The heat pump really is blowing cold air.

The customer just thinks the heat pump is blowing cold air.

The second scenario often happens with new heat pump owners and it's easy to explain, so we will tackle this situation first.

It's quite simple... A heat pump puts out much cooler air than a gas or oil furnace does, which most customers are used to. Furnaces tend to put out about 130 to 140 degree air. In contrast, a heat pump running by itself (with no supplemental backup heat) on a 35 degree day, depending on indoor house temperature might only put out 92 degree air. On a 20 degree day, it might drop to 85 degrees.

Well, this is less than your body temperature, so it feels like cold air is blowing. But, it is still warmer than the indoor house temperature, so it is still putting heat into the house. Unlike a furnace that puts out a lot of heat for short periods of time, a heat pump will put out less heat for longer periods of time.

So if you are new to heat pumps, try measuring the air temperature with an accurate thermometer before calling for service. If there is no difference between the return temperature and the supply temperature then there is a problem.

Below is a list of possible causes. Items in red usually require a service call. Items in blue however can be addressed, some even fixed by the homeowner.

Red = Professional fix | Blue = Homeowner fix

Low refrigerant charge
Refrigerant flow-related problem - restriction/bad metering device
Poor efficiency- needs cleaning and servicing
Bad reversing valve
Bad compressor valves
Compressor not running
Running in A/C mode
Outdoor unit iced-up because of a malfunction

Outdoor unit iced-up - weather related
Snow drift against outdoor unit
Outdoor unit not running
Cold return temperatures - examples: Air handler in attic and return trunk disconnected from unit, pulling in cold attic air. Unit in basement with a basement return and open windows. Thermostat set below 65 degrees.

The bottom four causes in blue are commonly found problems and can be addressed by the homeowner.