In San Antonio, we don’t live in a deep-freeze climate—but we absolutely get cold fronts that make heating essential. If you rely on a heat pump and it suddenly won’t switch from cooling to heating mode, it’s more than an inconvenience. It can leave your home uncomfortable at the exact moment you need dependable warmth.

The good news: most “stuck in cooling” heat pump issues come from a handful of common causes. Some are simple (thermostat settings or wiring problems), while others require professional repair (like a reversing valve issue or refrigerant leak). Either way, the sooner you address it, the more likely you are to avoid bigger damage and higher repair costs.

If you need heat pump repair in San Antonio, TX, Cowboys Air Conditioning & Heating can diagnose the issue quickly. We serve homeowners across San Antonio, including Stone Oak, Alamo Heights, Castle Hills, Shavano Park, Leon Valley, Terrell Hills, and Downtown, with 24/7 service available. Call (210) 495-7771 to schedule heat pump service.

First: what does it mean when a heat pump won’t switch to heat?

Heat pumps don’t “create” heat the same way a furnace does. Instead, they move heat—pulling warmth from outdoor air and transferring it inside. To switch between cooling and heating, the system relies on a component called the reversing valve, which changes the direction of refrigerant flow.

When your heat pump won’t go into heating mode, you might experience:

• The system runs, but blows cool or lukewarm air

• Your thermostat says “heat,” but the house doesn’t warm up

• The outdoor unit runs strangely or the system cycles oddly

• The home never reaches the set temperature

Now let’s look at the most common reasons this happens in San Antonio homes.

1) Thermostat trouble (the most common “easy fix”)

Sometimes the heat pump isn’t the problem—the thermostat is.

What can go wrong:

• Incorrect settings: The system may be set to “cool” or “auto” with a temperature too low to trigger heat.

• Dead batteries or power issues: Some thermostats lose settings or fail to send signals when power is interrupted.

• Loose, corroded, or frayed wiring: If the thermostat can’t send the correct signal to the heat pump, the system may stay in cooling mode.

• Programming errors: Schedules or smart thermostat settings can override what you think you selected.

Quick homeowner checks (safe and simple):

• Confirm the thermostat is set to HEAT (not COOL or AUTO)

• Raise the set temperature 3–5 degrees above current room temp and listen for system change

• If it’s a battery thermostat, replace the batteries

• If you recently had a power outage, reset the thermostat if needed

If everything looks right and you still get cooling, it’s time to have the wiring and controls tested.

2) Reversing valve problems (the “mode switch” of your heat pump)

The reversing valve is what allows your system to change from cooling to heating. If it fails, gets stuck, or the solenoid controlling it malfunctions, your heat pump may remain in cooling mode.

Signs this could be the issue:

• Thermostat is calling for heat, but the system keeps cooling

• You notice inconsistent switching between modes

• The system behaves normally otherwise, but mode selection doesn’t “stick”

In some cases, the solenoid (the electrical component that shifts the valve) can be repaired. If the valve itself is stuck due to mechanical failure, it may need replacement.

3) Refrigerant leak (a system-wide problem that affects both heat and cool)

Refrigerant is essential for both heating and cooling. Your system shouldn’t “use it up”—so if refrigerant is low, it usually means there’s a leak.

When refrigerant levels drop, your heat pump may:

• Struggle to switch modes properly

• Run longer while delivering weak heating/cooling

• Blow air that feels lukewarm

• Ice up (especially on coils or lines)

Important: Refrigerant issues aren’t DIY. Running a heat pump with low refrigerant can stress major components and lead to bigger repairs. A technician will need to locate the leak, repair it, and restore correct refrigerant charge.

4) Electrical or control board issues (common after storms or wear)

San Antonio weather can include storms and power fluctuations, and HVAC systems depend on stable electrical operation. Electrical faults can prevent the correct signal from reaching the reversing valve or other controls.

Possible causes include:

• Failing capacitor or contactor

• Control board problems

• Damaged wiring between thermostat and system

• Low voltage issues

These problems often show up as “weird system behavior” that doesn’t match thermostat commands—like staying in cooling mode even when heat is selected.

Should you turn the system off?

If your heat pump is blowing cold air while you’re trying to heat the home, it’s usually smart to turn it off and call for service—especially if you suspect refrigerant issues or hear unusual noises.

You can also switch to an emergency heat setting only if your system has it (and you’re sure it’s configured correctly), but don’t rely on emergency heat long-term—it can be more expensive to run.

Heat pump repair in San Antonio: when to call Cowboys AC

Call (210) 495-7771 if:

• Your heat pump won’t switch to heating mode

• The system runs but doesn’t warm the home

• You’re getting cool air in heat mode

• You notice icing, hissing, or unusual noises

• Your thermostat settings appear correct, but performance doesn’t match

Cowboys Air Conditioning & Heating provides heat pump repair and HVAC service in San Antonio and nearby communities, including Stone Oak, Alamo Heights, Castle Hills, Shavano Park, Leon Valley, Terrell Hills, and Downtown San Antonio—with 24/7 availability for urgent HVAC issues.

Schedule heat pump service today

When your heat pump won’t switch to heating mode, it’s often a controllable issue—but waiting can increase wear, raise repair costs, and keep your home uncomfortable longer than necessary.

For fast, professional heat pump repair in San Antonio, TX, call Cowboys Air Conditioning & Heating at (210) 495-7771 to schedule an inspection and get your heating back on track.