Bypassing Blower door safety switch

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Old 10-08-19, 05:27 PM
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Bypassing Blower door safety switch

there is a ten year old thread on this; let me summarize. When you take the blower door off a furnace there is a spring loaded shut off switch. Over time the blower door will not have enough pressure to keep this switch on when door is in place. Blower/furnace will not turn on.

It's a dumb safety mechanism. When you take off the door you could have simple lever off and on switch. How can I replace this dumb pressure switch with a smart on/off switch?
 
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Old 10-08-19, 05:32 PM
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Welcome to the forums.

It's a dumb safety mechanism.
No... its a safety mechanism that keeps dumb people safe.

Smart switch..... no. It's not like this door gets opened all the time.
I think I've only had to change one safety switch.
You could change your switch if it's not working right.
 
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Old 10-08-19, 06:25 PM
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Return air under negative pressure exists behind that door. If removed, the possibility exists of pulling the surrounding area into negative pressure and pulling products of combustion into the living space.
There is no “smart switch”. Usually if one of those doesn’t close it’s because the bracket is bent in.
It’s a very simple and proven design. No reason to overcomplicate things.
 
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Old 12-05-19, 06:22 PM
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Angry How to bypass furnace door safety switch

My Carrier gas furnace will run a complete heat cycle (thermostat set to 70, furnace will heat to 71, and then stop as expected). Right after it stops, the red LED on the circut board will turn off, making it appear that there is no power going to the circuit board anymore.

At that point, to get heat later on when the house cools down, I have to take the furnace door off, mess with the door switch several times after turning the power switch off, then turn the power switch on and press the door switch a few times, and then the heat will come on.

I would like to bypass the door switch to see if the door switch is the problem or not. How do I safely do that?
 
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Old 12-05-19, 06:38 PM
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Welcome to the forums.

Try this. Don't mess with the door.
Turn the service switch off and back on instead and see if the system restores.

If you're sure it's the safety switch...... there will be two wires on it. Connect those two wire together.
 
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Old 12-09-19, 09:50 PM
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How to bypass furnace door safety switch

Turning the service switch off (the one that looks like a light switch) and then back on did not help. But, what did help was close. If I push on the light switch plate with my hand, and then let go, that seems to start the furnace again. I've done this 2 days in a row with success. So, that makes me think it's either a loose wire in the switch or a bad switch. I'm going to buy a new switch, and then take a look inside of the box that the existing switch is in to see if it looks like a loose wire. If not, I'll try the new switch. Thanks.
 
 

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