# Question about Control Board Code - 2 stage AC



## IonC (Jul 24, 2016)

Hey all, I had a new unit put in this past fall, it is a Goodman 2 Stage Heat/Cool with a Variable speed blower and 5-ton compressor. It performed really well this past winter and has done OK up until this big heat wave we have right now. It is keeping the house pretty cool but I am worried it is not running at full capacity (2nd stage). I did some research (read the installation manual) and found that several dip switches were not set to match the 5-Ton unit outside. I believe I have those correct now according to the Installation Manual.

Also, I have a Honeywell thermostat that when viewing the Equipment Status it says that both stages of cooling are ON. This is good right but my main question is, the code on the control board on the unit is flashing "P1" then "12" and alternates. If I am understanding the Goodman literature correctly, this means that it is running at 1200 CFM and Low Stage Gas Heat (obviously it is not because it is cooling). Shouldn't I be seeing a code like C2 then 19 (1900CFM) on Stage 2 cool? Could there be something mis-wired? The codes on the board are what have me worried. 

The model # of my furnace/blower is GMVC81005CX, the compressor is DSXC160601.

Thanks for any input you might have.


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## Bob Sanders (Nov 10, 2013)

I have that Goodman in the 4 ton version (DSZC160481 with the AVPTC48D14 variable speed air handler) and you most likely have something connected wrong.

For cooling you SHOULD be seeing C1 for low stage and C2 for high stage.

P1/P2 are stages in heat pump mode.

Your gas heat (or axillary heat) should be H1/H2

Is your reversing valve wire connected to the air handler/gas furnace?


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## IonC (Jul 24, 2016)

Bob Sanders said:


> I have that Goodman in the 4 ton version (DSZC160481 with the AVPTC48D14 variable speed air handler) and you most likely have something connected wrong.
> 
> For cooling you SHOULD be seeing C1 for low stage and C2 for high stage.
> 
> ...


Well this made me ponder that the people who installed this may have not been the most competent in the world so I am going to try to make myself competent to this system. So I checked the Thermostat wiring and NOTHING was hooked to Y2. I have to assume this is a problem. LOL My thermostat wire has several extra wires so I am going to hook up a wire to the second stage and see if I can get the 2nd stage going properly. Then I will check all the other wiring.

As far as the Reversing valve wire, I am going to have to see what they have going on.


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## Bob Sanders (Nov 10, 2013)

The HP doesn't necessarily need to be connected at the thermostat for Y2 to work. It depends on whether or not it was jumpered at the condenser or furnace. If you have a dual stage thermostat though (and it sounds like you do) then you would benefit from its connection. my pure guess is that they took some shortcuts because they didn't have enough wires running to your thermostat. That's what it normally is anyway.

If the reversing valve wire is not connected to the furnace then the furnace controller will not know which mode the HP is in since it gets that info from this wire (it will default indicate heating mode P1/P2). The system will however work normally if the wire is not connected.


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## IonC (Jul 24, 2016)

Bob Sanders said:


> The HP doesn't necessarily need to be connected at the thermostat for Y2 to work. It depends on whether or not it was jumpered at the condenser or furnace. If you have a dual stage thermostat though (and it sounds like you do) then you would benefit from its connection. my pure guess is that they took some shortcuts because they didn't have enough wires running to your thermostat. That's what it normally is anyway.
> 
> If the reversing valve wire is not connected to the furnace then the furnace controller will not know which mode the HP is in since it gets that info from this wire (it will default indicate heating mode P1/P2). The system will however work normally if the wire is not connected.


I have the Honeywell Wifi Smart Thermostat. It has a W/O/B connection and it is connected with a white wire to W1 on the furnace. Nothing connected to O on the furnace. There are 2 extra wires now that I hooked one to Y2 on both sides. (Thermostat and Furnace). Still blinking P1 12. So if I jump O on the furnace side to W1, will that fix it?

When you say HP you mean Heat pump right? My furnace is gas fired, so no heatpump. Thermostat is not set to heat pump so I am a little confused how the control board even thinks a HP is involved? Sorry if that is noob logic?


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## IonC (Jul 24, 2016)

Bob, I was able to clear the "P" issue by putting a jumper between Y1 and O. I also made sure that Y2 was wired all the way through to the condenser. So now I am testing to see if I can get the 2nd stage to kick in properly. It is running at C1 12 now, thermostat says Stage 2 is ON but I am not seeing a C2.


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## Bob Sanders (Nov 10, 2013)

Sorry... thought it was a heat pump. But yes... O needs power for the control board to register the C1, C2 properly. A jumper wire works, but I am surprised there is no jumper switch on your furnace for that purpose. Either way works though.


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## IonC (Jul 24, 2016)

Bob Sanders said:


> Sorry... thought it was a heat pump. But yes... O needs power for the control board to register the C1, C2 properly. A jumper wire works, but I am surprised there is no jumper switch on your furnace for that purpose. Either way works though.


Yeah thanks, I am more upset that the idiots who did the install didn't have that done already. I think they did manage to jump the condenser 2nd stage at the furnace but I prefer it run to the thermostat. Do you know of anything with these furnaces that will prevent C2 from kicking in during regular operation? Does the temperature in the house have to be at a certain point before C2 will even kick in?


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## Bob Sanders (Nov 10, 2013)

IonC said:


> Yeah thanks, I am more upset that the idiots who did the install didn't have that done already. I think they did manage to jump the condenser 2nd stage at the furnace but I prefer it run to the thermostat. Do you know of anything with these furnaces that will prevent C2 from kicking in during regular operation? Does the temperature in the house have to be at a certain point before C2 will even kick in?


If Y1 and Y2 are jumpered at the furnace then low stage is being bypassed and you go directly into 2nd stage on cooling demand.


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## IonC (Jul 24, 2016)

Bob Sanders said:


> If Y1 and Y2 are jumpered at the furnace then low stage is being bypassed and you go directly into 2nd stage on cooling demand.


Yeah no jumpers there, just can't seem to get the 2nd stage to kick in. Runs at C1 12. I figure that is perfect for the 1st stage but just wondering why I am not seeing C2 18 or 19! I gotta get this thing cranking, it's hot. :devil3: LOL


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## beenthere (Oct 11, 2008)

Check the jumpers on the furnace control board. May need to set a jumper to tell the furnace that it has a 2 stage A/C connected to it.


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## Done That (Apr 28, 2011)

You have a 2-stage furnace and a 2-stage AC only outdoor unit. So the only terminals that need to be wired for correct operation are R,C,G,W1,W2,Y1,Y2.

If you posted pics of the wiring at the thermostat, furnace board, and outdoor board we could probably straighten this out.


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## sidejobjoe (May 30, 2014)

Just to start with the basics again (which you may have checked already) but...

Even though your T-Stat is saying 2nd stage, do you have 24VAC between C and Y2 at the T-Stat when it says this? Do you have 24 VAC between C and Y2 at the furnace control board?

If your unit is like mine (Goodman 5ton 2stage in upflow config), I had some trouble wiring mine up at the furnace board because it is so close to the ground - it is hard to see what screw terminals go with which T-Stat wire. I put wires in the wrong screw down blocks initially. 

Also check that Y1 and Y2 are energized at the T-Stat (when calling for stage 2). 


And, as suggested by BT, checking the jumper config is real good idea also


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## Done That (Apr 28, 2011)

There is no dipswitch setup required on the furnace board to let it know it is connected to a 2-stage outdoor unit, only the connection of Y2.


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## sidejobjoe (May 30, 2014)

Just for fun, jumper C to Y2 at the furnace board... it should now display C2 (and if you currently are set to 1200 CFM; "12" on low, it should now say C2 "19"). 

Do note there are a variety of "ramp" profiles you can set via jumper config for the blower speed, so it may take 10 minutes for it to get to the "19" speed.


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## IonC (Jul 24, 2016)

Done That said:


> You have a 2-stage furnace and a 2-stage AC only outdoor unit. So the only terminals that need to be wired for correct operation are R,C,G,W1,W2,Y1,Y2.
> 
> If you posted pics of the wiring at the thermostat, furnace board, and outdoor board we could probably straighten this out.


I can do that but the wires are pretty basic, at least to me. I wired in an Aprilaire 800 to the G so the Aprilaire would kick on the blower if it needed to in the Winter. That's really the only unusual wiring (except that there was no Y2 wired to the Stat). The guy that did the install used the Black thermostat wire at the condenser to Y2 out there and I used an extra Orange to connect Y2 at the Stat. It bothers my OCD that those two wires are different color but it should work fine. 

I will check the voltage down at the furnace to make sure Y2 has 24V when it says it is on. If it does I will check at the condenser as well.


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## Done That (Apr 28, 2011)

I agree, the wiring _should _be pretty basic, but apparently somewhere along the way it may have been messed up. 

That said, it's one of the more complex control setups in the Goodman lineup. Controls had to have been properly programmed with correct system data sets at the factory, and no one should have overridden that by placing new eeprom cards onto the controls, etc etc. Just lots of opportunities for things to go off course is all. Hope you get it all sorted.


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## IonC (Jul 24, 2016)

Done That said:


> I agree, the wiring _should _be pretty basic, but apparently somewhere along the way it may have been messed up.
> 
> That said, it's one of the more complex control setups in the Goodman lineup. Controls had to have been properly programmed with correct system data sets at the factory, and no one should have overridden that by placing new eeprom cards onto the controls, etc etc. Just lots of opportunities for things to go off course is all. Hope you get it all sorted.


Thanks, I will try to post some photo's tonight. It never hurts to have another set (or a few) of eyes on it. I thank everyone for their/response time so far.


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## IonC (Jul 24, 2016)

sidejobjoe said:


> Just for fun, jumper C to Y2 at the furnace board... it should now display C2 (and if you currently are set to 1200 CFM; "12" on low, it should now say C2 "19").
> 
> Do note there are a variety of "ramp" profiles you can set via jumper config for the blower speed, so it may take 10 minutes for it to get to the "19" speed.


I was about to post a bunch of photos and your post made me think, get back to basics. Y2 must have power from the stat. Stage two on, no power to the orange wire. Well me being the idiot I am didn't think that the dopey hee-haw installers didn't patch all the wires through on their extension cable. Needless to say, this is fixed. I tested by putting a jumper from Y1 to Y2 to give Y2 power, C2 fired right up without issue at 1900 CFM. Then started testing the orange wire and nada. Traced it back to the jumper and there hang 3 wires unmatched to their jumper stat wire. Also figured out that W2 was not connected to the thermostat....WTH? Glad it was a mild winter that's probably why I didn't notice.

I noticed that when the Fan turns on full speed at 2000 CFM that it slows down a little and flashes the B3 code. I am guessing there is an airflow problem possibly but I did have the cover off the unit so I will put it back together before panicking on that.

Thanks for all the help troubleshooting this. Happy in HOT Virginia...


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## IonC (Jul 24, 2016)

Done That said:


> I agree, the wiring _should _be pretty basic, but apparently somewhere along the way it may have been messed up.
> 
> That said, it's one of the more complex control setups in the Goodman lineup. Controls had to have been properly programmed with correct system data sets at the factory, and no one should have overridden that by placing new eeprom cards onto the controls, etc etc. Just lots of opportunities for things to go off course is all. Hope you get it all sorted.


You were 100% correct. Wiring issue... thank you for all your input. Would you mind taking a look at my dip switches to see how they look. I'd just like a double check. I am attaching a photo.


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## IonC (Jul 24, 2016)

OK, so now that I have stage 2 running another issue. Code B3. I have an Aprilaire 2410 Media Filter and as soon as I remove the filter, C2-19. Obviously the 2410 is restricting airflow. I have returns Upstairs, Mid level, and in basement. I do have registers closed to a couple non-used rooms. Seems to me the problem is the filter OR I need to cut back the fan trim. Thoughts? 

My house unfortunately wasn't built with a dual zoned system. I hate it but it is what it is...


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## sidejobjoe (May 30, 2014)

Is there a schematic on the inside of the panel you took off? Sometimes they put the error codes there for you.... but I looked it up anyways  (this may help you. install instructions for the same or similar unit you have http://www.alpinehomeair.com/_viewresource.cfm?ID=2252) 

B3 means the ECM motor is throttling down due to reaching a power, speed or temp limit. There is a good chance this means the static pressure of your ductwork is too high. You can test that with a digital manometer....they are fairly cheap to buy. 

Does it go code B3 when the lower (blower chamber) door is off or just when it is all sealed back up (if so, probably static pressure problem) ? 


ECM's are nice because they will work as hard as they can to put out the requested CFM. That also means if the static pressure of the system is too high, they will use too much current and cycle down to protect themselves. 


Sounds like you had some real chuckleheads put that system in. Sad so many hack-job techs give good techs a bad name.


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## sidejobjoe (May 30, 2014)

Also, wanted to say, open up all those vents ... that increases static pressure.... and you will have to figure out something with the filter.


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## IonC (Jul 24, 2016)

sidejobjoe said:


> Is there a schematic on the inside of the panel you took off? Sometimes they put the error codes there for you.... but I looked it up anyways  (this may help you. install instructions for the same or similar unit you have http://www.alpinehomeair.com/_viewresource.cfm?ID=2252)
> 
> Does it go code B3 when the lower (blower chamber) door is off or just when it is all sealed back up (if so, probably static pressure problem) ?
> 
> Sounds like you had some real chuckleheads put that system in. Sad so many hack-job techs give good techs a bad name.


Well when the door was off the Fan ran at 100% (i had it ON for testing) and it cycled up to 2000cfm or 20 on the LED. Then went down to 18 before the b3 message appeared. When I put the door on, C1 runs to 12 without issue with media filter in. When C2 engages it spins up to 1900CFM or 19 then down to 18, then b3...If I remove Media filter, C2 19 appears almost immediately. 

I was thinking (and this could be dumb) what if I poke a few holes in the media filter to increase the flow? it will still filter a lot. It's the Aprilaire 413 (Merv 13). Might just be overkill and limiting?


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## sidejobjoe (May 30, 2014)

I wouldn't put holes in the filter. You will then introduce other problems like a dirty evap coil (BTW, may be worth check that....though unlikely it is very dirty with *that* filter on it  ). 

I would try to find a less constricting filter (I presume these exist??) .... but I would also check the static pressure of your ductwork. Right now you system is telling you something, namely the static pressure is high... running an ECM in a high static pressure system is a sure path to premature ECM death (which are *very* expensive to replace). 

Also, opening up all the ducts in your house may help quite a bit. 

I went with with an electronic air filter for my house because the ductwork is undersized and my static pressure if border line *with* it (something .7" w.c. @ 1900 CFM). 

As a stop gap, you could throttle down the speed of the motor either via the "trim" adjust or overall.... i.e. on switch bank S3 flip all 4 switches to ON (you only have one off now) and that will trim it down -10%. You can then go to the speed "C" setting if that doesn't work. You can find these setting on page 40-41 of that link I included of the manual. 

Even if that works, I would recommend dealing with the filter constriction sooner rather than later... if you tweak down the CFM, your ECM is still going to be running close to its limits.... which is not good for the longevity of the motor. 

Good news is, hopefully your system will be running on C1 most of the time limiting the ECM from working so hard .


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## beenthere (Oct 11, 2008)

Get a MERV 8 filter. Don't put holes in the MERV 13. You would have more holes in it then you think to get B3 error code to stop coming up.


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## IonC (Jul 24, 2016)

beenthere said:


> Get a MERV 8 filter. Don't put holes in the MERV 13. You would have more holes in it then you think to get B3 error code to stop coming up.


I think they only make a 10 for Aprilaire 2410.


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## beenthere (Oct 11, 2008)

IonC said:


> I think they only make a 10 for Aprilaire 2410.


That will probably be a lot less restrictive then the 13.


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## IonC (Jul 24, 2016)

OK, so I got the 410 Filter from Amazon Prime and so far so good. No more B3 error at +5% trim. Went through all the dip switch settings and it finally held steady without error at C2 18 with the Merv 10/11 filter. I guess I'll have to live with it. A couple hundred CFM under what the blower is capable of design wise but it should do the job. 

Thanks to everyone who helped me out. I learned a lot and have a good basic knowledge of the system which is probably a lot more than most can say about the units cooling/heating their homes. 

-kevin


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