6 Questions to Pinpoint Heater Trouble

A cold winter day isn’t anyone’s favorite time to troubleshoot a faulty heater. But the alternative – a cold cab and fogged up windshield – can’t be ignored for long.

Unfortunately, a driver might not notice a heater problem until outside temperatures are at their lowest. That’s because the colder it is outside, the more quickly the warm air inside the cab moves to a cooler area. To try to determine what’s causing the problem, turn the heater on and ask yourself these six questions:

  1. Is the airflow strong or weak? Hold your hand in front of each vent. If the airflow doesn’t feel as strong as usual or isn’t steady, you may have a clogged air filter. If airflow in the cab doesn’t improve after cleaning or replacing a filter, a faulty blower motor may be to blame.
  2. Is the fan blowing at only one speed? This can be a sign of a faulty blower motor resistor or switch.
  3. Is the airflow cold? If the air coming out of a vent feels cold, the heater core may have a hole that’s allowing warm air to escape. To fix the job right, you’ll want to replace the heater core.
  4. Is the windshield fogged up? Glass that suddenly fogs up is usually a symptom of a leaky heater core, and the condensation that accumulates on glass is usually caused by hot coolant vapor.
  5. Do you smell a sweet odor? A broken heater core allows coolant to seep out. If you smell a sweet or damp odor in the cab, check under the vehicle for signs of a coolant leak. Also feel the passenger-side floorboard for dampness, as this can lead to corrosion.
  6. Are you constantly adding coolant? If a vehicle requires more and more coolant, it may have a leaky heater core.


Count on Road Choice® heating components to deliver the warmth your drivers want, even in extreme weather conditions, while keeping your repair costs reasonable. That’s because every Road Choice blower motor and heater core is built with the highest-quality materials to meet or exceed OEM specifications – all at a value price.For the latest cross-reference information, check out the Road Choice HVAC catalog. You can also search the entire Road Choice parts lineup by clicking on the “Find Parts” icon at the top of the page. Or explore our network of more than 500 North American retailers to find one near you.