I live in North Carolina. Temperatures have been 30s during the day and teens at night. This issue has happened once before in December. Can't remember what the temperature was that day/night.

The thermostat says Heat is on, today it was set to 68 but actual temperature was 61. I felt the registers and the air coming out was cold. Probably around 60. I turned off the thermostat because I knew something was wrong. Even after waiting for five minutes the evaporator fan kept blowing cold air through the register. I pulled the thermostat off the wall thinking that was the issue but the fan continued to run. I went outside to the unit and felt the exhaust fan blowing (I don't know if that's the right name for it or not, but it's the fan that blows the exhaust of the combusted gas out of the unit). That fan was still blowing and the air was cold. So then I pulled the cut off switch and waited a minute and a half. While waiting I used my multimeter and found no short between the R wire and the W or G wires. After plugging the cut off switch back in the unit was silent. I went back inside and put the thermostat back on. Waited, nothing happened. Then I turned the heat on. I heard the exhaust fan start up. Then I heard the gas flow start and catch on (sounded like the gas water heater when it starts on). Then the evaporator fan started and I felt warm air through the register. It has been working fine since then. It has happened twice this season.

I have a 4 ton packaged heat pump/gas furnace unit. Heat pump for cool only and gas for heat.
It's a Bryant 582AJW installed in 1999.
I don't think the thermostat is the issue as it kept running and blowing cold air even when I pulled the thermostat off the wall. There wasn't a short in the wires. What would cause this issue and is it something serious that needs to be fixed or is it more of a nuisance, annoying but nothing to worry about. Ideally I'd like it not to happen at all. If it had happened at night with it being 16F outside it would have gotten really cold really fast inside.

EDIT:
Product information for my unit:
http://www.xpedio.carrier.com/idc/gr...s582a.18.2.pdf

 

That's not a heat pump. Just a packaged air conditioner with gas furnace.

The blower you are talking about is the draft inducer blower. It moves the exhaust gases thru the heat exchanger.

You need to locate the control board. It has at least one LED on it. It's job is to blink a trouble code when the furnace fails to light. The codes should be on one of the access doors for your unit and are listed below. The LED should be visible without opening a door that would turn power off as that would clear the code.

STATUS CODES: LED Explanation On (continuous) Normal Operation Off Hardware Failure:
1 Flash Modified Indoor Blower On or Off Delay.
2 Flashes Limit Switch Fault
3 Flashes Flame Sensor Fault.
4 Flashes 4 consecutive limit switches trips.
5 Flashes Ignition Lock Out.
6 Flashes Induced Draft Motor Fault.
7 Flashes Flame Roll Out Fault.
8 Flashes Internal Control Fault

 

Will that code have reset after I pulled out the cut off switch or will it still be there?

 

I don't know for sure. I can't find the full service manual for that unit. Most units will lose the code if the power is interrupted. With some units you can call up the codes after restoring power.

 

So I went out there and took off the panel to see the control board and the red light was just on, no flashes, indicating normal operation. I guess it reset after I pulled out the power cut off.

In the event that it happens again, with cold air coming from the registers, cold air coming from the draft inducer blower, and no flames visible from the grill on the outdoor unit should I take the panel off before killing the power to see the code? Or would that be unsafe? When it's working properly you can see the flames from the grill/vent on the side of the unit.

Also for peace of mind, when the flame goes out does the gas cut off automatically or does it keep flowing? Is it supposed to relight the flame if the flame goes out mid operation?

I've fixed numerous things on my own and feel competent enough to diagnose things, change relays or electrical components. However, if it deals with the actual gas components I'm not going to attempt to fix it and will just call someone to service it. The only thing is that last time they came out I got slapped with a hefty bill and they practically did nothing. They said everything looked fine. So I don't want to call them unless there's a code flashing or I know what's wrong.

Thanks for the help, PJmax!

 

Not a pro but can offer some insight.

Yes, if there is not place to view through the panel, take it off before killing power to read the code. If it was not safe to do, they would have made a view hole to read the code without removing it. They seemed most concerned about the blower area which usually has a separate panel and a safety switch.

Under normal operation, the gas is shut of when the flame goes out. It will not just keep flowing and attempt to relight. It should either lockout with an error code until reset, or it will start at the beginning and go through the entire routine for a relight.