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Old 02-04-2018, 03:37 PM  
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Default Pressure sensor issue?

I have an airtemp (aka nordyne) vg7sd gas furnace in an upflow configuration.* I began having issues about a month ago when my HSI failed... Easy fix, but in the process I noticed two other issues..

A condensate line from the inline condensate drain to the top of the secondary heat exchanger drip pan was missing.* I procured some tubing and installed, just as shown in the furnace installation manual.* Pictured, and drawn in blue.

Also, I found that there was a gap where the flue pipe connects to the inline drain where condensate had been dripping out.* I cut a very small section of flue pipe out, and installed a coupler so I could get the flue pipe closer to the inducer motor, and properly seated into the inline drain.* Upon restarting the furnace I used a soap solution and confirmed no leaks.

Several hours later it was found that the control board displayed a pressure sensor fault.* I traced this to the pressure sensor on the condensate drip pan.* Verified j-trap wasn't blocked, but had the proper amount of water in it.* I carefully confirmed operation of the pressure switch using an ohm meter.* I confirmed the vacuum tubing from the switch to the drip pan was leak and clog free.* I ended up reconnecting the tube to the drip pan and blew into it.* When I reconnected everything the furnace started up and ran properly.* By this point I had also removed the tubing from the inline drain and replaced the caps that were there previously.

Ever since then I have intermittent issues where a pressure limit fault appears and the furnace locks out.* I cleaned all condensate lines, removed the inducer motor and verified the collector pan is free of debris and even replaced the pressure switch in case it was somehow getting stuck.* I'm now at a complete loss....

Every time the issue occurs I can fix it by blowing back into the condensate pan, yet I still notice this issue every 3 days or so.* If I don't touch the furnace it will eventually come out of lockout on it's own.*

The only other thing I can think to do is replace the inducer pressure switch... I haven't been removing that switche's line before blowing back into the condensate pan, and I guess I probably should be doing that...

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Old 02-06-2018, 11:23 PM  
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Old 02-07-2018, 12:18 PM  
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As best I can tell, it appears to run on some form of electricity. Be patient and I'm sure someone who knows these things will be along.
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