Day and night - N9MSB0802120A1. Roughly 6 years old.
So my limit switch keeps tripping. I used a multimeter to verify that it reads 24v when it trips. I also tested continuity and it was good. I removed the limit switch and used a jumper to keep the furnace running while using a meat thermometer to check temperature in the port. Temperature never came close to the 200F specified on the limit switch. So I replaced the limit switch and it's still tripping. Air filter brand new and still trips if removed. Blower is 1 year old, furnace 6 years old. All registers are open and should be clean. Unfinished basement so only registers on upper levels. No kids or pets that might stuff something in the registers. There are no dampers either. AC unit was replaced last summer, so the coil should be relatively clean.
What else could it be? Evey time a tech comes out, they suggest something different with a huge expense. Kind of like going to a jiffy lube and being up sold a cabin air filter replacement for 75 bucks.
Moreover, it never locks out on me. And I only seem to have the issue when bringing the house to temperature in the morning. Say from 65 to 70. It runs fine during the day and night to keep things at temperature.
So my limit switch keeps tripping. I used a multimeter to verify that it reads 24v when it trips. I also tested continuity and it was good. I removed the limit switch and used a jumper to keep the furnace running while using a meat thermometer to check temperature in the port. Temperature never came close to the 200F specified on the limit switch. So I replaced the limit switch and it's still tripping. Air filter brand new and still trips if removed. Blower is 1 year old, furnace 6 years old. All registers are open and should be clean. Unfinished basement so only registers on upper levels. No kids or pets that might stuff something in the registers. There are no dampers either. AC unit was replaced last summer, so the coil should be relatively clean.
What else could it be? Evey time a tech comes out, they suggest something different with a huge expense. Kind of like going to a jiffy lube and being up sold a cabin air filter replacement for 75 bucks.
Moreover, it never locks out on me. And I only seem to have the issue when bringing the house to temperature in the morning. Say from 65 to 70. It runs fine during the day and night to keep things at temperature.
source https://hvac-talk.com/vbb/showthread.php?2224097-Limit-switch-keeps-tripping&goto=newpost
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