ncm-300 issues

[bham]

I have an NCM-300 unit with honeywell thermostats. If their is a large temperature difference between the actual temperature and the set temperature when the thermostat is set to auto & cool everything seems to run normally. If there is a small temperature difference (i.e. the unit is turning back on after the actual temp. falls just below the set temp), the fan will turn on for a few seconds and stop. It will do this continually until the temperature difference increases (or so it seems). I have also noticed at times that the compressor unit will rapidly cycle at random intervals.

AHS sent out a contractor and after what seemed to be his third "guess" he said the unit needed to be replaced. AHS will not replace the unit stating it is a "damper controller" and is not covered.

Any suggestions or is there a way to test if the board needs to be replaced?

Thanks

Also, with the thermostat set to "system off" & "fan on" the fan will act the same. It will cycle every few seconds.

[Pcyrana]

I would not replace the board right away without further troubleshooting.
Would you be able to give our tech support line a call so we can try to determine what the problem could be?
If not you can start by answering these questions.
When your fan is cycling on and off what is the fan LED doing on the Zone Panel?
Are your thermostats Fan switches always set to the Fan "ON" position. If so, do you want the fan to be running at all times.
When the compressor randomly cycles, is the Compressor light on the board cycling on and off as well?

Thanks,

[bham]

i am not able to call tech support while at the house until monday. i work 6-6

I don't recall if the fan LED was cycling on and off. i have seen the fan LED stay on after the fan turns off. At that point the thermostat set point had not been satisfied. The fan turned back on after about a minute.

The thermostats fan switches are normally set to auto. i only switched them to "on" while trying to troubleshoot the problem.

The compressor light on the board was cycling very rapidly. I'm not sure if the actual compressor was cycling at that same time as i did not have someone outside while i was in the attic. I have however been outside when it seems to be cycling frequently.

Thanks

Update from last night...

Still having some random issues with the compressor LED cycling rapidly (& randomly). All else seemed to be running OK.

I got the following readings when checking voltages while everything seemed to running OK (stayed on the transformer common while taking readings)...

Thermostat = 24V
Dampers = 24V
Transformer = 24V
Everything on the "system" terminal strip (compressor, fan) = 11V ???????? Is that right?

[Pcyrana]

You say the compressor light on the board was flashing rapidly. How rapidly would that be.
The Zone Panel that you have has a 2 minute short cycle timer built in so that it will not bring on the compressor more than once within two minutes.
Do you think that light has come on twice within a two minute period?
When you were checking voltage on the system terminal strip, what terminals are you checking across?
If you are referencing the Common or "C" terminal on the system terminal block, is there a wire connected to that C terminal from the equipment?
What voltage to you read when you measure across terminals "RC" and "C".

[bham]

well i found a wiring problem and thought i had the problem fixed. everything seemed to be working fine for the last week, but I am now having the same issues again.

The compressor light is flickering on and off within seconds; however, the compressor continues to run.

I was not checking the voltage correctly. I was using the common terminal on the transformer strip on the control board. My board does not have a common terminal on the system strip. Since there is no common terminal on the system strip i am now using the common on the air handler.

When the fan is on, the fan light on the board is on. The voltage reading fluctuates between 8-22.

The compressor light on the board is on when the compressor should be on; however the compressor is not always running when the light is on. When the compressor is on the voltage is about 25.

[Pcyrana]

You are correct that when checking voltage on the system terminal block of the zone panel you have to reference the common in the Air Handler.
The flickering Compressor light concerns me.
Can you check the voltage you have coming into the board and let me know what you have at the 24V Transformer Terminal Block?
Are you using a Supply Air Sensor with the Zone Panel? If so, is the SAS light ever lit when this problem is occurring.
If there is any way you can call me when you are troubleshooting this, that would make things a lot easier.
Thanks,

[bham]

I will try to call in the next day or two. It is difficult to time as the problem seems to be random. Do you have normal working hours?

The 24V transformer terminal block reads about 25V.

There is a supply air sensor, but i have never seen that light on.

[Pcyrana]

Our normal business hours are Monday through Friday 8am to 5pm Eastern Time.

[bham]

I'm am going to try to call you around 4 sometime this week...assuming your days aren't different being a holiday week.

I am also going to try to email you a video of the control board flickering. It seems like if I push it just right, everything will work well for a while. I have noticed that when the equipment stops working and i look at the control board, the status light is blinking and all 3 damper lights are on. However, i do not have a zone 3 and there are no wires on that terminal (do not know if that means anything).

Does the compressor LED come on when the thermostat calls for the compressor to turn on or does it come on only when the compressor is actually running?

Thanks for your help.

[Pcyrana]

When the light is on, the contacts on the system terminal block are closed and the compressor should be energized.