A heat pump that heats when you want cooling, or cools when you want heat, usually has a reversing valve problem or a fault in the parts that control it. A licensed pro has to diagnose it, because the fix can mean recovering refrigerant. Climate Pros Tucson matches you with that pro.
What does a reversing valve do?
The reversing valve switches a heat pump between cooling and heating. It redirects refrigerant so the outdoor coil either releases heat (cooling) or collects it (heating). When it sticks, the system can’t change modes.
What are the signs of a failing reversing valve?
- The heat pump blows cool air in heat mode, or warm air in cool mode.
- It runs but doesn’t change mode when you change the thermostat.
- A hissing or whooshing sound from the outdoor unit that stays after the cycle changes.
- The outdoor unit ices up or steams in a way that doesn’t fit the season. See heat pump frozen or steaming.
- The unit seems to work in one mode and fail in the other.
Why do Tucson owners notice it late?
Tucson’s heating load is mild: fewer than 12 nights a year at or below 32F (1991-2020 normals at the airport). A heat pump spends most of the year cooling, so a valve stuck in the cooling position can go unnoticed until the first cold morning. Test heat mode in October, while the normal low is still 59F, rather than waiting for November, when it drops to 47.9F. See fall HVAC checklist.
What can you check first?
- Set the thermostat to heat mode and a setpoint well above the room temperature.
- Confirm the thermostat is on heat, not on emergency or off, and the batteries are fresh.
- Check the filter and make sure the outdoor unit is clear of debris.
- Wait through a full cycle. Defrost can briefly blow cool air.
If it still blows cool, stop and call a pro. Don’t open the outdoor unit or touch the refrigerant lines.
Should you repair or replace it?
Causes include a stuck or failed valve body, a bad control solenoid, a wiring fault or a refrigerant problem. A solenoid or wiring fix is a smaller job than replacing the valve itself, and replacing the valve means recovering and recharging refrigerant. Only a technician with EPA Section 608 certification may do that work.
On an older unit, a valve replacement is a good moment to compare repair vs replacement. Ask for the diagnosis, the repair option and the replacement option in writing. Related: heat pump repair in Tucson, heat pump not heating and do heat pumps work in Tucson winters. Service page: heat pump service. Area overview: Tucson HVAC hub.
When to call us
When the heat pump is stuck in the wrong mode, you need a licensed pro with the gauges and certification. Call (520) 353-2520 and we’ll match you with a licensed local pro.