View Full Version : Lennox Gurus

08-20-2011, 09:53 AM
Need some help with Lennox L serries rtu. These units are networked with a NCP 1-1 controller. Units were hit by a power surge and 3 of the ICM boards were damaged.

The old boards M18 were a version 5.25 and the new ones are version 6.06.

I have remote air sensors on each unit with the override switch.

So here are the problems that I am having,

2 units are working when the overide button is pressed although sometimes it is erratic. The inducer motor will come on for aprox 10 seconds then shut down then a few seconds later the compressors will fire and all is fine. Lennox has not been able to verify that this is a proper operation of the system. The old boards did not do this.

Other times it can take 2 minutes or longer before the compressors will come on. The old boards bring the compressors on without delay when the over ride button is pressed.

These are not major problems but have not been able to get Lennox to verify this is normal operation and customer would like to know that this is proper.

Have another unit that the over ride will not work at all. The over ride switch is working, the inducer comes on for 5- 10 seconds and shuts off but the compressors will not fire. The NCP does not show that the system is in over ride like the other units do. Note that the unit operates fine when the NCP is programmed to have it on. However this is not acceptable to the customer as the rooms are used at random and thy want to be able to use the over ride feature.

I have had local Lennox rep out twice on this system and he has not been able to help with this problem. The rep is a nice guy and has tried to be very helpful. He has told me that there is a program that they can hook a computer up to this system and look at the settings and see what is going on but he never brings it with him. I get the feeling that him being an older guy that he might be gun shy when it comes to computers.
Does anyone know about this program? Is the program available from Lennox and the cost of it?

Any local Lennox reps that can help? I am in St Louis, MO

Thanks, Gary

08-20-2011, 10:17 AM
I don't recognize the issue you are having but I have worked on a lot of the L Series RTU. You need L Connect software to program or troubleshoot those modules.. Is that the software you are talking about? I didn't think they came programmed out of the box for every RTU, especially if you have reheat and dehumidification.

08-20-2011, 10:35 AM
Yes that is the software I would need. You can program these boards without software but you need to do it by going thru all the settings at each board and there are a ton of them. However the system should still work like i want it to using mostly the default settings as the other units are working by pushing the over ride control. Did you have to purchase the program ? And I believe there is a special connector needed to do this by computer?

08-20-2011, 10:44 AM
Yes, you purchase it from Lennox, it should come with the cable and connectors. If I remember right mine connects to the 9 pin on my laptop. I have never tried to set up one of those boards without the software, most of the L Series we have are loaded with all the dehumid and reheat options, so there are a lot of variables to set. I cant believe a field rep would show up without it.. Once you have the program it makes the job go soooo much easier in troubleshooting and testing. I don't remember the price but I remember it wasn't wallet breaking like most OEM garbage.

Once you get it load up and back up all the RTU you work on so if they crash you will have a back up.

08-20-2011, 09:58 PM
Thanks for the info Zero. Got the unit up and running today. The new board was bad. Replaced it and now all good.

Still need some answers from Lennox about the inducer running when the over ride is set.
I think this may be the way the new boards operate to try and cut down on heat exchanger condensation. The big problem with that is it shows as an error code on the NCP.
There have been problems with these units having ghost error codes mostly in the heat cycles.