Pressure Switch Circuit Malfunction

G7 furnace not lighting, but don’t see a fault code?

Knowing something is wrong, but not being able to figure out the problem can be more than frustrating for even the most experienced tech. Today, we’re going to talk about a particularly frustrating problem – when a G7 high-efficiency furnace will go through the pretrial for the ignition sequence, light and then stop for no apparent reason. No fault codes. No indication of the problem.

Did you know that this could be an indication of an open pressure switch?

In the event that the pressure switch circuit opens after the furnace has already been lit, the board will not instantly produce a fault code concerning the pressure switch. It will attempt to close the switch by continuing inducer operation.

If the pressure switch still does not close, it will put the furnace into a brief standby mode and restart. If the pressure switch still does not close after restarting, then and only then, will you see the fault code. From there, you can begin troubleshooting the potential issue with the pressure switch.

It’s important to keep in mind that circuit board codes cannot tell  you a switch has FAILED. the code is merely indicating whether a circuit is open or closed. Knee-jerk pressure switch replacements do not have a high success rate. Make sure you are troubleshooting the reason behind the open or closed circuit and not making hasty replacements.

Remember, the answers to many of the problems an HVAC contractor may face on a day-to-day basis can be found on EdgeTek. No need to wait on hold, get the answer immediately!

What other technical troubleshooting tips would you like to hear?

***NOTE:ONLY USE IF YOU ARE AN HVAC CONTRACTOR. If you are a homeowner trying to dip your toes into the DIY pool – STOP. Serious complications can arise when HVAC installations, repairs or maintenance are performed by someone who is unfamiliar with heating and air conditioning equipment. Drop the wrench, pick up the phone and call a professional.

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