# Harman diagnostic tool / Accentra problem



## jimmie ray (Aug 26, 2010)

We just got the diagnostic tool from Harman, which plugs into the control board for troubleshooting. No instructions provided, and I can't find the tuitorial that is supposedly available on the internet. We do have a problem Accentra insert job, that the tool was recommended for - soooo:
1- Anyone here familiar with the diagnostic tool, and do you have instructions?
2- The Accentra's convection blower runs infinitely after shutdown. The ESP probe (which would be a likely cause, if not functioning properly) was changed. There was also an odd sequence of operational problems, parts failures, and swaps that I was not involved with, but did get a history of. I believe a shorted ignitor wire led to 2 fuses being replaced, and then the control board (dip switches supposedly set correctly - I need to confirm this). Since the ignitor problem wasn't found until the last visit, I think the replacement control may have been again affected - unless the fuses 100% protect against this? The Harman tech support guy gave so me many things to check (including the pressure switch, which would seem to only tie into the combustion blower operation?), but said the diagnostic tool would pinpoint the problem quickly. On top of all this, certain wires were disconnecting each time we slid the unit back IN place - but that is now corrected. Any thoughts? Thanks in advance!


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## Delta-T (Aug 26, 2010)

recalling from memory here...
1st menu will show Circuit board type (part #) and current operational procedure (startup, run mode)
2nd menu shows ESP temp
3rd menu is voltages to motors
4th menu is dial settings and room/stove temp mode along with room sensor reading.


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## Delta-T (Aug 26, 2010)

if the ESP probe was replaced there is a chance that the #5 dip switch is in the wrong position, if the original probe was red, and the replacement is black (or vice versa).


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## jimmie ray (Aug 26, 2010)

Delta-T said:
			
		

> recalling from memory here...
> 1st menu will show Circuit board type (part #) and current operational procedure (startup, run mode)
> 2nd menu shows ESP temp
> 3rd menu is voltages to motors
> 4th menu is dial settings and room/stove temp mode along with room sensor reading.



Not very complicated - I guess that's why they figure no instructions are necessary... But would the diagnostic tool indicate an operational problem with the control board itself?


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## Delta-T (Aug 26, 2010)

not directly, but it will show erroneous ESP reading, say if you know the room is about 70 degrees and the probe reads 150 degrees, you know something is wrong. If you have the stove in off position but the mode says running, then you know something is wrong. If volts are being sent to motor but it doesnt turn you can trace everything back. it wont tell you the nature of the problem, but it will tell you what the board is doing or thinks its doing, and you just have to bench that against what you've told the board to do.


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## jimmie ray (Aug 26, 2010)

Delta-T said:
			
		

> if the ESP probe was replaced there is a chance that the #5 dip switch is in the wrong position, if the original probe was red, and the replacement is black (or vice versa).



This is a newly installed stove, so I would think the replacement of the ESP probe should not have been necessary. I believe the convection blower directly responds to the ESP probe temperature, so it was probably deemed the most likely and easiest part to replace, at the time. I do have to confirm the dip switch settings, now that I have a spec sheet that shows the proper position for each model stove. It may be as simple as that, but I want to be prepared to resolve this in any case. Do you know if the fuse protects the control boards logic integrity, under the conditions that have occurred at this job? Thank you again for your guidance!


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## Delta-T (Aug 26, 2010)

usually, if the board gets attacked by a power surge, the board dies. fuse usually only blows when theres a short and excess amps are drawn (like ignitor wires exposed, or crimped in the mounting bracket), and then the board's logic is usually intact. i say usually, because i've seen just about everything you can imagine and sometimes the identical thing happens to identical stoves and different problems arise. I would point to esp probe, except you didn't mention the combustion fan running continuously. That should be the last thing to turn off at 90 degrees (ESP reading), any chance that the wiring is mixed up? Convection blower should shut off at 165 (esp reading).


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## jimmie ray (Aug 26, 2010)

Delta-T said:
			
		

> not directly, but it will show erroneous ESP reading, say if you know the room is about 70 degrees and the probe reads 150 degrees, you know something is wrong. If you have the stove in off position but the mode says running, then you know something is wrong. If volts are being sent to motor but it doesnt turn you can trace everything back. it wont tell you the nature of the problem, but it will tell you what the board is doing or thinks its doing, and you just have to bench that against what you've told the board to do.



The ESP probe sends a resistance reading to the control, which then correlates a temperature to that reading. So I would still have to check the ohms directly from the ESP probe wires. But when I asked the Harman guy for the resistance spec at room temp, it was higher than the scale of my meter reads - so I couldn't follow through on this step. However, I would lean more toward the control board not correlating the right temperature to the ESP probe resistance, than the probe itself being faulty.


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## jimmie ray (Aug 26, 2010)

Delta-T said:
			
		

> usually, if the board gets attacked by a power surge, the board dies. fuse usually only blows when theres a short and excess amps are drawn (like ignitor wires exposed, or crimped in the mounting bracket), and then the board's logic is usually intact. i say usually, because i've seen just about everything you can imagine and sometimes the identical thing happens to identical stoves and different problems arise. I would point to esp probe, except you didn't mention the combustion fan running continuously. That should be the last thing to turn off at 90 degrees (ESP reading), any chance that the wiring is mixed up? Convection blower should shut off at 165 (esp reading).



It's funny I read someone here suggested a live chat section - I can't even keep up with this one thread!
Yes, the ignitor wires were crimped, which blew 2 fuses. If the control board's logic should not be affected by this, then the dip switch settings seem very likely to be not set properly. The combustion fan seemed to shut off properly after a while, but the convection blower reportedly ran for a full day. I will check to see if the leads are interchangeable. Another thing to consider is how hot this room stays at - all this troubleshooting has occurred over a brutal summer, and maybe he doesn't have AC...


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## Delta-T (Aug 26, 2010)

very difficult to read ESP with run-o-the-mill multi meter without knowing the exact temp and having a grid of resistances in mf for the entire temp spectrum. The diagnostic tool is the best way to check for ESP function. I have yet to see a board give a faulty temp reading when the ESP is working correctly. I dont often see firmware glitches, just total failure of the logic system. 

If the combustion blower runs forever, its probably the ESP or the #5 dip switch, if the distribution blower runs forever you either have the 2 blowers swapped somehow, or the board is toast. That would be my opinion. Ran this by my associates and.....we all say weird. YOu did not do the original services? You are "cleaning up" after someone else? Double check the wires for the blowers, i totally suspect they were swapped.


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## jimmie ray (Aug 26, 2010)

Delta-T said:
			
		

> very difficult to read ESP with run-o-the-mill multi meter without knowing the exact temp and having a grid of resistances in mf for the entire temp spectrum. The diagnostic tool is the best way to check for ESP function. I have yet to see a board give a faulty temp reading when the ESP is working correctly. I dont often see firmware glitches, just total failure of the logic system.
> 
> If the combustion blower runs forever, its probably the ESP or the #5 dip switch, if the distribution blower runs forever you either have the 2 blowers swapped somehow, or the board is toast. That would be my opinion. Ran this by my associates and.....we all say weird. YOu did not do the original services? You are "cleaning up" after someone else? Double check the wires for the blowers, i totally suspect they were swapped.



I am indeed on "cleanup" duty, but let's not dwell on that aspect... The one visit I made revealed wires were very prone to disconnection as the unit was slid back in place - so I thought correcting that was the final answer. Harman gives a precaution in their manual about wires disconnecting as the unit is slid out, which is much easier to catch. The room sensor wires seemed the most vulnerable to disconnecting, and maybe the blower wires were compromised at some point, too. But if the blowers were swapped, I wouldn't have seen proper operation during startup - as the combustion blower would have been delayed in coming on, and the convection blower would have come on too soon?


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## Delta-T (Aug 26, 2010)

jimmie ray said:
			
		

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Yes indeed, that sounds correct. Very strange indeed sir, very strange. Between the 4 of us here (all techs, to some degree or another) we have never seen the dist blower run like that. Many times have seen the comb blower run like you describe. Color me puzzled. WHen you figure it out, and I faith that you will, please let me know what you find. I do like a good puzzle.


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## jimmie ray (Sep 13, 2010)

Delta-T said:
			
		

> if the ESP probe was replaced there is a chance that the #5 dip switch is in the wrong position, if the original probe was red, and the replacement is black (or vice versa).



Just accessed the Harman website dealer login section, where their technical bulletins on this are. I'll have to go back to see what control and probe are installed (both were replaced). It might just be incompatibility or a dip switch setting, but this was never discussed in phone calls to their tech service. I also now have a newly installed Harman XXV job with a combustion blower that doesn't shut off for over 1 hour after the fire is out, where none of the parts were changed. Still waiting for some sort of instructions for the diagnostic tool, which they promised to send?


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## Delta-T (Sep 14, 2010)

jimmie ray said:
			
		

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remember that the esp tells the comb blower to run until it reads below 90 degrees, so if that XXV was fired up on a warm day it could take a long time to cool off. i see this relatively frequently after the summer cleaning and fire-up. If its 80 in the house, it could take forever to get below 90.


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## jimmie ray (Sep 15, 2010)

Delta-T said:
			
		

> remember that the esp tells the comb blower to run until it reads below 90 degrees, so if that XXV was fired up on a warm day it could take a long time to cool off. i see this relatively frequently after the summer cleaning and fire-up. If its 80 in the house, it could take forever to get below 90.



You don't personally fire-up the unit and wait for a proper shutdown, unless there was an operational complaint, do you? I had a hunch about the warm room / day thing, but you're the first to confirm that possibility. And trusting an irritated homeowner's report on which blower wouldn't shut off isn't helping, either. We've been waiting for the cooler weather, to prove there actually is a problem - should know soon! Why they chose 90* F shutoff, instead of maybe 110* F (given the tolerances of resistance sensors) is beyond me...


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## Delta-T (Sep 15, 2010)

indeed, fire up the unit, wait for run mode, shut down unit, though I dont stick around to watch it get to complete shutdown, thats why I get the call 1- 1.5 hours later that says "my stove is still on". If I didn't fire it up and watch the process (with DDM hooked up) I guarantee that something will go wrong, like the ignitor wont fire up or something, and I'll be back at that persons house on Oct 6th to check on something I should have noticed, or inspected when I was there before. nothing worse than having to go back for something silly. Just plug in the DDM, look at the ESP temp, if its over 90, then its all working fine, if its below 90 and that comb blower is running, something is amiss.


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