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50+ Years of Serving
The Shreveport Area

50+ Years of Serving The Shreveport Area


Moon's Air Blog

Why Won’t My Heat Pump Change to Heating Mode?


Heat pumps offer many great advantages to homeowners. But the best one, the one that made most people want to get a heat pump installed in the first place, is that heat pumps can work as both air conditioning and heating systems. All it takes to change a heat pump from one mode to the other is a thermostat adjustment. 

Except when, for some reason, a heat pump doesn’t change mode. Heat pumps can run afoul of malfunctions, just like any other piece of HVAC equipment, and if your heat pump is trapped in cooling mode or it’s only sending out room temperature air, you’ll wonder if you need to call the Moon’s Air team for heating repair in Haughton, LA

We’ll take a look at why you may have a heat pump in this predicament. 

Broken Reversing Valve

If your heat pump will only work in cooling mode or “fan-only” mode, a likely source of the problem is a failed reversing valve in the outdoor unit. This valve is a critical component that makes a heat pump work differently than a standard AC. As refrigerant exits the compressor, the reversing valve determines which direction it will move. The direction determines what mode the heat pump will work. The valve can become stuck, and when that occurs, the heat pump will remain in one mode—usually cooling mode, which is the “default” setting for most reversing valves. 

The best way to solve a broken reversing valve is to call our technicians. We can replace the valve with a new one and get the heat pump back to doing both halves of its job.

Failed Thermostat Connection

The reversing valve may be fine—it’s just that the thermostat isn’t able to signal it to change modes. A thermostat has multiple connections to the HVAC system, so it may still be able to control other parts of the heat pump (such as turning on the compressor and blower motor) but not be able to send the electrical current that charges the reversing valve so it switches modes. Our technicians will always check the thermostat to see if it’s the cause of the problem.

Miscalibrated Thermostat

Here’s another potential thermostat issue: the thermostat is properly connected to the heat pump’s reversing valve, but it’s sensing incorrect indoor temperatures and therefore doesn’t register that it needs to switch the unit over to heating. You can try raising the thermostat setting up high to see if this causes the heat pump to kick into heating mode. However, don’t keep doing this! This is just to check on the problem. You’ll still want professionals to recalibrate the thermostat so it works correctly.


We’ve listed the most common causes of a stuck heat pump, but there are various other malfunctions that can cause a heat pump to lose its heating capacity (and also affect cooling capacity). These include a drop in airflow, duct leakage, loss of refrigerant, and dirty refrigerant coils. Leave the diagnosis of the problem to our experts and we’ll see you have your heat pump working great once more. 

Moon’s Air has provided whole-home comfort since 1971. Call us for service today—it’s good to be Mooned!

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