Critters in your CarFall/Winter is the most common time that mice or other rodents like to set up homes for the winter--and your vehicle is a favorite target. They can cause extensive damage by gnawing away at under hood wiring or under the dash if they get in.
Part of the blame for their appetite for wiring is from the naturally based compounds that often coat the wiring harnesses. But in many cases, it is simply the desire to stay warm and protected, and the engine compartment or heater ducts is very attractive to them for that purpose.
They can also enter a vehicle's Heater/AC system through the fresh air duct and cause damage to the heater and air conditioner components by jamming them with nesting materials, not to mention the bad odor if they choose to make your heater their final resting place.
If you have problems with them, rather than resorting to noxious poisons or messy traps, here is some tricks and techniques to help keep the little fellas out.
Select the "recirculate" mode rather than "fresh" (when applicable to your vehicle) to block off this entrance into the interior of the vehicle when parking overnight. This closes the outside air door. Often these vents are vacuum operated so switch to the "recirculate" position before shutting off the motor. Note: driving in the recirculate mode in moist weather can cause the windows to fog up.
There are several products that can be used on wiring harnesses to keep them from chewing them and possibly will work in other areas to deter entrance. One we've heard that works is Stop the Rodent which uses highly concentrated formula of peppers and can be ordered from their site and is also available at Amazon.com and other sites.
Another way to fend off mice, rats, squirrels, and chipmunks, tie old socks up with a handful of mothballs (paradichlorobenzene, PDB) inside and place them around the ground or underside of the vehicle. For longer-lasting control, use toilet-bowl PDB cakes. Rodents hate the smell of PDB and will usually stay away.
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