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Comfort Specialist
Comfort Specialist, HVAC Technician
Category: HVAC
Satisfied Customers: 1368
Experience:  Master Lic. holder for HVAC & Gas, Contractor, Estimator, Designer, Air Balance Certified, LG Master Commissioner, UNC Cert. holder for Industrial Ventilation
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I just bought a Honeywell RTH2310 programmable thermostat which

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I just bought a Honeywell RTH2310 programmable thermostat which replaced the RTH 230B. As i did not use all the wires for the latter thermostat, is the same true for this replacement? I have a carrier a/c unit.
Hello. My name is XXXXX XXXXX I'll do my best to help. Troubleshooting often requires meters and test equipment. Let's get started and see what we can do.
If you can tell me what wires you have to each terminal currently and what type system you have, we will go from here.
Customer: replied 3 years ago.

The ac system is Carrier...The wires are color codes, as you know. The connections are marked by the letter of the color. There is a jumper at the R .


OK, by type of system I was not asking Brand?
I meant is it a gas, or electric? Heat pump or non heat pump?
Since this thermostat will not work on heat pump we basically have two choices. Gas or Electric.
First if verify the little jumper on back is set correctly.If you have gas heat it should have come set HG.If you have electric change jumper to HE.
Wiring should be Red to RC and RH (This is 24v power)
White to W (This is to control HEAT)
Yellow to Y (THis controls outdoor in Cool mode)
Green is G (Controls blower). Let me know if all is correct and we will go from here.
Customer: replied 3 years ago.

electric system..the jumper is placed in r/rc

OK did you set the little jumper on back of thermostat to HE? It comes form factory set at HG and must be changed This is not where your controls wirs are connected.It is a seperate jumper.Plastic that clips on prongs



Customer: replied 3 years ago.

It is set to electric...I moved it from the factory setting.

Ok, now lets try each mode. Will fan come on in FAM mode? Will heat and cool come on in their modes? If not we will try a couple of troubleshooting steps to determine if issue is in thermostat or unit.
If nothing will come on. there are a few things we can check.
Remove wires from thermostat.Touch R to G and blower should come on. Touch R to W and heat should come on.Touch R to Y and outdoor unit should come on.If nothing comes on, your problem is not in the thermostat.So you can reconnect all wires.
If unit was working before replacing thermostat, it is possible you let two wires touch somewhere while replacing , that shorted either a small fuse in the air handler or shorted the transformer.
You stated that all of the wires were not used. You may have a blue (Common ) wire from unit that is not used.If it by any chance touched the red wire ,they would short out and blow either fuse or transformer if you did not turn power off at indoor unit before starting.
Let me know and we will go from here. Also if you have a volt meter so we can check voltage at different locations will be helpful.
Customer: replied 3 years ago.

I checked the 3 amp fuse on the unit to see if it was wasn't but I replaced it anyway..Again, the heat will come on....just can't seem to get the ac to come on

Customer: replied 3 years ago.

I turned the power off at the breaker before I began anything.


Customer: replied 3 years ago.

I touched the red to yellow and the outdoor unit what does that mean?

Customer: replied 3 years ago.

OKAY: R to G works..blower comes on...R to W works and heat comes on...R to Y works as outdoor unit comes on..Do you think I need to remove the jumper from R/RC?

Customer: replied 3 years ago.

and where would the transformer be located?

Customer: replied 3 years ago.
Relist: Incomplete answer.
I have been waiting over an hour for a response after I have continually added information from suggestions he made.

Hello there! I'm Norman but you can call me Norm. I'm sorry the other experts have stepped away.

Let me see what I might can do to help.


First so I understand the exact setup you have tell me what color wires you have going to which terminals on the thermostat. LIke Orange to O/B, White to AUX, etc.


From what I read you seem to have voltage as required and it sounds like the system is operating when jumped. My thoughts are it is a simple, but very common, thermostat setup issue.


I'll be standing by for your reply.

Also, please tell me what color wires connected to what terminals on your old thermostat.
Customer: replied 3 years ago.

Okay....maybe it's not fixed


I'm here to help if you still need it.


I'd also like to know with your system did the outdoor unit run when you would heat the home before and cool the home or did the outdoor only run for A/C mode and rely on the indoor furnace for heating?

Customer: replied 3 years ago.

Okay....The wires are: Left to right...brown...not connected: green, yellow, white, red into the rc slot...and jumper from r/rc removed.


When I tried the r+g wire, the blower came on...r+w wire, the heat came on...r+yellow, the outdoor unit came on.

Ok, the R to Rc jumper HAS to be in place. If not you will find that you can cool but not heat.
Customer: replied 3 years ago.

okay..putting that back in place now

Am I to understand that you heat solely with a fully electric furnace? No gas?
Customer: replied 3 years ago.

ac is electric : heat is on the same unit...the only gas is the water heater

So the outdoor unit never runs when the system used to heat?

Customer: replied 3 years ago. does...I can get the heat to come on, but not the ac since I changed out the thermostat

I need to understand more about your system.


Does your system have two components, an indoor air handler and an outdoor condensing unit or is this an all in one unit (packaged) with the only equipment outdoors?


Customer: replied 3 years ago.

I live in a condo....there is a component outside and an indoor component, air handler.

So back when everything worked great it relied on the outdoor unit to run for both cooling and heating?
Customer: replied 3 years ago.


That's what I was thinking but when you tell me you used the RTH230B thermostat before that's where I'm getting thrown off. This thermostat as well as the RTH230B are both for conventional heating/cooling systems. If your outdoor unit is supposed to run in both heating and cooling that would mean you have a heat pump and neither the old RTH230B nor this thermostat are made for a heat pump application.


With a heat pump the outdoor unit runs for both heating and cooling and it changes state based on 24v applied via the reversing valve wire O/B.


With the RTH230B Did it work for both heating and cooling and operate just fine in both modes? Also, did you ever have an orange wire that was being used?

Customer: replied 3 years ago.

The 230 worked for both...the orange wire was taped off.


And you had the 230 wired just like this one?
Do you happen to have the model number for the outdoor unit?
Customer: replied 3 years ago.

carrier model 38cks split a/c system

Ok, that model number is XXXXX A/C unit only. That tells me a lot.


So with all 4 wires connected and a jumper from RC to R what happens when you try to use the thermostat to run the system? This knowing that jumping the wires together allows the system to function as it should.

Customer: replied 3 years ago.

There are 5 wires connected. Are you saying that the orange one shouldn't be?Orange, green, yellow, white and red are connected. The brown wire is taped off, not connected....

Red should be to Rh with a jumper to Rc

White should be to W

Green to G

Yellow to Y


The rest capped off.

Now what happens when you try to use the thermostat. Please consider there may be a time delay between when you turn it on and when the system starts and also between heating/cooling modes.


Could take as long as 5 minutes.

Customer: replied 3 years ago.

waiting now

Customer: replied 3 years ago.

While I am waiting, let me take the opportunity to thank you for your help. I am technologically savvy in my job, but when it comes to homeowner stuff, I am sadly lacking, but willing to learn.

Not a problem. We're here to help as we can. Some of us have to come and go based on our schedule. I'm just hoping we can get you up and going and solve this issue.
Customer: replied 3 years ago.

If it doesn't happen to work, what thermostat do you recommend that I can go get on a Sunday?

There's nothing wrong with this model thermostat. If the jumping you did works but the thermostat doesn't then the problem is clearly the thermostat.


Any Honeywell would be fine. We use a lot of Focus Pro's which seem to work great. Be sure to go with the programmable again.

Customer: replied 3 years ago.

Okay...I think it has been 5 minutes and it has not kicked on, so I am going to return this and get another....

Yeah. I feel confident with what you've told me that the thermostat is the culprit. Your system is a 1 stage heat / 1 stage cool thermostat so make sure you buy one that works for that application. Most any thermostat will but in Lowes or Home Depot you may find lots of thermostats with bells and whistles so have fun with that.


If you find that you have more questions simply reply. Good working with you!

Comfort Specialist, HVAC Technician
Category: HVAC
Satisfied Customers: 1368
Experience: Master Lic. holder for HVAC & Gas, Contractor, Estimator, Designer, Air Balance Certified, LG Master Commissioner, UNC Cert. holder for Industrial Ventilation
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