1985 Autocar — we work on any truck
If it runs diesel and needs help, we'll show up. Age is not a barrier — classic, vintage, or modern.
Mobile Truck A/C & Heat Repair
Diesel Truck A/C & Heat Repair in Charleston, SC
Cab blowing warm in the Lowcountry heat, or no heat when you need it? We diagnose and repair truck cab A/C and heat on-site — compressor, condenser, blend door, blower, and refrigerant — so the cab is comfortable and you stay in the seat.
- No-cool and no-heat, compressor, condenser, blend door, blower, refrigerant
- Leak checks, evacuate and recharge, and HVAC control diagnosis on-site
- Charleston, North Charleston, Summerville, Goose Creek, Mount Pleasant
Cab HVAC Problems We Fix
A/C and heat, diagnosed at the truck
No-cool / weak A/C
Warm vents, weak airflow, and A/C that quits in traffic traced to charge level, compressor, clutch, or a leak.
Compressor & condenser
Failed compressors and clutches, restricted or damaged condensers, and cooling-fan issues that let the system overheat.
Blend door & controls
Stuck temperature, defrost-only airflow, and HVAC control faults from blend door actuators, heater valves, and control heads.
Blower & no-heat
Dead or one-speed blowers, resistor and module faults, and no-heat from coolant flow or heater core problems.
Why On-Site HVAC Service
A comfortable cab isn't a luxury
In Charleston summers a cab with no A/C is a real problem — it wears out the driver and can shut down a route. And "just add refrigerant" without finding the leak is money down the drain; it'll be warm again in a few weeks.
Lowcountry Diagnostics comes to the truck, checks system pressures, finds the leak, and tests the controls and airflow. You get an honest answer on whether it's a charge, a compressor, a blend door, or a blower — before parts and refrigerant get thrown at it.
Why operators call us
- Mobile service where the truck is sitting
- Testing before parts replacement
- Clear written findings and next steps
- Commercial diesel and fleet-focused support
- 24/7 Charleston-area availability
Our HVAC Process
How we diagnose truck A/C and heat
1. Confirm the complaint
No-cool, no-heat, stuck temperature, or blower issue — we pin down exactly what the system does before testing.
2. Check pressures
High- and low-side pressures show whether the charge, compressor, or a restriction is the problem.
3. Find the leak
Leaks at the condenser, hoses, fittings, or compressor seal are located so a recharge actually lasts.
4. Test controls and airflow
Blend door actuators, blower and resistor, heater valve, and control head are checked for no-heat and stuck-temp faults.
5. Repair and recharge
Failed parts are replaced, the system is evacuated and recharged to spec, and cabin output is verified at the vents.
6. Clear findings
You get a plain-language report of the cause, what was repaired, and the vent temperatures after service.
A/C or heat problem in the Charleston area?
Call or text Lowcountry Diagnostics and we'll get the cab cooling or heating again on-site.
Common truck A/C & heat questions
My truck A/C blows warm — what's usually wrong?
Warm air is most often a low refrigerant charge from a leak, a failed compressor or clutch, a bad expansion valve, or a stuck blend door. We check pressures and look for the leak on-site so you fix the actual cause, not just top it off.
Do you recharge refrigerant and find A/C leaks on location?
Yes. We evacuate, leak-check, and recharge the system to spec at your yard or jobsite. Simply adding refrigerant without finding the leak just buys a few weeks, so we track down where it's escaping first.
Can you fix no-heat or a truck stuck on one temperature?
Yes. No-heat and stuck-temperature problems are often a blend door actuator, a heater control valve, a coolant flow issue, or a control fault. We diagnose the HVAC controls and airflow to find why the cab won't heat or change temperature.
The blower only works on certain speeds or not at all — can you help?
Yes. A blower that quits or only runs on high usually points to the blower motor, resistor or control module, or a wiring and connector fault. We test the blower circuit on-site and repair it. Call or text (843) 310-0995.
Request Truck A/C & Heat Repair
Tell us where the truck is and what the A/C or heat is doing. For a cab that's unbearable to work in, calling or texting is fastest.
Need it cooling today? Call or text (843) 310-0995.
Recent Repair Photos
A look at the repairs we make
Real field photos from Lowcountry Diagnostics — from engine diagnostics and electrical to hydraulic, HVAC, and heavy-duty truck service, handled on-site across the Charleston area.
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