Air conditioning running when heating

While working on the basement today, I noticed that even though the gas furnace was heating, the airconditioning was running as well. Don't know for how long but there was quite a bit of ice build up on the compressor in the bottom of the outside unit.

The heat just started coming on over the past weeks so I wouldn' t have noticed this earlier. Any thoughts on what the troubleshooting steps would be?

I have 2 virtually identical AC/furnace systems. THe second floor seems to be working correctly. The first floor is the problem child.

I have Honeywell Lyric thermostats on both. I checked the thermostat configuration of the problem unit and it seems to be ok.

 

Is the thermostat programmed as a gas furnace with A/C ?
It may be programmed for heat pump operation which would explain what's happening.

 

After some troubleshooting, the wiring on the two was different and it looks like the compressor was probably running full time regardless of demand probably for the last few months. I had some issues late spring and must have installed the wires wrong (bone head). I fixed the wiring but should I be worried about any damage? Anything I can check? I am guessing that compressor damage could be a serious possibility. The AC was working in the past couple of weeks. Appreciate any comments.

 

If it was icing up then it was still working ok. It's water over the dam now.
I wouldn't worry about it too much.

 

PJ max
Although the furnace is now working without the A/C compressor turning on still not out of the woods.

Today I had an opportuniuty to check the system out on the AC side. It will not come on.

When the thermostat is demanding, the contactor is not closing.

Things I have checked
1. I have power on both leads to the contactor.
2. If I remove power to the compressor, I can use 24V to close and open the contactor.
3. ON the AC/Furnace combo that works (2nd floor), the control wires to the AC unit are on Com and Y terminals. When there is demand, the Y to Com gives +24V AC. When it isn't, I get 0 V AC
4. On the unit that doesn'twork (first floor), Y to Com gives 0 Volts regardless of if the thermostat is demanding.

Bad Thermostat? THe thermostat is working fine for heating.

 

Ok
FInally figured everything out.I am using a Lyric ROund thermostat. Once I got to the " NO output on the Y connector" problem statement, I was able to troubleshoot the situation. At first I though that the problem was going to be in the thermostat itself figuring that was where the electronics were but the problem was actually with the wall plate. I have two identical thermostats. Swapping the known good to the problem location using the existing wall plate, the problem persisted. It was only when I swapped the wall plate that the problem was correctly. This wall plate has delicate connectors. THere is no visible damage or other issues but it was clearly the mounting plate.

Appreciate the discussion. Troubleshooting without a volt meter would have been fruitless.

 

It may be a good option to get in touch with --- with your issue.

 

The service charge for them to fly from Australia to Wisconsin might be a bit pricey.

 

You asked this specific question:

We gave you some specific suggestions as to why this may not be a good idea but you seem to not be paying attention to the details about what we are telling you.
The idea that you can overcome basic design concerns with electronic gadgetry does not address the design concerns we have expressed.


You did not offer a solution to any of these engineering problems.
The air conditioner you use does not generate heat on its own but rather moves heat that the evaporator absorbs .
Where will this heat come from when it is cool outside?

In this case you would do well to not try to re-invent the wheel and buy a unit designed for the purpose.
One possibility is that if you were considering designing a system from scratch you would need to have a competent, qualified tech to do that.
If you have someone like this you may be able to find a used system that the tech could repair/rebuild that has already been designed.