If your heat pump suddenly starts blowing cold air in winter, you’ll want to know why it’s happening and how to fix it as quickly as possible. So, here are some causes of a heat pump blowing cold air in heat mode. Remember that many issues should only be inspected and fixed by heat pump repair services.
Too Cold Outside For The Heat Pump
Heat pumps are effective in keeping your house warm only in certain temperatures. But when the temperatures drop significantly, they may fail to operate or blow warm air. Commonly, air-source heat pumps don’t stay effective when the outside temperature drops below 0°F (-18°C). Some specialized units can work well till -22°F (-30°C).
So, if it’s colder than what your heat pump is designed for, it won’t blow enough warm air, and the air will feel cold. You should switch to a furnace at this point. For the time-being, you should properly block windows and doors with blankets and use space heaters.
The Heat Pump May Be Defrosting
In winter, snow and ice build up on the outdoor unit. There is an automatic defrost mode in heat pumps to remove this snow from the outdoor unit. When the heat pump begins defrost mode, it starts blowing cold or unheated air for 5 to 15 minutes. During this period, it will feel like the heat pump is broken. However, after this period, the heat pump resumes heating.
So, if your heat pump is blowing cold air, wait for 15 to 20 minutes. If it doesn’t resume heating after 20 minutes, there is an issue.
Note that even for defrost mode, many heat pumps turn on auxiliary heating to keep the space moderately warm until the heating kicks back in. You may see AUX on the thermostat. Again, if it stays on for more than 20 minutes, look for issues.
Stuck Reversing Valve
A heat pump can blow warm air in winter and cold air in summer. It shifts its role when you change the mode from cool to heat or vice versa. When you change the mode on the thermostat, a reversing valve inside the outdoor unit of the heat pump switches and changes the mode from cooling to heating or heating to cooling.
If this reversing valve gets stuck or faulty, the heat pump won’t change the mode and will stay on the mode on which the reversing valve is stuck. So, if your heat pump’s reversing valve is stuck on cooling mode, it will keep blowing cold air even when you change the settings on the thermostat to heat mode. Inspecting and replacing a reversing valve requires a professional to call in an expert.
Dirty Air Filters
Air filters keep the heat pump system and your home’s indoor air clean by blocking dust and debris. As they perform this job, they get clogged and must be cleaned or replaced. If the air filters are clogged, they restrict airflow so the heat pump won’t properly blow warm air or may give up due to strain on the system and start blowing cold air.
Therefore, clean the air filters if they are washable ones. If they are disposable filters, replace them.
Incorrect Thermostat Setting
Sometimes, the issue is incorrect thermostat settings. So, check your thermostat. Make sure that it’s set to AUTO, not ON. Because if it’s set at ON, the blower fan will keep working even when the heat pump is not heating. With this, the air from the vents may feel cold in periods when the unit is cycled off.
Moreover, you should still double-check that the thermostat is set to heating mode, not cooling mode. It’s required because some smart thermostats can switch modes automatically.
Faulty Or Dirty Thermostat
A thermostat is the device that directs the components when to start heating and when to cycle off. So, if it’s dirty, miscalibrated, or faulty, it won’t detect the correct temperature. Due to this, the heat pump may blow cold air because the thermostat is incorrectly directing it to.
So, check the thermostat. If you see layers of dust on it. Clean the dust. If its cover is removable, then remove it and gently clean the insides. If the issue doesn’t get resolved, the thermostat may be miscalibrated or faulty, so contact an expert for heat pump repair Port Jefferson.
Dirty Or Blocked Outdoor Unit
Dust, debris, leaves, and snow can block the outdoor unit. This can form layers of these on the condenser coil or block the fan from running. When this happens, the unit gets strained and doesn’t properly warm the house. And if it’s not cleaned when due, the unit can also give up, which means the heat pump will blow cold air.
To avoid this problem, regularly clean the outdoor unit. In winter, snow is a huge factor that can block the outdoor unit so shovel the snow and keep it at least 2 feet away from the unit. However, if there is a lot of ice on the unit, the defrost mode may not be working properly.
Refrigerant Leakage
Refrigerant is the liquid/gas that flows in the coils located in the outdoor and indoor unit, and takes part in heating or cooling, depending on the mode. Due to various reasons, the coil may crack or the connections may become loose, allowing refrigerant to escape. With this, the refrigerant level becomes low and the heat pump can’t work effectively. So, the heat pump won’t heat when required or start blowing cold air.
More signs of low refrigerant levels are ice buildup on the outdoor unit (more than normal), heat pump running constantly, higher energy bills, and the heating performance of the heat pump getting worse over time.
If you suspect that the refrigerant level of your heat pump is low, have an expert check the unit. They will look for problems and if the cause is a leakage, they will fix the cause and then refill the unit.
Leaking Ducts
Ducts are the passageways for the conditioned air. If the ducts are damaged or leaky, warm air may leak outside and the cold air will allow itself in. So, you will feel that the heat pump is blowing cold air when the heat pump is performing its role fine, but the real issue lies within the ductwork that’s leaking.
Other ductwork issues can be poor design, improper installation, clogged air ducts, and others. So, if you notice uneven temperature in different parts of the house, heat pump running constantly without cycling off, higher energy bills, weak airflow from vents, cold drafts when heat is on, and a whistling sound inside the walls, it could be a ductwork issue.
Conclusion
If your heat pump is blowing cold air, check the thermostat settings and make sure the outside temperature is not too cold. Moreover, clean the air filter and the outdoor unit. If it still blows cold air, get help from HVAC companies Huntington.









