Thermador Range burner Not Working

Thermador Model #PRDS364 A high end gas range began having a problem when the front left burners would not ignite. The front burner are the most used and with a family of eight. It was time to call for service.

When the knob is turned to the ON position the spark module begins the ignition process by a spark, A click can be heard but No flames and No Gas could be heard at all. This is the the only burner that would not work all others work great.

The surface burners on this range use valves connected to a manifold to control gas flow to each burner. A micro switch connected to the spark module for ignition, All four igniter spark when any one of the four mirco switches are turned on. Only the one with gas supplied will ignite.

The gas will flows into the burner assembly where it will ignite with assistance for a spark from the igniter electrode. when the valve increases the gas flow and the burner flame will increase, while turning it down will lower the flame.

This range has two burner that have a simmer mode. These burners have the ability to go from a 18,000 btu/h output to 375 btu/h, a very low flame for melting chocolate or cheese. This low flame is achieved by a secondary solenoid valve. Low simmer it is not controlled by the main gas valve. but from a potentiometer and simmer control board to keep this low flame glowing.

When the knob is turned on, The simmer control sends electricity to a solenoid valve to open the main valve will turn on.When the knob is turned to simmer the simmer control shut off the main valve and the low output valve will turn on. The output will vary depending on the position of the shaft as it rotates the potentiometer. The potentiometer changing resistance is used by the simmer board to maintain the gas flow from the secondary valve.

With only burner were not working I first checked the solenoid valve for community. As solenoid valves are a common point of failure. both solenoid valves had community. Now it was time to check voltage. there valves use need 110 VDC to open. With only 60VDC I suspect the it was the Simmer control pn#497235 the simmer control comes in a kit with two potentiometers as they should be changed as a set.

I replaced the two potentiometers and simmer control that is located behind the spark module under the top to the far right in the back. With the parts replace all burners where working great. Now she can boil large pan of water for spaghetti and melt chocolate for s’mores.