Frozen Lock

Why door locks freeze,
and what you can
do about it.

Frozen Lock

Frozen lock
frozen door lock

Why a Door Lock

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 place.

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 freeze-up.

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 problem.

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

Frozen Door Bolt

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 parts.

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

Turning anti-counterclockwise

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.


Lubricating a House
Lock Mechanism

A couple of products
recommended to lubricate the
lock mechanisms are WD40,
and Lloyds MooVit high
performance penetrating

WD40 has more smell than

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

Lightly spray all the
moving parts.

Assembling the Lock

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

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


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


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