A lot of Tucson homes heat with the same outdoor unit that cooled them all summer. In heat mode that machine is a heat pump: it moves heat from outdoor air into the house, and on colder nights electric strips inside the air handler back it up. When someone says the system is “blowing cold” in November, they might be feeling a normal heat-pump supply temperature, a defrost cycle, or a real fault. Those three feel similar from the living room and they are not the same repair. Sabino Creek Heating & Cooling works on residential heat pumps across Tucson, the foothills, Oro Valley, Marana, and the southern communities. This page is how we separate a healthy heat pump from one that needs help.
If the house has a gas furnace and the outdoor unit is air conditioning only, you want furnace repair instead. If you are not sure which you have, the nameplate on the outdoor unit and the thermostat modes (Emergency Heat or Aux) usually give it away. Say “not sure” on the estimate form and describe what the outdoor unit does when the thermostat is set to Heat.
What heat-pump air is supposed to feel like
A gas furnace can put very hot air in the ducts. A heat pump usually does not. Supply air in the 85 to 100 degree range is a normal heating temperature for many systems, and it can feel cool on your hand compared with furnace air even while it is warming the house. Give it time. The indoor blower may run before the coil is fully warm, and there is often a short delay after you switch the thermostat to Heat.
Air that stays genuinely cold, room temperature or lower, for a long stretch with the thermostat well above the room is not that normal lukewarm delivery. Neither is an outdoor unit that sits silent while the indoor blower runs and the house never gains a degree. Write down which of those you have before you call it “no heat.”
Defrost is supposed to look a little wrong
In heat mode the outdoor coil is the cold coil. On a damp or chilly Tucson morning it can frost. The control board then runs a defrost: it reverses the refrigerant so the outdoor coil can warm up and melt the frost. During that cycle the outdoor fan often stops, you may see steam, and the indoor supply air can feel cool for a few minutes because the system is briefly in cooling. Auxiliary heat strips often come on so the house does not get a blast of cold air. A defrost that finishes, after which the outdoor fan starts again and the supply air warms back up, is the machine doing its job.
Ice that never clears is different. A coil encased in ice, a grinding noise from the outdoor fan hitting ice, or defrost that seems to run without the ice shrinking means the defrost circuit, the sensors, the outdoor fan, or the refrigerant charge needs a diagnosis. Do not pour water on the coil or chip ice off the fins. Bent fins and a damaged fan blade turn a defrost problem into a bigger repair.
Auxiliary heat and the Emergency Heat setting
Heat strips are resistance heat. They are the backup, and on a hard cold night in the Catalina Foothills or Green Valley they are supposed to help. They are expensive to run compared with the compressor, and they are not a substitute for a heat pump that has quit. If the thermostat shows Aux or Emergency on a mild Tucson evening, around 50 degrees or warmer, and the outdoor unit is not running, the strips may be the only thing heating the house. The room may feel barely warm and the electric bill will show it later.
Emergency Heat, on many thermostats, locks out the compressor on purpose and runs strips only. People flip it during a cold snap and forget. Check that the mode is Heat, not Emergency, and raise the setpoint a few degrees above the room. If the outdoor unit still never starts, that is a repair, not a thermostat preference. A reversing valve that sticks in cooling will blow cold air whenever the system runs in heat, and sometimes the opposite problem shows up as heat when you wanted cooling at the end of summer. Mention whether cooling worked in September. That one fact narrows the fault.
Tucson’s mild winters hide weak heat pumps
The valley does not stay below freezing the way a Midwest winter does, so a heat pump with a tired compressor, a low charge, or a defrost board that never quite cycles can limp through a lot of seasons on strips. You notice it on the first morning that is actually cold, or in a foothills house that drops into the 30s while midtown stays in the 40s. Catalina Foothills and Green Valley both see more heating hours than a central Tucson house that is empty all day. A system that “keeps up” downtown may not keep up in either of those places, and the fix is still a diagnosis of the heat pump, not a bigger thermostat number.
Shoulder season makes this messier. An October afternoon in Tucson can still want cooling while the night wants heat. A heat pump is built for that swing when the reversing valve, the charge, and the defrost controls are healthy. A system that cools in the afternoon and then will not heat at night is a classic reversing-valve or contactor complaint. Tell us both halves of the day on the form.
Filters, airflow, and the indoor coil
Heat pumps are as allergic to a packed filter as furnaces are. Low airflow can ice the indoor coil in heat or in cool, trip safety switches, and make the strips carry a load they should only see in backup. After monsoon season the return filter and the outdoor coil both deserve a look. Clear debris off the outdoor unit, keep a couple of feet of space around it, and do not stack storage against the indoor air handler. If you changed the filter and the outdoor unit is clear and the supply air is still cold in heat mode, stop there. Repeating filter changes will not fix a valve or a charge.
What we need on the form
Send the request from the contact page. Same-business-day follow-up is how we handle estimate requests. Please include the ZIP, whether the outdoor unit runs in Heat, whether you see Aux or Emergency on the thermostat, any ice or steam, and whether cooling was normal at the end of summer. If the system still heats but you want it checked before a cold stretch, ask for a heating tune-up instead of a repair. The first-night checks are on the fall checklist. Neighborhood coverage is on service areas.