Dryer Air Flow
The basic dryer air flow direction for all dryers is the same. Air enters the back of the dryer near the motor and passes through the motor to keep it cool. This is why you should never operate a dryer without a vent! If a dryer does not have a vent the humid, dusty air exits the dryer and immediately reenters via the air inlet. Lint builds up on the motor creating a fire hazard and premature motor failure. Under normal conditions cool air passes through the motor and is forced by the blower past the heater into the drum. The now hot air passes through the clothes and enters the filter. It then leaves the dryer via the air duct that exits out the back of the dryer where you connect the vent.
Basic Dryer Electrical Operation
Electric dryers in the US operate on two 110 volt A/C circuits. The two 110 volt circuits combine to deliver 220 volts A/C to the dryer heater. See the basic dryer heat circuit.
The dryer motor operates on 110volts A/C. Dryer receptacles have an L-shaped neutral post. You can check the voltage to your dryer by slightly sliding the cord out of the receptacle and using the leads from a multi meter to check for voltage on the blades of the cord that slide into the receptacle.
Between the left and the right blades you should read 220 volts. Between the left or right blade to the center blade (the L-shaped blade) you should read 110 volts AC.
The 4-post receptacle has an L-shaped neutral and a seperate ground. It requires a 4 wire cord and the ground wire is isolated from the neutral on the dryer