Maybe reversed polarity? I see it all the time on low voltage comm stuff, not sure if it applies to what you have though.


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Thanks heatingman.
That was the first thing I checked. Theres a Line1, Line2, and Line3. Line3 is communication. It's a 208/230vac equipment. The wires leaving the outdoor to the indoor is a black for line1 and a red for line2 and white for line3. At the indoor it's the same order. I will do a conductivity test one the wires to make sure but from the test I made on the DC communication it tells me that the outdoor is sending a signal the indoor is sending one back (checked the line3 wire when it was disconnected from the teminal block. So that tells me the indoor board and wire is good. And the 240vac is at the indoor. It was a long day after that. What was a 2-3hr job became a 6hr job. I was to pissed off to keep checking.

 

All comm systems require 2 - wires - either 2 physical wires, or 1 wire and a ground path. (May also multiplex signals on one of the other 2 wires)

Perhaps a connection is not made well somewhere, a ground path is missing or corrupted or there was a wire change somewhere.
With 2 indoor units, there would have to be a wiring junction point. That would definitely be something to look for.


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i had a similar issue on a quiet side unit,not communicating ,wrong voltages etc . this was a new installation 2months old but using existing wiring .to test my theory of a bad wire ,i run a new temp wire 80 ft or so from indoor to outdoor, taped to doorway,s etc. unit immediately worked ,Run new wiring ,which did not please the customer, as this had to be run on finished surfaces although professionally installed ,but it resolved the issue.. if you can not resolve other ways may be worth a try

 

Thanks Cooljim.
I guess you and heatingman are on the same page. I may have to do that and run a temp wire to see what happens. This is a roof top mounted unit but they have good attic space. If it works with the temp. I may be able to replace the wire all in the attic space. If not it is what it is. Oneway or another. I just find it hard to belive it's both wires. Both indoors are giving the same comm. Error. And they are seperate runs to unit A and unit B.

 

Thanks again.
You are right. This unit is a 1 wire (line3) and ground path. There are 2 sets of 14/3 with ground romex. One going to unit A and another to unit B. I did my communication check between Line 3 on the teminal block to ground and got 60-130vdc. So that tells me that the board signal to ground is good. On that same ground wire which goes to unit A to the wire that goes to L3 on the terminal block there was 60-130vdc as well. I am going to recheck all the wiring again. I really can think of any thing eles. Seeing how there are seperate lines to each indoor there is really no meeting point.

 

How about an actual earth ground. Electronics can be very sensitive to a missing earth ground. Check voltage between the ground wire and the case of the unit, and again to the actual ground.


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I'm with you. I never checked the actual ground coming into the system with Line1 and Line2 from the disconnect. I did connect it to the chassis and that same chassis is the ground screw for unit A and unit B wire sets. I figured I had a good ground seeing how my comm. Was there from line3 to ground. I did notice there was an outlet mounted on the pad for service. It was not getting power as I tried to use it for my recovery machine and vac. Pump. So I ran an extension cord from inside the home. I wonder if it maybe related. However it's a 240vac system. No neutral so I'm not sure how they would get 120vac to that outlet if it connected to the circuit that the unit is one. Unless they are using the ground on the circuit as a neutral. I hope not but you never know.

 

Ok, I may be over thinking this but I guess that's what we do in troubleshooting sometimes. The customer stated that the system was working fine. They had a big storm roll through which caused a power outage. After power was restored they noticed the system was not working. Along with a few of the neighbors. However they had package units and we're minor issues. If lightning hit a ground somewhere or surge is it possible it traveled the ground wire of the home and went through the communication wire with fried the board on the orginal seeing how I did not have communication from the orginal board and the contorller board was shot. I did not see any burnt marks on the board it's self however it was bad. Could this have affected the ground for the entire home? Maybe they did use the ground as a neutral on that outlet and seeing how the ground maybe lost it is no longer working as should. If that is the case I would not see DCV communication through the wire it's self to ground. Right? Just thinking out loud

 

If earth ground was corrupted, that would kill that service outlet if thats how it was wired, and may also effect your communication - seems as good of a starting point as any. Hopefully it works out for you.

Not sure about the lightning, but power that high does not follow the rules of electricity the way we would expect.


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Thanks. I'm heading back there Monday. That way I can get Friedrich on the phone as well. I will let yall know what happens.

 

Good luck


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Ok, so here's what happend. I checked it all out and still same results on the communication readings. I called Friedrich and they told me that with there's readings I should not see a communication error. Yet there was one. They told me that the only thing I could do is replace the solid 14/3 with strained 14/3. I tried that on the outside for test and still same thing. They then told me to just try and swap L1 and L2 at the indoor. Even though they are color coded you never know. I did it on one indoor and BANG! It worked. No error system works as should. Happy customer happy contractor. Hope this helps someone else... Thanks all for the help. And as far as that outlet goes GFCI was tripped in garage.

 

There you go. A polarity thing - my first thought. Glad you got it. Nice work!


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I know. You were on the money. Who would have thought. L1 was black on the outdoor and indoor. L2 was red on the outdoor and indoor. I just wired it up like it was before. However, I did notice on the old outdoor the wires going out the board to the terminal block were swapped. I did not think much by it seeing how it came from Friedrich this way and power is power. L1 L2 it's 240vac anyways. I left the indoors alone and did the wire swap at the outdoor board. I guess the communication goes back on L2 from L3 so it does matter. Anyhow lesson learned. Lost 3 hrs on that.