Odd fan/compressor sequence?
Carrier 5T Heatpump system with a Focus Pro 5000 thermostat.
While the AC was operating, I raised the temperature 2 degrees. A few minutes the AH fan shut down (after the normal delay), but the compressor kept running, would not turn off even if I took the T-stat out of cool mode. I pulled the outside breaker, turning off the compressor. Now the system works normally: temperature reached, compressor shuts down, a few minutes later the AH fan shuts off.
What could have caused the compressor to keep going with the AH fan off?
Could changing the temperature setting on the T-stat have temporarily scrambled something in the T-stat that could have caused this.
But I thought the AH fan was turned on and off from a contactor at the condensor that also controls the compressor/fan contactor preventing the compressor from operating without sending power to the AH.
What would have happened if this had happened if I did not pull the breaker?
Thanks for help.
The OD unit doesn't any control over the indoor unit unless its 2 stage.
Your stat may be wired or configured wrong.
If its a new install, call your contractor back.
It's not a new install. The system has been working fine this winter in HP mode and this summer in cool. The manual fan control works too.
It seemed like the stat hung up. Has that happened with this type if the temperature is changed too quickly under certain circumstances?
The system operating normally now. I am not sure I could duplicate what happened but something did.
When would the condensor have kicked off and what condition would have caused it? I suppose that the coil would have frosted up, but without air running over it not much ice would have accumulated before the condensor shut itself off.
Hard to say for certain what exactly caused your problem. It's possible the triac or relay inside the thermostat that energizes/de-energizes the compressor contactor got stuck on. Also possible the compressor contactor itself got stuck on. When you hit the breaker, the contacts cooled enough to let go...possibly. If the system has a few years on it and you've never had the outdoor compressor contactor replaced, might be a good idea to get that done. Being it's a heat pump, the compressor runs year round, so contactor life is used up more quickly than for straight a/c.
New contactor and fan on the condensing unit in January.
As said before, what would have happened if I was not around, although I suppose if I wasn't the temperature setting would not have been manually raised is some way that caused the odd operation.
I thought that as long as the compressor contactor was closed, the AH fan would run. It's a SP fan, but runs for about two minutes after the compressor stops. I thought the control for that was in the condensor.
give the service guy a call, your outdoor equipment needs attention. The stat is not going to keep the condenser on without the air handler on.
Originally Posted by Carry On
You can't fix stupid