Weak cabin heat is a common complaint, but real-world diagnostics show the heater core is often blamed when it isn’t the real problem. In many cases, heater core misdiagnosis stems from overlooked issues like low coolant temperature, restricted coolant flow or poor airflow.
Weak cabin heat is often caused by stuck-open thermostats, air trapped in the cooling system, worn water pumps, clogged cabin air filters or blend door actuator failure that prevents proper air mixing. Effective automotive heater system troubleshooting requires technicians to verify engine operating temperature, coolant circulation and airflow before tearing into the dash.
This Tech Tip Short walks through practical no-heat HVAC diagnostics and highlights common coolant flow heating problems that mimic core failure. Watch the full short to sharpen your diagnostic process and avoid unnecessary, labor-intensive repairs, then visit AutoZonePro.com for more information.
About the Author
Erik Screeden
Technical and Multimedia Content Director
Erik Screeden is the Technical and Multimedia Content Director for the Vehicle Service & Repair Group. Erik is an ASE Master Automobile Technician with L1, and L4 credentials, who has been in the industry for over 25 years in various capacities. During that time, Screeden was a technician. He started out at a Ford dealership and continued to several independent repair facilities as well as spent time in the specialty aftermarket at a GM-specific performance shop. After his time as a technician came to an end, Screeden transitioned into a role providing scan diagnostic and J2534 tool support. He was then able to parlay his experience as a technician and a support specialist and use that in several technical sales roles.
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