Frozen Lock

This article describes why door locks
freeze, and what you can do about it.

Frozen Lock

Frozen lock
frozen door lock

Why a Door Lock Freezes

House locks, on the average have five pairs
of pins, located within a cylinder, that need
to move freely to engage recesses that
lock the door.
The cylinder that these pins fit into must
also be allowed to rotate freely.

When the key is inserted into the cylinder,
the different shapes cut into the key line
up with the pins that push them into
When the key is inserted and turned the
cylinder rotates and locks or unlocks
the door.

When the outside temperature plunge to
minus 20 to 30 degrees F, any moisture
within the door lock mechanism may
freeze the door lock metal parts solidly
together, especially in windy conditions,
where the chill factor is even lower.

The house door locks that freeze, are the
ones located in rooms cooler that normal
room temperature, such as where a
outside garage door connects to a house.

The garage is usually not heated as well as
inside the house so the lock mechanism
within the door may not stay warm,
which allows the lock mechanism to

The moisture in the warmer air in the
garage tries to escape to the outside
where the air is dryer, the moist air
passes along the edge of the door, and
inside the lock enclosure and lock
assembly parts.

When this moisture contacts the cold
metal of the lock, it freezes.
The moisture content in the air at 30%
will freeze a lock at between -20 to -30
depending on wind chill.

As the moisture content in the home
raises, it takes less cold to freeze the lock.

Older lock assemblies that have been
lubricated at one time, attract dust and
grim over time, the oil and grime dry
out, this causes the lock assembly to
become sluggish, which adds to the

When moisture is added, the water
particles attach to the grime and metal
and freeze the lock mechanism.

Frozen Door Bolt Mechanism
lock bolt freezes

Fixing a Frozen Door Lock

To fix this problem the door lock
mechanism must be removed from the
door and all oil and grime must be
removed from the sliding and turning

Use a Philips screwdriver to remove the
two long bolts (2 inches) which hold the
knob turning assembly together.
Remove the two short screws (3/4 inch)
that hold the bolt sliding mechanism
to the door.

Turning anti-counterclockwise removes.

Slide out the bolt assembly. Wash all the
lock mechanisms thoroughly with Varsol
using a paint brush.

Place the sliding bolt assembly into a
container like a used metal coffee
container, add Varsol, place the lid on and
shake thoroughly.

Dry off all the lock mechanisms with a
cloth and finish drying with an electric
hair dryer or heat gun.

Do not get too close; just close enough to
heat the metal to vaporize the Varsol.

When finished the metal should have a
very dry look. If the knob assembly is
sluggish, also clean it well with Varsol.

lock mechanism lubricants

Lubricating a House Lock Mechanism

A couple of products recommended to
lubricate the lock mechanisms are
WD40, and Lloyds MooVit high
performance penetrating lubricant.
WD40 has more smell than MooVit.

Lubrication is needed to displace moisture
and provide lubrication to the turning,
and sliding mechanisms.

Lightly spray all the moving parts.

Assembling the Lock Assembly

Install the sliding bolt assembly into the
door. The beveled edge points towards
the hole in the door jam.

Secure in place with the two short screws.
Clockwise tightens. Slide the door knob
assembly into place, with the keyed side
facing the outside, and the manual
locking inside.

Secure together with the two long bolts
(2 inches). Start the bolts with finger
pressure to prevent cross threading.

Center the door knob assembly
on the hole in the door and tighten.


For the very difficult frozen lock, carry a
small butane cigarette lighter, heat the
key, the heated key will warm the inside
of the lock, and unfreeze the lock
mechanism momentarily, allowing you
to enter the home.

This action will also work for frozen car
door locks.

Try placing an old woolen sock over the
outside door knob, this may help the warm
air in the house to keep the lock mechanism
from freezing.

You may even consider fashioning a gasket
and O ring arrangement on the inside of
the house door; the door lock mechanism
to prevent moisture from entering into the
lock mechanism.


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