

The fastest way to clear a fogged windshield is heat, maximum fan, air conditioning on, and recirculation off. The compressor dehumidifies the air, which is what actually clears fog rather than merely warming it.

Recirculation traps the moisture you and your passengers are producing inside the cabin, which is why a car fogs up worse with it on. Fresh air is drier even when it is cold.

A rear defroster works by resistance grid rather than airflow and takes a few minutes. Scraping the inside of a rear window with an ice scraper destroys those elements.

Where fog comes from

Persistent interior fogging that never quite clears usually means moisture in the cabin. A leaking cabin air filter housing, a plugged evaporator drain, wet floor mats, or snow carried in on boots all contribute.

A heater core beginning to leak produces an oily film on the inside of the glass and a sweet smell, and that is worth diagnosing rather than wiping.

Lights matter as much as glass

Salt film on headlights and taillights reduces output substantially, and clouded plastic lenses do the same. Wiping the lights when you fill up takes a moment and makes a real difference.

Check that all of them work before winter, since being seen from behind in blowing snow is worth as much as seeing forward.

Clearing the whole car, not a porthole

Iowa law and basic sense both point the same way here. Snow left on a roof slides onto the windshield during the first hard stop, and it blows off onto the vehicle behind you at highway speed.

A snow brush with a long handle and a proper foam blade clears a roof without scratching paint. Clear the hood as well, since snow there blows up onto the glass the moment you get moving.

Lights, mirrors, and the rear window come next, and the sensors on newer vehicles need clearing too. A blocked forward radar behind the grille disables adaptive cruise and automatic braking, usually with a warning on the dash.

Frozen door locks and seals

Doors freeze shut when meltwater refreezes in the seal, and forcing one tears the rubber. A silicone treatment on the seals in fall prevents most of it.

Never pour hot water on a frozen windshield or lock. The thermal shock cracks glass, and the water refreezes in the mechanism within minutes.

Keep a lock de-icer somewhere other than inside the car, which is the classic mistake.

We serve Des Moines and the surrounding metro. Call (515) 305-3210.