(707) 584-7727
ASE CERTIFIEDCLIMATE CONTROL EXPERTS

Auto Heating & AC Repair in Rohnert Park & Sonoma County

Rohnert Park Transmission & Auto Repair provides complete heating and air conditioning repair including AC recharge, compressor replacement, heater core service, and climate control diagnostics by ASE certified technicians.

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(707) 584-7727

Mon-Thu: 7:30am-5pm | Fri: 7am-4pm

ASE Certified
EPA Certified Refrigerant Handling
BBB A+ Rating
Family-Owned Since 1997

AC Repair & Recharge

When your air conditioning stops blowing cold in the middle of a Sonoma County summer, you need it fixed fast. The most common cause of weak or warm AC is low refrigerant due to a leak somewhere in the system. Other common failures include a worn compressor, a bad compressor clutch, a clogged or damaged condenser, expansion valve failure, and electrical issues in the control circuit. Our technicians use professional-grade recovery and recharge equipment to handle both R-134a and the newer R-1234yf refrigerant used in most vehicles from 2017 onward.

Every AC service at our shop includes a complete system evaluation: we check refrigerant levels, test compressor operation, inspect the condenser and evaporator, check for leaks using UV dye or electronic detection, and verify proper airflow through the cabin. Simply topping off refrigerant without finding the leak means the problem will return. We identify and repair the root cause so your AC stays cold through the hottest days. Whether you need a simple recharge, a compressor replacement, or a complete system overhaul, our ASE certified technicians have you covered.

AC Repair

Compressor, condenser, evaporator, and leak repair

AC & Heat Repair

Combined HVAC diagnostics and service

Heater Repair & Heater Core Service

Your vehicle's heater uses hot engine coolant flowing through a small radiator called the heater core, located inside the dashboard. A blower motor pushes air across the heater core and into the cabin through the vent system. When your heater blows cold air, the problem typically lies in the cooling system, the heater core itself, or the blend door actuator that controls airflow direction.

A clogged heater core restricts coolant flow and reduces heating output. A leaking heater core can cause a sweet smell inside the cabin, fogged windshield, or damp carpet on the passenger side. A stuck thermostat that stays open prevents the engine from reaching operating temperature, so there is never enough heat to warm the cabin. Blend door actuators are small electric motors that direct airflow between hot and cold, and when they fail, you may get heat on one side but not the other, or no temperature control at all. We diagnose heater problems systematically, starting with the simplest and least expensive possibilities before recommending major repairs.

Heater Repair

Heater core, thermostat, blend door, and blower motor service

Coolant System Service

The cooling system is the shared foundation between your engine's temperature management and your cabin heating. Coolant circulates from the engine through the radiator (to shed heat) and through the heater core (to warm the cabin). A properly maintained cooling system keeps your engine at the right operating temperature and ensures your heater works when you need it. Low coolant, a failed thermostat, or a clogged radiator affects both engine health and cabin comfort.

We provide complete coolant system service including coolant flushes, pressure testing for leaks, thermostat replacement, radiator repair, water pump service, and hose replacement. Coolant degrades over time, losing its anti-corrosion additives and ability to transfer heat efficiently. Most manufacturers recommend a coolant flush every 30,000 to 50,000 miles. If your temperature gauge runs hotter than normal, your heater output is weak, or you see coolant puddles under your vehicle, bring it in for a cooling system evaluation.

Coolant System Service

Coolant flush, pressure test, thermostat, and hose service

The cooling system also falls under our Engine Repair & Service category, which covers radiator repair, water pump service, and engine overheating diagnostics.

Climate Control Diagnostics

Modern vehicles use sophisticated electronic climate control systems with multiple sensors, actuators, and control modules to maintain cabin temperature automatically. Dual-zone and tri-zone systems allow different temperatures for the driver and passengers, controlled by blend door actuators, temperature sensors, and sunload sensors. When these electronic components fail, you may experience inconsistent temperatures, one side blowing hot while the other blows cold, clicking sounds from behind the dashboard, or complete loss of automatic temperature control.

We diagnose electronic climate control problems using manufacturer scan tools that communicate with the HVAC control module to read fault codes and command actuator tests. This allows us to isolate whether the issue is a sensor, actuator, wiring, or control module problem without removing unnecessary dashboard components. Common electronic HVAC repairs include blend door actuator replacement, temperature sensor replacement, mode door actuator service, and control module reprogramming. Our systematic diagnostic approach saves you time and money by identifying the exact failed component.

Related Services & Resources

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Helpful Guides

Frequently Asked Questions: Heating & AC Repair

Why is my car AC blowing warm air?
The most common reasons your AC blows warm air include low refrigerant from a leak, a failed AC compressor, a bad compressor clutch, a clogged condenser, a faulty blend door actuator, or a blown fuse. Low refrigerant is the most frequent cause. Our technicians perform a complete system evaluation to identify the root cause before recommending repairs. Call (707) 584-7727 to schedule an AC diagnostic.
How much does an AC recharge cost?
AC recharge cost depends on your vehicle's refrigerant type (R-134a or R-1234yf) and the amount needed. R-1234yf, used in most vehicles from 2017 onward, costs more than R-134a. A simple recharge addresses the symptom, but if your system is low on refrigerant, there is likely a leak that needs repair to prevent the problem from recurring. We include a leak check with every AC service.
Why is my car heater not working?
A car heater that blows cold air is typically caused by low coolant level, a stuck thermostat that stays open, a clogged heater core, a failed blend door actuator, or air trapped in the cooling system. The heater core uses hot engine coolant to warm the cabin, so any problem in the cooling system can affect heating performance. A stuck-open thermostat is one of the most common causes, preventing the engine from reaching normal operating temperature.
How often should I recharge my car AC?
A properly sealed AC system should not need regular recharging. If your AC needs refrigerant, it means there is a leak somewhere in the system. Small leaks can develop at O-ring seals, hose connections, the condenser, or the compressor shaft seal. Rather than simply topping off refrigerant repeatedly, we recommend finding and fixing the leak so your AC stays cold indefinitely.
What is the difference between freon and R-134a?
Freon (R-12) was the original automotive refrigerant but was phased out in 1994 due to ozone depletion. R-134a replaced it and was the standard refrigerant until around 2017. Newer vehicles use R-1234yf, which has an even lower environmental impact. Each refrigerant requires specific equipment and cannot be mixed. If your older vehicle still uses R-12, we can convert it to R-134a. We service all refrigerant types.
Is it safe to drive without AC?
You can drive without AC, but it affects comfort and safety. In Sonoma County summers, cabin temperatures can exceed 120 degrees Fahrenheit with no air conditioning, leading to driver fatigue and slower reaction times. If your AC compressor has seized, continuing to drive with the AC belt engaged can damage the belt and other engine accessories. We recommend getting AC issues diagnosed promptly, especially before summer heat arrives.
How much does heater core replacement cost?
Heater core replacement is one of the more labor-intensive HVAC repairs because the heater core is located deep inside the dashboard on most vehicles. The part itself is relatively inexpensive, but accessing it often requires removing significant dashboard components. Cost varies significantly by vehicle make and model. We provide a detailed estimate specific to your vehicle before beginning work. Call (707) 584-7727 for a quote.
What causes a burning smell from my car vents?
A burning smell from the vents can have several causes. A sweet, syrupy smell indicates a leaking heater core, which allows coolant to enter the ventilation system. A burning dust smell when first turning on heat in fall is usually normal dust burning off the heater core. An electrical burning smell could indicate a failing blower motor or resistor. An acrid chemical smell may indicate an overheating AC compressor clutch. Any persistent burning smell should be diagnosed promptly for safety.

Stay Comfortable Year-Round

Whether your AC is blowing warm in summer or your heater is not working in winter, our ASE certified technicians diagnose and repair all automotive climate control systems. Quality parts, honest diagnostics, and warranty protection. Family-owned and trusted in Rohnert Park since 1997.

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305 Laguna Dr, Rohnert Park, CA 94928Mon-Thu 7:30am-5pm | Fri 7am-4pm