AC Runs but Heat Is Dead? A Low Voltage Wiring Heating Repair in Tampa, FL 33603

A Tampa homeowner on N Florida Ave had a package unit that cooled fine but made no heat. Our tech Barbaro G. traced it to a shorted control wire and finished the low voltage wiring heating repair in Tampa in 39 minutes. No compressor failure, no heat strip, just a damaged cable in the 33603 ZIP.

Why does my AC work but not the heat on a package unit?

Because heating and cooling run on separate low voltage control signals. A package unit uses a 24-volt control circuit to tell the system which mode to run. If the wire carrying the heat-call signal shorts out or breaks, heat dies while cooling keeps working normally. That split is exactly what stranded this Tampa, FL 33603 homeowner with cold air on a January morning.

Key takeaways

• Heat dead, AC fine usually means a control issue, not a failed compressor or heat strip.
• Low voltage wiring carries the on or off commands. Damage it and the system cannot follow the thermostat.
• Intermittent heat is a classic short. Works briefly, then quits as the wires shift and touch.
• This repair took 39 minutes because the fault was accessible and the rest of the unit checked out.
• FREE diagnosis. We found the fault and quoted it before any approved-repair labor.

The symptom that came in: cooling fine, heat gone the next morning

The homeowner set the thermostat to heat, and at first it seemed to work. The package unit ran, the blower kicked on, and warm air came out. By the next morning there was no heat at all, even though cooling mode still ran perfectly.

That pattern is a strong tell. When a system works intermittently and then quits, we stop thinking about big mechanical parts and start looking at the control side: the thermostat signal, the low voltage wiring, and any safety controls that might be locking the unit out. A total compressor failure does not let cooling keep running while only heat disappears.

How did the tech find the fault on this no-heat package unit?

Barbaro started by listening to how the homeowner described the failure, then opened the control compartment on the package unit. His inspection focused on three things:

• The thermostat call for heat. Confirming a clean heat signal was actually leaving the thermostat.
• Low voltage wiring inside the cabinet. Checking for loose terminals, damaged insulation, or wires making on-and-off contact.
• The cable run to the condenser section. Inspecting where the low voltage cable could have rubbed, pinched, or weathered.

He found two issues. Inside the unit, low voltage terminals were giving false contact, making the heat work one minute and fail the next. Outside, the protective jacket on the low voltage cable had worn away and the bare conductors had rubbed together, shorting whenever they touched. A short like that can blow the small control fuse on the board or simply make the heat signal unreliable.

What did the low voltage wiring heating repair in Tampa involve?

Once Barbaro confirmed the problem was wiring and not a major component, he did a focused, cost-effective repair:

• Shut off power and secured the wiring compartments.
• Traced every low voltage run inside the cabinet and out to the condenser, marking each damaged section.
• Cut out the compromised cable, re-spliced with proper connectors, and restored insulation so nothing rubbed bare edges.
• Re-terminated the loose internal connections that were causing false contact.
• Restored power, switched to heat, and watched the full sequence to confirm clean, steady operation in both heating and cooling.

He also told the homeowner that when a system has been unable to run for a while, an unrelated issue can occasionally surface once it is working again. If that happens, it gets its own estimate. Being upfront avoids surprises.

Why Tampa’s climate wears low voltage wiring out faster

Outdoor package units in Tampa sit fully exposed to sun, humidity, and the salt air off the Bay all year. UV exposure degrades wire insulation, and vibration accelerates wear wherever a cable touches a sheet-metal edge. We see this pattern most on units past seven or eight years old that have never had the low voltage connections inspected. The thermostat side of the system is documented in the U.S. Department of Energy’s guidance on thermostats, which depends on that low voltage circuit working correctly to control the equipment.

How the failure shows up:

Electrical work on these circuits is best left to a licensed tech. The U.S. Consumer Product Safety Commission’s electrical safety guidance is a good reminder of why DIY taping over damaged wiring is not a real fix.

How Tampa homeowners can catch this before they lose heat

• Schedule annual HVAC maintenance. A tech can spot worn insulation and loose terminals before they fail. Our HVAC maintenance checklist for homeowners covers what should be checked.
• Keep landscaping clear of the outdoor unit. Vines and weeds rub on cables over time.
• Do not ignore intermittent behavior. Works sometimes, then stops is the signature of a control or wiring fault.
• Test heat early in the season. Many Tampa homeowners only try the heat on the first cold morning. See our air conditioning maintenance guide for Tampa Bay for seasonal checks.
• Know your system type. Our overview of HVAC system types for Tampa Bay homeowners helps you describe problems clearly when you call.

If your heater quits, we handle heating repair across Tampa the same way Barbaro handled this one: diagnose first, quote clearly, then fix.

AC running but no heat in your Tampa home? Call Home Therapist at (813) 343-2212 for a free diagnosis from a licensed local tech.