HVAC, Furnace & AC Repair
Sonora & Tuolumne County
When your furnace won't heat or your AC won't cool — we fix it right.
Same-day diagnosis and fast repairs for furnaces, air conditioners, and ductless systems throughout Sonora and Tuolumne County. We find the actual problem, explain what failed, and give you honest repair-vs-replace math — no upselling.
Fast, Honest HVAC Repair — No Runaround
What We Do — Repair Services
Furnace & Heating Repair
- Gas furnace troubleshooting and repair
- No heat / won't ignite issues
- Thermostat problems
- Airflow and blower issues
- Safety inspections
- Emergency heating repairs
When your heat goes out, we respond quickly to diagnose the problem and get you warm again.
Air Conditioning Repair
- AC won't cool or won't turn on
- Refrigerant leaks and recharging
- Compressor and condenser issues
- Fan motor problems
- Frozen coils
- Emergency cooling repairs
We fix what's broken — and explain what failed in plain language.
Ductless Repair & Troubleshooting
- Diagnostic and repair on Bryant and most other ductless brands
- Refrigerant leak detection and recovery
- Indoor coil and filter cleaning
- Outdoor unit service and performance checks
Already have a ductless mini-split? We service Bryant and most other brands.
Need Service Now? Same-Day Heating & Cooling Service
When your heating or cooling system fails, we respond quickly. Call now for Same-day diagnosis and fast repairs. Call us if you're dealing with:
What to Expect When You Call J. Hart
Here's what to expect when you call J. Hart.
Tell us what's going on
Call or request service. We'll ask a few quick questions and schedule the soonest available time — same-day for urgent no-heat and no-AC calls.
We diagnose and explain your options
We find the cause, explain what we see in plain language, and give you clear repair or replacement options.
You approve the work before we begin
No surprises. You'll know what it costs and what's included before we start.
We fix it right, test, and walk you through it
We test our work, clean up the area, and tell you what failed and what to watch for.
Common Heating & Cooling Problems We Fix
If you're dealing with HVAC issues, here's what we see most often in Sonora-area homes and what you need to know.
Furnace Won't Heat
Furnace Won't Heat or Won't Turn On
Most common causes
Thermostat issues
Wrong setting, dead batteries, or a faulty thermostat. We check this first.
Pilot light or ignition problems
Pilot won't stay lit or electronic ignition fails.
Dirty flame sensor
Buildup can shut the furnace down as a safety measure. Simple cleaning often fixes it.
Clogged filter
Restricted airflow can trigger safety shutoffs. Always check your filter first.
Blower motor failure
Heat at the furnace but not throughout the house.
Gas valve or control board
More serious failures that require parts replacement.
What we do
We diagnose systematically — starting with the common causes before moving to complex ones. We test components, identify the actual problem, and explain what needs to be fixed.
Repair vs. replacement
Simple repairs (thermostat, flame sensor, filters) are often $250–$500. Major component failures (blower motor, control boards, heat exchanger issues) can run $500+.
If your furnace is 15+ years old and needs an expensive repair, replacement often makes more financial sense. We'll give you honest guidance.
Why Choose J. Hart for HVAC Repair
Honest diagnostics
We identify the actual problem, not just sell the most expensive solution.
Clear, flat-fee pricing
Our HVAC service call is a $185 flat fee (includes the diagnostic and the first half-hour of work). We explain pricing before any additional work begins.
Four generations local
Family-owned since 1984. Same name on the truck, same accountability.
Licensed & insured
CA Lic #459194 · NV Lic #77957
Serving Sonora, Tuolumne County & Calaveras County
We're based in Sonora and serve homes and businesses across Tuolumne and Calaveras County.
We know the area's homes, building types, water conditions, and climate challenges — and what works at our elevation.
Not sure if we serve your area? Give us a call: (209) 533-1978
"New to Sonora and so thankful for the referral. J Hart is the best in town, not only for plumbing but also HVAC. Brian and JD were thorough, explained everything about both my furnace and water heater; they were professional and showed excellence in customer care."
Wendy Crowley
HVAC & Water Heater · 2025
Frequently Asked Questions
Most repairs are completed in the same service visit. If a part needs to be ordered, we'll let you know before we leave — typical parts turnaround is 1–3 business days. We'll give you a clear timeline so you're not waiting without information.
Usually low airflow (dirty filter, blocked vents) or low refrigerant. Turn the system off, let it thaw, and check your filter. If it freezes again, call us — you likely have a refrigerant leak or airflow issue that needs professional diagnosis.
Furnaces typically last 15–20 years. Air conditioners last 10–15 years. Heat pumps last 10–15 years. Regular maintenance extends lifespan significantly.
If it's under 10 years old and the repair is minor, repair makes sense. If it's 15+ years old, needs frequent repairs, or requires a major component, replacement is usually the better investment. We'll give you an honest recommendation — and if it's time to replace, see our HVAC Installation page.
$185 flat fee (includes the diagnostic and the first half-hour of work). We'll explain pricing before any additional work begins.
Every 1–3 months depending on the filter type, whether you have pets, and how much you run the system. A clean filter is the single easiest thing you can do to prevent problems.
We service most major brands. For new installations, we recommend and install Bryant equipment as a factory-authorized dealer.
Our service area covers Sonora, Twain Harte, Columbia, Jamestown, Tuolumne, Mi-Wuk Village, Pinecrest, Groveland, Chinese Camp, Don Pedro, Sierra Village, Angels Camp, and surrounding communities — across Tuolumne County and Calaveras County.
Ready to Schedule?
We'll Call You Back Fast.
Fill out the form and we'll reach out to confirm your appointment. No holding, no runaround — just a real person who knows your trade area.
- Same-day appointments available Mon–Fri
- Upfront pricing — no surprises after the fact
- CA Lic #459194 · NV Lic #77957
- Hours: 7:30 AM – 4:00 PM, Mon–Fri