For Service Call: (410) 381-7991

Carrier Factory Authorized Dealer
E S A Technician working on a furnace

Frequently Asked Questions

Do I Have a Problem?

•  There's ice on my heat pump.
The outdoor coils of a heat pump maintain a temperature below 32° F during normal heating operation. Because of this, any moisture in the air will tend to cause frost and ice to form on the coils. The more humid it is outside (misty, rainy or sleeting conditions are the worst), the more frost will form on the unit.
The heat pump has a defrost cycle built into it. During the defrost cycle, the heat pump melts off any accumulated frost.
If the frost on your heat pump
  • never seems to go away,
  • continues to get thicker,
  • or, turns to solid ice that doesn't melt,
there is probably a malfunction in the defrost cycle.
If you have these symptoms, contact us for service.
•  Steam is rising from my heat pump.
All heat pumps have a defrost cycle built into them to eliminate the normal build-up of frost and ice that occurs during the heating cycle.
The typical design, a time and temperature defrost, operates in the following manner:
  • A sensor measures the operating temperature of the outdoor coils. If they are below freezing, an internal clock will send the unit into defrost every 90 minutes (actual running time).
  • During defrost, the outdoor fan stops, the compressor keeps running and the unit switches over to the air conditioning mode. This causes the outdoor coils to heat up, melting off any frost and ice that may have accumulated.
  • The back-up electric heating coils in the furnace come on to maintain the temperature in the house while the system is in the air conditioning mode. The blue or green light on your thermostat will indicate that the back-up heat is running.
  • The defrost cycle will typically last until the coils reach a predetermined temperature, or 10 minutes, whichever comes first.
During this defrost period you may see what looks like clouds of smoke pouring off the outdoor unit. This is actually steam, a perfectly normal result of the heated coils melting the frost. This phenomenon will be even more pronounced during rainy or humid conditions.[Top]
•  Nothing on my heating or cooling system is working.
If nothing at all on your system is working, you most likely have an electrical problem in the system.
  • Check all circuit breakers. Sometimes breakers can be tripped even though they look like they are on, so make sure to reset the breakers for your system by turning them all the way off and then back on again.
  • Check to make sure that no other power switches have been turned off. Many gas or oil furnaces have power cut-off switches mounted at the top of the basement stairway, or on the side of the furnace.
If all switches and breakers seem fine, you will need to schedule a service call.
•  My unit is making an odd noise.
In general, the only noises to be immediately concerned about are banging, scraping, clanging, or loud vibration noises. Humming, buzzing and pressure relief noises are normal.
If you hear loud noises coming from either your indoor or outdoor unit, turn the system off immediately to prevent further damage.
  • If the indoor unit sounds like the blower fan is hitting, scraping or vibrating unusually loudly, shut the system off and call for service. Without a functioning blower fan to circulate the indoor air, you will not have heating or cooling.
  • If the outdoor unit is making this type of noise it may be a cracked or iced fan blade that is spinning off-balance.
If the outdoor unit is making noise during. . .
summer sun
  1. Turn the system to "OFF" at the thermostat.
  2. Call for service.
winter sun
sunny weather
  1. Set the thermostat to "Emergency Heat", to turn off the outdoor unit.
  2. Call for service.
snow and ice
rainy or snowy weather
  • If you see ice forming on the top of the unit:
    1. Switch the system to "Emergency Heat" at the thermostat.
    2. Wait until the sun melts the ice off the top and try turning the system back to "Heat."
    3. Listen for the outdoor unit to come on and if you still hear a noise, turn the system back to "Emergency Heat", thereby shutting off the outdoor unit.
    4. Call for service.
  • If you don't see any ice on the unit:
    1. Set the thermostat to "Emergency Heat", to turn off the outdoor unit.
    2. Call for service.

•  The auxiliary (back-up) light on my thermostat is on all of the time.
The auxiliary heat light on your thermostat (usually green or blue, depending on the brand) is a signal that the back-up electric coils in your furnace are energized.
There are three situations when this should occur:
  • Whenever the heat pump is in a defrost cycle, the system brings on the back-up heat. This compensates for the fact that during defrost, the system is actually in the air conditioning mode for a short period of time.
  • The back-up heat also comes on whenever the temperature in the house falls more than 2 degrees below the thermostat heat setting. Similarly, if you raise the thermostat more that 2 degrees, the back-up heat will come on until the room temperature reaches the thermostat request.
  • The colder the outside temperature, the more often you will see the auxiliary heat light come on. This is because in colder temperatures, the outdoor unit cannot produce enough heat by itself to maintain the indoor temperature.
Below outdoor temperatures of 35 - 40° F, you should expect to see the auxiliary heat light turning on and off on a regular basis. If the light seems to be on more than usual during milder weather, it may be a sign that the outdoor unit is not operating properly.
Check to make sure the outdoor unit is running when the heat is on, if not check the circuit breakers. If the outdoor unit is running, and you still think there is a problem, contact us to schedule a service call.[Top]

  • If your outdoor unit is not coming on, check the circuit breaker in your panel box. The problem may simply be a tripped breaker. This is a common problem after electrical storms.

  • Environmental Systems Associates, Inc.
  • 9375-J Gerwig Lane, Columbia MD 21046
  • Lic. HVACR MD 01-2939