Cold Snap: Frozen Locks, Dead Fobs & Doors That Suddenly Stick

A cold snap brings three kinds of trouble, and each has a plain answer. A frozen lock needs a lock de-icer and patience, never water, force, or a flame on any key. A fob that quits on a cold morning usually has a battery that was already worn, and the small metal blade hidden inside most push-to-start fobs can still open the driver’s door. A house door that suddenly will not latch usually has ice in the strike or a stiff weatherstrip, not a broken lock.

In Evansville, Indiana, that trouble can start with the first freeze in late October. The National Weather Service office in Paducah puts Evansville’s average first freeze in the last days of October and its average first hard freeze, 28 degrees Fahrenheit, around November 8. The earliest first freeze on record came on September 28, 1942.

To thaw a frozen lock, use a lock de-icer made for the job. The ones we trust are alcohol-based, which is what melts the ice. Give the keyhole a short shot, wait, and try the key gently. If it still will not turn, repeat the de-icer rather than turning harder. If a few rounds do not free it, stop and call.

Keep the can in the house or a coat pocket. AAA Club Alliance’s winter guide makes the same point: a de-icer does no good locked inside the frozen car it was meant to open.

A lock freezes when water gets into the keyhole and turns to ice around the small spring-loaded parts the key has to line up. In most house locks those are pins; in most car locks they are flat wafers. On a car, the lock that freezes is usually the one nobody uses: the driver’s keyhole on a car that opens with the remote.

• Hot or warm water. It thaws the surface, then runs deeper into the lock and the door and freezes again, often where de-icer cannot reach it. Some winter advice, including the AAA guide linked above, still suggests warm water; that refreeze is why we do not.
• Force. A key twisted hard against ice can bend or snap, and a snapped key turns a frozen lock into a broken one.
• A flame on any key. The same AAA guide suggests heating a key with a match or lighter, but warns against it for a key with chips or electronics, because an open flame could damage the circuitry. A chip hides inside the key head where you cannot see it, and our guide to identifying your car key explains why most car keys carry one. Even on a plain metal key, we skip the lighter: de-icer works without a flame, and a lock treated with de-icer or hand sanitizer may still hold alcohol, which burns.
• WD-40 & stacked products. Original WD-40 is not the can to reach for on a frozen lock. Locksmith Ledger, a locksmith trade magazine, calls it a temporary penetrating oil for sticky locks, not a lubricant. The same article warns that graphite can cake in the keyhole if moisture or another lubricant gets in. Graphite on top of spray oil on top of whatever went in last winter is how a lock goes from frozen to gummed.

When a car door will not open on a freezing morning, the remote and the key together show where the trouble is. If the remote does nothing, try the key. On most push-to-start cars that means the small blade hidden in the fob, covered in the next section. If the key opens the door, the fob battery is the likely suspect, and the section after that explains why.

If the key will not turn, the ice is most likely in the keyhole, and de-icer is the answer. If the key turns but nothing releases, and the remote failed too, the ice may be deeper in the door. De-icer cannot reach ice in the latch or its linkage, the rods or cables that connect it to the lock, and a fresh fob battery will not free it. Call and tell us what the key and the remote did, and we will tell you on the phone whether it is a job for us.

If the locks release and the handle moves normally, yet the door will not pull open, the rubber seal is usually frozen to the body. That is not a lock problem at all, and yanking the handle in hard cold can snap the handle or the parts behind it.

Most push-to-start fobs carry a small mechanical blade for exactly this morning. Consumer Reports notes that on some cars the matching keyhole hides behind the door handle or under a plastic cap next to it.

That hidden keyhole is usually the least-used lock on the car, so it is the one most likely to be stiff or frozen the day you finally need it. If the cap will not budge, warm it with your hands rather than forcing it. Your owner’s manual shows how the cap comes off. The printed copy usually sits in the glove box, inside the locked car, so use the version most automakers post online.

A dead fob does not always mean a push-to-start car will not start. Consumer Reports also says some cars can still read a fob with a dead battery when it is pressed against the start button or set in a designated spot in the cabin. Ford, for one, has owners set a fob with a dead battery in a backup slot. Depending on year and model, the slot is in the console storage compartment, the cup holder, or elsewhere. Your owner’s manual names the spot for your car.

A fob that quits on the first cold morning usually has a worn battery, not a broken fob. Most push-to-start fobs and remotes run on a flat lithium coin cell. Energizer’s handbook for its lithium coin cells says cold slows the chemical reactions inside the battery and lowers both its voltage and its runtime. The same handbook rates those cells for use down to 30 below zero Celsius, about 22 below Fahrenheit.

An ordinary Evansville winter does not come near that rating. The cold exposes a cell that was already worn, which is why a fading fob so often quits on the first hard freeze. The tells: it works again once it warms in your pocket, or you have had to hold it closer to the car lately.

The fix is a fresh cell with the same number as the one printed on the old cell, put in the same side up. In our experience, swapping the cell in your own fob does not normally erase its programming. Keep new and used coin cells out of reach of children; the same Energizer handbook warns of a serious safety hazard if a coin cell is swallowed.

A house door that closed easily all fall and fights you on a freezing morning rarely has a broken lock. In the cold, we find two usual causes. One is ice in the strike, the metal plate and pocket in the frame that the bolt slides into. The other is a weatherstrip stiff enough to push the door back off the latch. We also see steel doors bow slightly when the outside face is far colder than the inside.

Clear ice from the strike with de-icer rather than water or a screwdriver. Beyond that, leave the strike and the door alone during a cold snap. A door that misfits only on the coldest mornings usually fits again when the weather turns. An outside door that will not latch or lock at all is the exception: call rather than leave it unsecured. A door that still binds on a mild day is not a cold problem. Our guide to rekeying or replacing a lock explains why the door itself is so often the problem.

A few chores on a mild afternoon head off most frozen locks and dead fobs.

• Lubricate exterior door locks and your car’s door keyholes, the hidden one included, with a lubricant sold for locks, applied sparingly.
• If your lock’s maker or your owner’s manual names a lubricant, use that one, and do not layer a second product on top of it. If no maker names one, skip graphite in exterior locks and in any lock that has been sprayed with something else; moisture and other lubricants are what make it cake.
• Put a fresh cell in any fob that has lost range. Not every car warns you before the fob quits.
• Try the fob’s blade in the hidden keyhole once, learn how its cap comes off, and look up your car’s dead-fob start.
• Give outdoor padlocks the lubricant their maker names; they sit in the weather all winter.

Call when a key snaps off in a lock, when the key still will not turn after a few rounds of de-icer, or when a fob with a fresh battery does nothing. On a car, that is work our automotive locksmith service does at the vehicle. Some late-model push-to-start systems are dealer-only, and we will tell you on the phone rather than after we arrive.

A house lock that stays stiff after the ice is gone usually has old lubricant or grit gummed up inside. Cleaning and servicing it is everyday work for our residential locksmith service.

We at A-1 Lock & Safe have worked Evansville winters since 1983, and the first hard freeze brings the same handful of problems every year. Tell us on the phone what froze, what snapped, or what went dark, and the quote you hear fits the job. We confirm the hardware ourselves when we arrive.