Find the right guide for your HVAC problem

EPA Refrigerant Certification Guides

Use these guides to understand the difference between credentials, find official resources, and avoid paying for the wrong program.

• EPA 608 Certification Lookup — find or replace a lost card using the official recovery path.
• EPA 608 Certification Cost — compare legitimate providers and understand the fees to ask about.
• EPA 609 Practice Test — original MVAC study questions and a clear explanation of how Section 609 differs from Section 608.

Popular Troubleshooting Guides

• Furnace Leaking Water — match where the water appears to its likely source, with a labeled diagram.
• Furnace Won’t Ignite — causes and safe next steps when the burners will not light.
• Furnace Not Heating — common reasons a furnace stops heating, from thermostat settings to a dirty flame sensor.
• Daikin Mini Split Blinking Light — how to read A1, C9 and other codes for your model.
• Mitsubishi Mini Split Blinking Light — what each flash count means on MSZ-GL units.

Before You Start

Some HVAC work involves electricity, combustion equipment, pressurized systems, or refrigerants. This site is here to help you understand the issue—not to encourage unsafe repairs. Turn off power when a guide says to do so, follow your equipment manual, and call a qualified professional when a step is beyond a safe homeowner check.

How We Approach Our Guides

These articles are written to be useful, direct, and transparent about the limits of homeowner-level advice. Where a topic involves regulations or certification, we link to the relevant official source. Read our About page, Editorial Policy, and Affiliate Disclosure for more about the site.

Need a Topic Covered?

Found an issue that is not explained clearly here? Contact HVAC Not Heating with the symptom, equipment type, and what you have already checked.