Trane xe 90

leaking

I have a trane xe 90 that flashes 4 - thermal protection device, I had a what I think is a hack here replace the motor , thermostat , and now he says I need a new furnace there is a leak but my digital Co meter with Peak Read function reads Zero, he replaced the sensor module to the left of the blower motor, also besides replacing the blower motor. He says furnace is shot but I don't believe he knows what he is doing. He measured gas at 7 columns before gas valve and 3.5 after. It's near zero in Chicago

Paul S_3

well

Obviously he is having a problem diagnosing the furnace. "thermal protection"could be the high limit , spill switch, or roll out switch.high limit senses the temp near the furnace heat exchanger, what can cause it to open it's circuit is a few things, but lack of air flow is a common cause for that.spill switch protects you in the event of a chimney blockage etc. preventing CO from entering the home.roll out switch is located near the burners and it trips when the flames roll out or when the temp near the burners exceeds it's limit.my recommendation is that you get a real professional who knows what he's doing.someone had to verify WHAT safety is turning the furnace off, and when they do they must FIND the source of the problem, at no cost allow any technician to"jump out"or bypass any safety. Carefully watch what anyone does, there's allot of technicians out there that think a switch is at fault just because it's opening the circuit but it's actually doing what it's supposed to. Then you must have a combustion test done, to insure that the appliance is properly firing, if they do not have a digital combustion analyzer then do not hire them.good luck Paul S (p.s.....more than likely your furnace does not have to be replaced, most problems can be fixed, that it's a scape goat for most companies when they cannot figure out a problem)

John Mills_5

Intell board

If that has the Intell-ignition board, flashing 4 with no limits open is a common failure of the board. Replacing the board solves it which apparently he did. But why the blower motor? Was it really bad?



Those are great furnaces. Rare to lose a heat exchanger but can happen. HX has a lifetime warranty so lots cheaper to replace it than new furnace. We're more likely to find cracked secondary header than crack in the primary cells of them.

unclejohn

Wasn't That

Also the furnace that had faulty connections on the yellow wires to the limit switch? Seems like it was the 9 wire plug that was the culprit.

drhvac

limit

I agree you definately need someone who knows what they are doing. If your furnace is running to hot and going off on limit, that means your not getting rid of the heat it is trying to deliver to your house quick enough. Did anyone do a temp rise across the furnace, it should be between 40 - 70 degrees? Is the evaporator coil blocked up? I get this once in awhile especially with customers who have allot of dogs or cats, the hair builds up over time and restricts the air flow. It dont think your having any problems with the rollout limits because they have to be manually reset.

leaking

Trane xe 90

Thank you all for the help, when airflow was mentioned and Exhaust, we checked the exhaust line and found it sagging with water in it, we fixed that and its fine now. So yes he was a parts changer, 30 years in business and never spent the time to learn as you guys have , thanks