FixCar Heater Not Working — What It Usually Is
Cabin heat is free engine heat delivered by coolant through the heater core. No heat means coolant isn't hot enough, isn't flowing, or the air is bypassing it.
What it actually turns out to be
| The fix involved | Share of visits* | Typical cost† | Median |
|---|---|---|---|
| Thermostat | 23.9% | $165 – $408 | $262 |
| Blower Motor | 19.9% | $185 – $435 | $287 |
| Module / Actuator | 17.1% | $254 – $696 | $413 |
| Radiator | 9.3% | $189 – $624 | $401 |
| Water Pump | 7.1% | $261 – $651 | $394 |
| Heater Core / Component | 5.3% | $141 – $541 | $279 |
| Hose | 5.2% | $103 – $387 | $207 |
| Switch | 2.5% | $126 – $344 | $216 |
| Radiator Hose | 2.1% | $130 – $386 | $234 |
| Other, rarer causes | smaller shares | varies | — |
*Share of visits whose repair involved this part. Combined repairs count toward each
part involved, so shares overlap and don't add up to 100%. Among visits that ended in a parts repair.
†Middle half of real invoices (25th–75th percentile) when this was the only fix — parts + labor, all vehicle types.
Real repair reports
These are recent, paid visits for this complaint — the words as the owner said them, and what it turned out to be.
Car owners said
“- no heat or a/c”
“Front heater not working”
“Check heater blows cold”
“Test for Heater Inoperable”
“no heat from vents”
“heater fan not working”
What the technician found
“Check for no heat or a/c. tech found blown fuse. after testing tech found blower motor locked up. remove and replace blower motor and fuses.”
“Verified concern found coolant full and both hoses hot. Blend door moveement is normal and does not appear to have a broken door. Tried back flushing the heater core and it did not help.”
“CUSTOMER STATES : No heat from vents cause: Blend door actuator Correction: Removed and replaced blend door actuator.”
“Concern, cause, and correction: customer states: front drivers heated seat doesn't work”
Lukewarm at best
An engine that never fully warms — often with the temp gauge reading low — is a thermostat stuck open. Cheap fix, and it was costing fuel economy too.
Heat fades at idle
Warm on the highway but cool at stoplights is the low-coolant signature: the heater core sits high and starves first. Find where the coolant went before just topping up.
One side hot, one side cold
Split temperatures on dual-zone systems are usually a blend-door actuator — a small motor behind the dash, more labor than parts.
Take this to the shop
The FixDozer Diagnosis Brief puts this page on one printable sheet: what this complaint usually turns out to be, how often, and what each fix should cost — so when the diagnosis comes back, you already know whether the number fits.
Download the Diagnosis Brief (PDF)View it online · Narrow it down for your vehicle