WHAT DOES IT MEAN WHEN MY HEAT PUMP OR AIR CONDITIONER IS ICED-UP IN SUMMER?

It is never normal to see ice in the summer anywhere on a heat pump or a central air conditioner. This includes the indoor unit, outdoor unit and interconnecting line-set. It is possible to ice-up the indoor coil, however, if the air conditioner is running in very cold weather or if the thermostat is turned down extremely low. We recommend never turning the thermostat below 70 degrees. If air conditioning is needed during winter months, such as for restaurants or businesses, then a “low ambient kit” is required, and can be installed by a service technician. If you see ice anywhere on a heat pump or air conditioner during the summer, then there is most likely a problem and you should turn it off immediately. Below is a list of possible causes.

These items usually require a service call:
  • Bad indoor fan motor – not running/running slow
  • Loose, worn or broken fan belt
  • Bad indoor fan relay
  • Extremely dirty blower wheel
  • Low refrigerant charge
  • Restriction
  • Blocked capillary tube
  • Blocked orifice
  • Faulty expansion valve
  • Stuck compressor contactor
  • Faulty thermostat
  • Extremely dirty or damaged indoor coil
These items, however, can be addressed or even fixed by the homeowner:
  • Clogged or blocked air filter
  • Supply and/or return vents blocked or closed
  • Running air conditioner with windows open
  • Setting thermostat too low
One other thing to keep in mind: if you have a central humidifier, make sure it is shut off and if it has a damper – close it for the summer.

WHY DOES MY OUTDOOR UNIT MAKE STRANGE/LOUD NOISES?

Heat pumps do tend to makes strange and/or loud noises at times, more so in the winter. Heat pumps have reversing valves that reverse the flow of refrigerant between the heating and cooling modes.

During the winter, whenever the heat pump goes into the defrost mode, this valve shifts. Along with that comes a “whooshing sound,” which usually lasts for a couple seconds. After that, the compressor sometimes sounds much louder than usual, almost a “tinny sound.” After shutdown the refrigerant pressures equalize, during this period sounds can sometimes be heard, but this is normal.
Another common loud sound is when the outdoor unit starts up or shuts off. Specifically, the newer “scroll” type compressors tend to make a “back-peddling” type of noise on shutdown. On start-up, they sometimes sound like an “out-of-balanced washing machine.”
Sometimes customers complain of a buzzing noise coming from the outdoor unit, even when it’s not running. This is usually the reversing valve solenoid coil. It’s low voltage (24 volts) so it isn’t really wasting energy and sometimes they can be heard.
If you are hearing a very loud “metal-hitting-metal type sound,” the fan blades could be hitting something; possibly ice, a wire or tubing. Take a look and shut the unit off immediately. This almost always ruins the fan blades and possibly the motor as well. If a piece of copper tubing shifted and is being hit by the blades, they could cut a hole in it and cause the refrigerant to leak out. Then there is always the vibration noise, which sounds simple but can be the most difficult to eliminate. Sometimes it is just a matter of installing rubber isolation pads under the unit. Sometimes the refrigerant piping is strapped too tightly to the joists or studs in the home. Sometimes it is in the unit itself and cannot be eliminated.
These items usually require a service call:
  • Bad motor
  • Out of balanced or broken fan blades
  • Low refrigerant charge – can cause “gurgling sounds”
  • Bad reversing valve – passes refrigerant internally, makes “hissing sound”
  • Buzzing contactor or noisy solenoid coil
  • Loud compressor
  • Loud unit
These items can be addressed by the homeowner. Try to check for these conditions first before calling for service:
  • Bad compressor valves
  • Outdoor unit iced-up, fan blades hitting ice (weather-related)
  • Fan blades hitting some other obstruction
  • Vibration due to loose parts
  • Vibration due to refrigerant piping being strapped too tightly

WHY WON’T MY OUTDOOR UNIT SHUT OFF WITHOUT THE USE OF THE CIRCUIT BREAKER?

This happens occasionally. The thermostat reaches the desired temperature, the indoor unit shuts off, the air stops blowing, but the outdoor unit keeps on running. In the heating mode (if it’s a heat pump), it could eventually shut off on a high-pressure safety device. But in the cooling mode, it could run forever unless you turn the breaker off. And this will cause the indoor coil to freeze up into a solid block of ice, and eventually the ice will build up and travel all the way to the outdoor unit.

So what causes this? Only a few things, the most common of which is a stuck compressor contactor – located in the outdoor unit. The contacts tend to get pitted-up. Eventually they can weld shut. This can cause serious damage to the system. It is good practice to replace the contactor every few years or when pitted – just like spark plugs in a car.

Another cause would be a shorted thermostat cable. This can be caused by a weed-whacker hitting the wire outside, or a wire-staple digging into the wire too tightly, rodents chewing on it, or just bad wire.
Lastly, the thermostat itself could be bad, sending a signal to the outdoor unit when it isn’t supposed to.
These items usually require a service call:
  • Stuck compressor contactor
  • Thermostat cable shorted
  • Bad thermostat

HOW OFTEN SHOULD I HAVE MY EQUIPMENT SERVICED?

Heating and air conditioning equipment should be serviced at least once a year. The best scenario is to have the heating system checked in the fall and the air conditioning checked in the spring. Oil-fired equipment should definitely be cleaned and serviced annually; at the beginning of each heating season.

WHY SHOULD I HAVE MY EQUIPMENT SERVICED?

Annual servicing includes cleaning the system, checking for any problems or potential problems and adjusting for PEAK efficiency.

Benefits include:
  • Increased dependability
  • Find potential problems and fix them quickly
  • Provide maximum efficiency which lowers energy costs
  • Prolongs the lifespan of the equipment
  • Maintains safe and healthy operation
  • Can help to protect the environment
  • Drastically reduces the chance of a break-down, which usually happens at night or on weekends when repair rates are higher