The heat from my Trane XE 70 stopped working. When I turn the thermostat on, I get the initial click from the relay but no flame and no click click click click........ So I dug up the schematic (haven't looked at a schematic since the Air Force, 30+ years ago) and I think I found a voltage issue at the pilot relite (White Rodgers 5059-41), which is getting 24V at T1 but nothing at T2. It seems that the 24V that should be going to T2 should be coming from the gas valve but I'm not sure. Any suggestions would be helpful. Thanks in advance!
Put the high voltage lead back on the module. Measuring there will destroy a meter.
You need to have 24vac on the two power tabs when the thermostat calls for heat.
It looks like when the module gets power.... so does the gas valve.
You should post a picture of the wiring diagram or the full model number of the furnace which is found on the ID plate on the side wall near the burner.
Blue is common. There should be no problems with the common line.
White is the W/switched 24vac power.
Clip one meter lead on the common/blue line. 24vac is applied to W(1) from the thermostat.
Check for 24v on both sides of safety stat 3.
If ok.... check for 24v on both sides of fusible link 4.
If ok.... check for 24v on both sides of fan/limit switch 5.
If ok.... check for 24v on T1 of igniter module.
If there it should also be on the gas valve 7.
After further digging (and realizing a forgot A LOT about A/C circuitry), it appears that the voltages on the pilot relite are supposed to be 0V (common/neutral) at T2 and 24V at T1. So does that mean the pilot relite module is bad? If I pull off the orange wire off the pilot relite module and try to read the voltage off the lead in the middle of the blue plastic piece, should I get a high voltage reading if it's good?
I appreciate you taking the time to draw that up for me. Thank you very much! I have 24v at all the points you said to check. No spark. Coincidentally, I already pulled off the igniter module, thinking it might be the issue. I may have jumped the gun doing that but it's a learning experience and I'm ok with that.
When you connect the spark module it creates sparks from the high voltage spike to ground.
I usually use an alligator clip lead connected to module ground to check for spark.
I pulled the ignition module out and wired up some leads to it. The first couple of times was very faint clicks for a few seconds then nothing. Then absolutely nothing was happening after a few more attempts. I came back a few hours later and tried again and it started working! Somehow, it must have "woke up". Put it back in the furnace and all is well again!
Hello,
Thanks for taking the time to read this.
Problem:[indent=40px]Pilot turns off when gas valve shuts off. In other words, when the thermostat trips off, the gas to the heater turns off, and the pilot goes out too. Not every time, but maybe 80-90% of the time. Pilot flame size and TC coverage in image attached. Pilot stays on indefinitely (at least 5 days) without turning the thermostat tripping on/off.[/indent]
Furnace details and things I've tried:
[list]
[*]Cozy DVCF 403B-H
[*]Natural Gas
[*]Inlet pressure is 3.5" W.C.
[*]Replaced the Thermocouple
[*]Opened up the pilot valve more.
[*]Removed, tightened, and replaced all electrical connectors on the gas valve, gas switch, limit switch, and auxiliary limit switch
[/list]
Things I'm considering but haven't done yet:
[list]
[*]clean out the pilot orifice and gas line. I'm not sure this is necessary given how large the pilot flame is.
[*]replace the gas control valve
[*]Opening the gas control valve to investigate the internals.
[*]find and fix drafts. it seems like there is a significant amount of wind or pilot flame motion when the heater turns off. It takes maybe 5-10 seconds for the pilot to stabilize. I wouldn't be surprised if the pilot just blew out.
[/list]
Any ideas for what might be causing this issue? I'd rather not spend 300$ on the control valve or $1500 on a replacement furnace. Especially if the issue is something related to drafts.
[img]https://cimg8.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/pilot_over_tc_524bc94dd052b66328ebc676aae32972eac74547.jpg[/img]
Thank you!
Joe
12-05-22, 05:20 PM
