Climate Control
Car Heater Repair & Diagnosis
Three Systems. One Symptom. Proper Diagnosis Matters.
Why Is My Car Heater Blowing Cold Air?
That's why proper diagnosis matters. A thermostat problem looks the same as a blend door actuator failure from the driver's seat, but the repair is completely different. We check all three systems to find the actual cause before recommending repairs. No guessing. No parts-swapping at your expense.
What Controls Your Cabin Heat?
Three systems that must work together
Thermostat stuck open, low coolant, water pump failing, coolant leak, or air pocket in system.
Heater core plugged or leaking, blend door stuck, blend door actuator failed, mode door problems.
Blend door actuator failure, temperature sensor malfunction, control module issues, wiring problems.
Why Heater Diagnosis Takes Time
A proper heater diagnosis means checking:
• Engine operating temperature
• Coolant level and condition
• Both heater hoses (are they both hot?)
• Blend door actuator operation
• Climate control module communication
• Scan tool data from HVAC system
• Airflow from different vents and settings
The symptom 'no heat' could be a $30 thermostat or a $1,500 heater core replacement. We figure out which one before you spend money.
No Guessing
We test all three systems before recommending repairs
Accurate Quotes
Know the real cost before work begins
Right Repair First Time
No parts-swapping at your expense
Alberta Winters and Your Heater
What happens at -30°C that doesn't happen at -5°C:
• Weak thermostats can't maintain temperature against extreme cold
• Marginal coolant flow becomes inadequate
• Blend door actuators that 'mostly work' fail completely when plastic gets cold and brittle
• Heater cores with partial blockage can't keep up with the demand
• Block heater circuits get stressed from constant use
A heater that 'kind of works' in November may completely fail in January. If you notice reduced performance early in the season, get it checked before you're stuck in a deep freeze.
The Heater Core Reality
The heater core itself is inexpensive — Usually $100-$300 for the part.
The labor is not — On most vehicles, the entire dashboard must be removed to access it. This is a 6-12 hour job depending on the vehicle.
What's involved: Drain coolant, evacuate A/C system, remove steering column covers, remove instrument panel, remove center console, disconnect wiring harnesses, remove HVAC housing, split housing to access heater core, replace core, reassemble everything, recharge A/C, refill and bleed coolant, test entire system.
Our recommendation: If we're going that deep into the dash, we'll advise you on whether it makes sense to replace the evaporator core (A/C) at the same time. Same labor to access—doing both now avoids paying that labor twice later.
Signs Your Heater Needs Attention
Get it checked if you notice any of these
No heat at all when the heater is turned up
Heat works sometimes but not others
Only one side blows warm (dual-zone systems)
Clicking or ticking from behind the dashboard
Sweet coolant smell indicates a leak
Windows fog up and won't clear properly
Frequently Asked Questions
Common questions about car heater problems
Why is my car blowing cold air when the heat is on?
Three systems control cabin heat: engine cooling (thermostat, coolant, water pump), HVAC mechanical (heater core, blend doors), and electronic controls (actuators, sensors, modules). We diagnose all three to find the actual cause before recommending repairs.
How much does heater repair cost?
It depends entirely on the cause. A thermostat replacement is a few hundred dollars. A blend door actuator might be $300-600 depending on location. A heater core replacement can run $800-1,500+ because of the labor involved in removing the dashboard.
Why is heater core replacement so expensive?
The heater core itself is relatively cheap ($100-300). The expense is labor—on most vehicles, the entire dashboard must be removed to access it. This takes 6-12 hours depending on the vehicle, and often requires evacuating the A/C system as well.
My heater works on the highway but not in town. Why?
This usually indicates low coolant, a failing water pump, or a partially clogged heater core. At highway speeds, the engine runs harder and pushes more coolant through. At idle, there's less flow, so marginal problems become obvious.
I hear clicking behind my dashboard. What is it?
Usually a blend door actuator. These small electric motors move the doors that direct airflow and mix temperatures. When the plastic gears wear out, they click repeatedly as they try (and fail) to find position. Eventually they'll fail completely.
Can I just bypass the heater core?
Technically yes—the heater hoses can be connected together to bypass a leaking core. But then you have no cabin heat at all, and in Alberta, that's not practical. It's an emergency measure, not a fix.
Book Your Heater Diagnosis
Don't wait until it's -30° to find out your heater doesn't work.