A heat pump warms in the winter and cools in the summer. Or at least that’s how it’s supposed to work. This Fix-It Guide on heat pump repair tells how a heat pump works, what often goes wrong, how to identify the heat pump problem, and what parts and tools you will need to fix it. It then gives simple step-by-step instructions for how to clean or replace a heat pump filter, how to oil and adjust the blower unit, and how to restart a heat pump at low temperature. For some situations, this guide refers to electrical service panel repair, forced-air distribution repair, and motor repair.
How Does a Heat Pump Work?
A heat pump is a heat exchanger that removes heat from indoor air to cool it and extracts heat from outside air and pumps it indoors to heat a home. It takes advantage of liquid’s tendency to absorb heat as it expands.
A heat pump has an outdoor unit in which a fan moves air through a coil that absorbs heat. A compressor then super-heats the vapor and sends it through refrigerant lines to a second coil in the interior distribution unit. A blower pushes return air through the coil, warming the air and forcing it into the ducts. Meanwhile, refrigerant travels back to the outdoor unit to begin another full cycle through the pump. An automatic reversing valve reverses these flows as needed to keep the home’s interior comfortable.
What Can Go Wrong with a Heat Pump?
“Why is it cold [hot] in here?” Maybe the heat pump isn’t working as it should. Common symptoms include: The pump may not run, the unit may short cycle, and the automatic defrost cycle may malfunction.
Heat pumps work well down to about 15°F. Below that, most require a backup heating source, usually electric-resistance elements installed in the furnace, ducts, or the pump cabinet. That’s why heat pumps aren’t as popular (or as efficient) in colder climates.
How Can I Identify a Heat Pump Problem?
- If the heat pump does not run, check fuses and breakers (see the Electrical Service Panel Fix-It Guide). Also check the unit to see if it has a reset switch on the outdoor unit.
- If the unit short cycles, clear any debris around the outdoor coil. Also check the filter and blower unit (see below).
- If the defrost cycles last more than 15 minutes or occur more than twice an hour, or ice accumulates on the outdoor unit, check the unit owner’s manual for specific instructions or contact an HVAC (heat-ventilation-air conditioning) technician.
- If your heat pump is off for more than an hour at temperatures lower than 50°F, follow the steps below to re-start a heat pump at low temperature.
- If some rooms are too cool and others too warm, the forced-air distribution system may require balancing.
Outdoor heat pump units can be clogged with leaves or even pests such as squirrel nests. Before starting the system after a lengthy hibernation, make sure you remove the cover and clean out any debris.
What Do I Need for Heat Pump Repair?
Replacement parts for your heat pump are available from the manufacturer or an aftermarket supplier such as an electrical or heating supply store. Here are the basic tools you’ll need to access and maintain a typical heat pump:
- Light oil
- Vacuum cleaner
What Are the Steps to Heat Pump Repair?
Clean or replace a heat pump filter:
- Open the blower access door on the outdoor unit.
- Remove the filter inside the unit by either sliding or unwrapping it. Clean the area with a vacuum or a damp cloth.
- Clean a dry-foam filter or replace other types.
- Install the cleaned or new filter and firmly close the blower access door.
Oil and adjust a heat pump blower unit:
- Visually check the motor and any pulleys for small lubrication ports or holes; they may have an arrow with the word oil nearby.
- Lubricate oil ports with light (SAE-10) lubricating oil.
- If the unit has a belt drive, adjust the belt to be slightly loose but not slipping. If the belt is worn or cracked, replace it. Tighten mounting bolts as needed.
Restart a heat pump at low temperature:
- Turn the system selector switch to emergency heat.
- Wait six hours, then return to the normal heat setting.