comfortnet issue

[RBrudi]

First of all, I work for a distributor and am trying to help one of my customers, any response is appreciated.

Communicating Equipment:

DSZC160601 HP
MBVC2000 AHU
CTK04 Tstat


My customer is having some communication issues between the t'stat, blower, and heat pump. The thermostat is calling for heat, the condenser starts up, the blower starts up, the condenser cuts out, the blower continues to run, the thermostat then says "updating equipment". 15 minutes later the condenser starts back up and the cycle continues.

There are no error codes displayed on the heat pump. All of the boards on the blower and heat pump have been replaced, the thermostat has also been replaced.

When the system is running, pressures are normal and nothing "seems" to be mechanically wrong.

I am out of suggestions and my knowledge on these comfortnet systems is limited.

Does anyone have any suggestions? Thanks!

[HVAC_Kyle]

We have had so many problems with that same equipment, (2 stage 16 seer heat pump) we had to stop selling goodman products all together. Is the system wired as communicating or non-communicating?
Is the programming/wiring correct? I would start there. I have found that those systems are very temperamental with static air pressure. If they are being installed in existing ducting (retro fit), you will need to make sure it does not exceed .5 total static pressure across the blower, or it will most likely shut the heat pump off due to high head pressure. That will throw a fault code at the outdoor unit for high pressure lock out. Communicating wiring is also NOT supposed to have any splices in the thermostat wiring, or it can cause communication errors, as I believe the communicating wires are DC voltage opposed to AC voltage, so the signal on DC is flowing through the core of the wire and not the outside like AC, or typical non communicating systems.

[RBrudi]

We have had so many problems with that same equipment, (2 stage 16 seer heat pump) we had to stop selling goodman products all together. Is the system wired as communicating or non-communicating?
Is the programming/wiring correct? I would start there. I have found that those systems are very temperamental with static air pressure. If they are being installed in existing ducting (retro fit), you will need to make sure it does not exceed .5 total static pressure across the blower, or it will most likely shut the heat pump off due to high head pressure. That will throw a fault code at the outdoor unit for high pressure lock out. Communicating wiring is also NOT supposed to have any splices in the thermostat wiring, or it can cause communication errors, as I believe the communicating wires are DC voltage opposed to AC voltage, so the signal on DC is flowing through the core of the wire and not the outside like AC, or typical non communicating systems.

I will mention the static pressure to him. There are no splices in the wire, but it is 18ga solid tstat wire. Do you know if there is a different specification on the wire?

[HVAC_Kyle]

18ga should be fine, Who said to change out all the control boards? was this tech support? I would have the installer look over the installation instructions 1 more time, just to make sure all the wiring is correct before changing more parts. Was this a retro job or new construction?

[RBrudi]

18ga should be fine, Who said to change out all the control boards? was this tech support? I would have the installer look over the installation instructions 1 more time, just to make sure all the wiring is correct before changing more parts. Was this a retro job or new construction?

Retro. Yeah this was Goodman tech support, I have to warranty all of the stuff...

[HVAC_Kyle]

are you sure the thermostat says updating equipment and not waiting on equipment?

[captube]

Have him check the Bias dip switch settings on the boards. I believe there is a .6 volt difference for proper comm. Ck. with tech support or read up on checking it. Incorrect it will give erratic operation .

[HVAC_Kyle]

If it is wired for communicating, you do NOT use the dip switches, all programming is done at the thermostat, including airflow trim

[HVAC_Kyle]

This communicating system will bypass the dip switch settings at the control board when wired and programmed for true communicating with a CTK03 or CTK04 thermostat

[captube]

You will be changing the bias switch setting if not correct on comm. systems. Bias is for the network and may or may not be correct refer to network trobleshooting.

[HVAC_Kyle]

Got it. BIAS AND TERM DIP SWITCHES MUST BE IN "ON" POSITION. RED
STATUS LED PROVIDES NETWORK STATUS. GREEN RX LED INDICATES
NETWORK TRAFFIC. USE LEARN BUTTON TO RESET NETWORK.

[captube]

Also if you dont have .6 v. differential with them on turn both boards to off and recheck.

[hvacvegas]

Sounds like someone didn't install the transformer on the outdoor unit.

[RBrudi]

The new board that took place of the original board required a ground, where the original didn't. This fixed the problem. Maybe I wasn't looking hard enough, but I could've sworn I didn't see anything mentioned about a common wire being needed. Makes sense though, as the system was operating but was operating erraticly.

[bw44586]

I have a solution for this issue.

google the following: Data Line Voltage Troubleshooting and Bias Switches