I just love all the "experts" weighing in and criticizing this mans work, especially the one clown who claimed his boss wants everything diagnosed within 15 minutes or you arent doing it right. Whatever. Weve all made mistakes and have missed obvious things, no two calls are really ever the same because you dont know the history of the units and how many hacks have been there before you. Vid watchers need to relax and appreciate the work that goes into making a video for us to enjoy.
I don't think he knew enough about his job I had been servicing heating units similar for over 25 years The time he wasted cleaning these Ignitors at the beginning he did say low Pilot flame That is the first thing you rectify By checking the MillivoltsI thermocouple or Thermopile then 90% our problems are solved Before my Retirement I was a Industrial Service Technichian the Time he wasted on cleaning the Spark ignitors it would have been cheaper to just put new ones in Labour = time Time =Money
If it's shutting down on flame sense the 24 volts to the module will not change. If the limits open they will break the 24 v input.Check first to establish cause. After cleaning sensor remove and clean pilot line, of rust spiders etc without proper flame how can it sense properly. You need to start establishing cause and effect and stop hunting in circles. Treat the units problem as a wiring diagnosis. Start somewhere and go threw the chain of cause and effect and find the problem. Jumping around just slows you down and scrambles your thought processes. 40 yrs in the trade and training lots of newbees, has proved that a plan of attack and following the cause and effect chain is always faster and less stressfull. Good Luck
Also remember that "flame" is a very poor conductor of electricity. The flame rod is normally fed 120V AC. As the 120V is "conducted" through the flame the electric current is changed from 120V AC to 12V DC. And since the flame conduction is known as a half way rectifier, the circuit board is looking for a milivolt DC pulse. If the curcuit boar cant read that through it's ground then flame cuts out at about 3 sec - Hope this helps you. Hard lessons
On those old york/luxaire units I always pull the burner first , to clean the tubes and look for spider webs in the pilot orifice, and always change the flame sensor. On some models there is a high limit directly opposite side of the burner panel.
Pull the burner rack clean entire burner assembly and support bracket u don't have enough ground area gets worst when cabinet heats up look for 2to 4 microamps by the way good job u test don't guess
Any outdoor unit is subject to wind distortion of the flame when the panel is off. You should replace the panel when checking operation. Could easily disrupt flame rectification. Exterior units especially prone to bad grounds. I agree with suggestion consider secondary ground wire and really scrub the ground surface on the chassis. Agree you can use a megger to test flame rod insulation.
I live in New Hampshire, and these York units are very common up here. I've found that when the heat is off for the summer, spiders will find a home inside that pilot crossover tube and screw everything up. What I typically do is pull the whole burner assembly out and take the pilot tube apart and blow it out. Check the pilot orfice, make sure it's not clogged. Clean the flame sensor while the burners are out. Pulling the burner assembly is quick and simple. Just a union and a couple screws. Put it back together and watch it fire off. May need to adjust the pilot pressure a tad. And 95% of the time the heat fires off for me after doing this.
