The first thing you will need to learn to be able to easily repair your not heating Whirlpool 27 inch gas dryer is how to take it apart and how to put it back together again properly. Once you learn how to do that, the repairs will be very easy to do.
The igniter is used to ignite the gas once the gas valve starts to release the gas. Once the gas is ignited, the igniter is turned off by the flame sensor and it stays off until is needed again to ignite the gas.
The Flame Sensor
The flame sensor is a switch use to turn on and off the igniter as needed. This switch is controlled by heat. When the timer calls for heat the igniter starts to get hot until is red hot. The heat from the igniter close the flame sensor and the gas valve opens to release the gas. When the gas reach the still red hot igniter it get ignited to start the dryer starts drying the clothes.
Gas Valve Coils
These coils are on top of the gas valve and are used to open and close the gas valve as needed. If one of the coils fails, the gas valve will not open to released the gas.
Thermal Cutoff Thermostat
This thermostat is used as a safety device to open the circuit if the heat element housing gets hotter that 305 degrees Fahrenheit. This will only happens if there is a restriction on the airflow from the inside to the outside.
Cycling Or Operating Thermostat
A bad cycling thermostat could be the reason why your Whirlpool 29 inch gas dryer is not drying the clothes properly or not drying at all.
This thermostat is used to control the temperature inside of the tumbler. It is rated at 155 degrees Fahrenheit plus or minus 20 degrees.
This thermostat could be working ok eclectically, but not opening and closing at the proper temperature. If your dryer is not heating at all, you will need a multimeter to check for continuity in the thermostat.
Hi Limit Thermostat
This thermostat is used to open the heater circuit if the thermal cutoff fails to blow and open the circuit.
Bad timer contacts could be the reason why is the dryer is not producing heat. With time and usage the contacts will burn out and won't be able to close the circuit for the dryer to heat up.
Motor Centrifugal Switch
The motor could run ok to turn the dryer tumbler around, but if the centrifugal switch doesn't connect the M1 and M2 red wires, the dryer will not heat at all.
You will need to make sure to watch the videos a few times until you know how to fix a not heating Whirlpool 27 inch gas dryer. Never assume that a part is bad without checking it and make sure it is bad before replacing it.
Another thing that you need to do is to learn how to check, remove and install the parts before starting to buy replacement parts.
Make sure that the company that you buy parts from give you a good return guarantee in case that you may need to return any parts.