Outdoor unit won't come on:
This is a very common problem, whether it's an air conditioner or a heat pump. And there are many things that can prevent the outdoor unit from starting, some of which can be quite serious.
Unfortunately, many times a service technician is dispatched only to find a simple problem that could have been addressed, even fixed by the homeowner.
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
- Faulty thermostat
- Faulty contactor
- Faulty time-delay relay
- Faulty thermostat cable
- Unit off due to an open safety device (low pressure, low temp, high pressure, high temp...)
- Faulty control module
- Thermostat not set properly
- Emergency or shut-off switch turned off
- Blown fuse in panel box
- Circuit breaker tripped or off
- Outdoor disconnect off
- Condensate pump unplugged and/or safety switch open
- Outdoor reset button tripped
- Unit "locked-out"
The bottom causes in blue (shown above) are commonly found problems and can be addressed by the homeowner.
Here is a checklist to go through before making a service call:
- Make sure there is a call from the thermostat.
- Make sure no Emergency switches are off (including the furnace switch).
- Make sure the breakers for the indoor and outdoor equipment are in the "on" position - reset if necessary.
- Make sure the outdoor disconnect is on. Some have a pull-out plug that can be put in upside down preventing the unit from starting. Some have internal fuses or circuit breakers. If you know how to check fuses you may do so.
- If you have a condensate pump with a safety switch, check to see if the pump is completely full of water. If so, make sure pump is plugged-in and hose isn't clogged (could be a bad pump). Condensate pumps can usually be found near the indoor unit.
- If your outdoor unit has a "Reset Button" press it. If that was the problem and you have to press it a second time, then there is a problem and a service call will be needed.
- Your unit could have a safety device locking it out. Reset it by turning the system off at thermostat or breaker, wait 1 minute and turn back on. Wait up to 10 minutes to see if outdoor unit starts.
Please keep in mind that the information found on our website is provided free of charge and Hannabery HVAC does not assume any liability resulting from the information we provide. We hope this information helps, but please note that these are just rough guidelines, and not all possible situations are covered. Your HVAC system should be inspected and repaired by a trained technician.