Commercial HVAC, Rooftop Package Unit (RTU) & Split-System Repair in Knoxville, TN
When a rooftop package unit (RTU), commercial split system, or restaurant make-up air unit goes down, dining rooms overheat, kitchen humidity spikes, and tenant operations grind to a halt. JW HVACR LLC diagnoses and repairs commercial rooftop units, 3-phase compressors, economizers, and commercial gas/electric heating circuits within 60 miles of Knoxville—backed by our 90-Day Repair Warranty.
Based at 823 Reed Dr, Powell, TN 37849 • Office hours 8:00 AM–5:00 PM Mon–Fri • 24/7 emergency service available after hours
Commercial HVAC & Rooftop Package Unit (RTU) Systems We Repair
We troubleshoot 3-phase electrical controls, rooftop airflow and economizer dampers, commercial gas/electric heating stages, and sealed refrigerant circuits across the Knoxville area.
Packaged Rooftop Units (RTUs) & Economizers
- Single- and multi-stage commercial packaged rooftop units (3 to 25+ tons) serving restaurants, retail plazas, offices, and warehouses
- Supply blower assemblies, drive belts, sheaves, bearings, and motorized outdoor-air economizer damper actuators (
ASHRAE 62.1 & 90.1) - Rooftop condensate traps, drain pans, hail-damaged condenser coils, and high/low pressure safety cutouts
3-Phase Compressors, Contactors, VFDs & Gas Heat
208–230Vand460V3-phase scroll and reciprocating compressors, phase monitors, contactors, and variable-frequency drives (VFDs)- Commercial gas-pack heat exchangers, combustion inducer motors, hot-surface ignitors, flame sensors, and rollout/limit switches
- Electric strip-heat sequencers, fusible links, and EPA Section 608 certified leak repair, recovery, and weighed-in recharge
Commercial Split Systems & Kitchen Make-Up Air
- High-capacity commercial split-system air handlers, rooftop or pad-mounted condensers, and commercial heat pumps
- Restaurant kitchen make-up air (MUA) and dining-room static pressure balancing so hot, humid kitchen air does not overwhelm walk-in coolers and ice machines
- Commercial programmable thermostats, zone dampers, and economizer enthalpy controls
Technical Schematic: Commercial Packaged Rooftop Unit (RTU) Diagnostic Loop
A commercial RTU combines ventilation, 3-phase refrigeration, and gas/electric heating on the roof curb. A failure in airflow, economizer control, or head pressure stops comfort below.
Commercial Rooftop HVAC (RTU) Diagnostic Table: Symptom vs. Repair
Check these safe interior items before climbing a roof ladder, and see how our technician diagnoses the rooftop mechanical or electrical fault:
| Symptom You Observe | Most Likely Root Cause | Safe 5-Minute Manager Check | JW HVACR Diagnostic & Repair |
|---|---|---|---|
| Supply vents blow warm air across the dining room, retail floor, or office | Tripped high-pressure cutout from a dirty condenser coil, failed condenser fan motor, pitted 3-phase contactor, or refrigerant leak | Verify the commercial thermostat is set to COOL below room temperature and check the electrical panel for a tripped 3-pole breaker | Test 3-phase voltage/amperage (OSHA 29 CFR § 1910.303), replace failed contactor or condenser fan motor, clean condenser coil, and check charge |
| Zero airflow from ceiling diffusers even though the rooftop unit hums | Snapped or slipping supply blower belt, seized blower shaft bearing, failed VFD/blower motor, or frozen evaporator coil | Listen for whether the indoor supply fan is running and set thermostat fan to ON for 30 minutes if ice is suspected on the coil | Replace worn belt and align adjustable sheave/pulley, replace failed blower motor or bearing assembly, and restore proper static pressure |
| Building feels muggy and clammy; walk-in coolers and ice machines struggle | Economizer outdoor-air damper linkage stuck wide open, pulling 90°F+ humid Knoxville outside air directly into the return plenum | Check whether interior windows/doors are sweating and whether kitchen exhaust hoods are running with make-up air turned off | Test economizer actuator and enthalpy sensor (ASHRAE 62.1 & 90.1), recalibrate minimum outdoor-air damper position, and balance airflow |
| Commercial gas rooftop unit blows cold air in winter or locks out on ignition fault | Failed combustion draft inducer motor, fouled flame sensor, cracked ignitor, open pressure/rollout switch, or faulty gas valve | Check thermostat heat call and confirm the building's roof gas shutoff has not been bumped closed | Inspect heat exchanger integrity, test inducer draft pressure, clean/replace ignitor and flame rod, and verify manifold gas pressure |
| Water staining ceiling tiles or dripping around a supply diffuser beneath the RTU | Plugged rooftop condensate drain pan, dry or improperly sized negative-pressure P-trap, or frozen evaporator coil thawing out | Place a bucket beneath the drip and turn cooling off if water is near electrical fixtures or POS terminals | Clear algae/sludge from the rooftop drain pan, prime and pitch the condensate P-trap, and verify evaporator airflow across the coil |
Verifiable Technical & Regulatory Standards Cited on This Page
- U.S. Department of Energy (DOE) — Commercial Package Air Conditioning & Heating Equipment Standards (
10 CFR Part 431 Subpart F, §§ 431.91–431.97): Federal energy conservation and efficiency test standards for small, large, and very large commercial package air conditioning and heating equipment (rooftop units). Read 10 CFR Part 431 Subpart F (eCFR) - ASHRAE Standard 62.1 (Ventilation and Acceptable Indoor Air Quality) & Standard 90.1 (Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings): Engineering standards governing commercial outdoor-air ventilation rates, building pressurization, and rooftop air-side economizer controls. Read ASHRAE Standard 62.1 Overview
- U.S. Environmental Protection Agency (EPA) — Clean Air Act Section 608 (
40 CFR § 82.161) & AIM Act Commercial Leak Repair Rule (40 CFR § 84.106): Mandatory technician certification and refrigerant recovery/leak-repair compliance for commercial HVAC and refrigeration circuits. Read 40 CFR § 82.161 (eCFR) · Read 40 CFR § 84.106 (eCFR) - Occupational Safety and Health Administration (OSHA) — Control of Hazardous Energy / Lockout-Tagout (
29 CFR § 1910.147) & Electrical Safety (29 CFR § 1910.303): Federal safety requirements for de-energizing rooftop disconnects, belt drives, and208–460V3-phase commercial HVAC panels. Read 29 CFR § 1910.147 (eCFR) · Read 29 CFR § 1910.303 (eCFR)
Trusted by Knoxville-Area Commercial Facilities & Restaurants
Verified 5.0 ★ Google reviews from local commercial customers in the Knoxville area.
“Fast response and excellent communication. Our walk-in cooler went down unexpectedly and they got us back up and running before we lost product.”
“Reliable service and great attention to detail. Clear diagnosis on our kitchen refrigeration equipment, backed by a warranty.”
Request Commercial HVAC or Rooftop Unit (RTU) Service in Knoxville
Tell us what your rooftop unit or commercial HVAC system is doing (or request a Custom Quarterly Commercial PM Proposal). Sends directly to info@jwhvacr.com—we respond during office hours (8:00 AM–5:00 PM Mon–Fri). For an urgent commercial outage or 24/7 emergency service after hours, call (865) 214-7334.
Rooftop Unit (RTU) or Commercial HVAC Down in the Knoxville Area?
Call JW HVACR LLC at (865) 214-7334. Every commercial repair is backed by our 90-Day Repair Warranty. Office hours 8:00 AM–5:00 PM Mon–Fri, with 24/7 emergency service available after hours within 60 miles of Knoxville.
📞 Call Now: (865) 214-7334