Gloved hands reaching into the opened rear panel of an appliance, a row of screwdrivers laid out on a folded towel, a green work light overhead.

Heat, Cooling, and the Line

Filters, thermostats, condensate, coils and blower motors are yours. Gas trains and refrigerant are not. Knowing which is which saves both money and lungs.

Module 4 of 74 lessonsWritten in full1 worksheet

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The lessons

All 4, in the order they are read.

1. The maintenance that is most of it
Filters, coil cleaning and a clear condensate path prevent the majority of the calls a homeowner makes.
2. Thermostats and control wiring
Low-voltage control faults look like dead equipment, and they are the easiest thing in the whole system to test.
3. When it is the gas side
Ignition sequences fail in a readable order, and reading the sequence tells you what to tell the technician, not what to replace.
4. Carbon monoxide and the non-negotiables
The three symptoms that mean you stop, leave and call somebody today, not this weekend.

The worksheet

Seasonal HVAC service sheet

Two columns, spring and autumn. Every row in the top block is homeowner work. Every row in the bottom block is a technician row — you record the date it was last done and by whom, and nothing else.

Seasonal HVAC service sheet
Task	Owner or technician	Spring date	Autumn date	Note
Replace filter, record size	Owner	—	—	—
Clean outdoor condenser coil, clear 600 mm around it	Owner	—	—	—
Clear and flush condensate line and pan	Owner	—	—	—
Check and correct thermostat schedule and batteries	Owner	—	—	—
Inspect and clear return grilles and supply registers	Owner	—	—	—
Test 24 V control voltage at the board	Owner	—	—	—

4 further rows in the downloadable sheet.

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Module 5: Small Engines →