HVAC Technical Training — six learning paths

Homeowner says the air handler is blowing but the house has been getting warmer since yesterday afternoon.

Homeowner reports intermittent no-heat. The furnace lights, runs for a few seconds, then shuts down and tries again.

Homeowner says the system runs all day but barely cools, and the vents feel weak and cold-damp rather than cold and strong.

Homeowner says the system runs all day and the house never gets below 78°F. Another contractor “topped it up” last month and it felt better for a week.

Walk-in cooler is running continuously and only reaching 42°F on a 35°F setpoint. Customer says it used to hold fine.

Walk-in cooler temperature keeps swinging — overshoots cold, then drifts warm, never settles. Customer says they already added charge and it did not help.

Walk-in cooler is running warm and the compressor keeps cutting out on the high-pressure control. The site contact is convinced it just needs gas.

Supermarket rack: one case group is running warm while the other five circuits hold temperature. The night manager wants gas added to the rack; someone on shift has suggested shutting the whole rack down to see if it is that one.

A no-cool call at a small mixed site. One new split system is on an A2L refrigerant, the two older units are legacy A1. You must set safe working practice before you open anything.

Walk-in cooler is running but product temperature is rising. Box is at 48°F, setpoint 35°F.

Ice machine is running but producing little or no ice. Bin is nearly empty.

Prep-table reach-in is warm. Product in the pan rail is above safe temperature.

Walk-in freezer keeps icing up. Product temperature climbs a few degrees each day and the customer has been scraping the coil by hand.

You are called to a small commercial site that has a new hydrocarbon (R-290) reach-in and a CO₂ (R-744) system in the same building. You must decide safe working practice before starting diagnosis.

Retail space is warm. Thermostat is calling for cooling, the supply fan runs, but the air out of the diffusers is not cold.

Rooftop unit is cooling, but energy use is high and the economizer never seems to bring in outdoor air even on mild days.

Retail space is warm at the back of the building. The RTU runs constantly and the store manager says the vents 'barely blow'.

Rooftop unit is not heating. Thermostat is calling for heat. Blower may run, but there is no useful heat from the supply.

New packaged RTU has been set on the curb. Electrical and duct connections are complete. You are called to perform first start-up and basic verification before handover.

“It stopped cooling sometime yesterday. The fan blows but the air is room temperature.”

“It runs all day and the house never really gets cold. It used to shut off by lunchtime.”

“The air coming out is freezing but the bedrooms never cool down.”

“The inside fan runs but the box outside never comes on anymore.”

“There is ice all over the copper at the outdoor unit and water dripping in the closet.”

“Another company put a capacitor in last week. Now it starts, runs a minute, and clicks off.”

“The house stays warm but the electric bill doubled. The little heater light is on all the time.”

“The head runs all the time but the office sits at 28°C. It was fine last summer.”

“The front half of the store is warm. The unit says everything is normal on the display.”

“Two techs have been out. Both said it is working correctly. My staff are standing in 29°C.”

“There is a sharp smell in the plant room and the unit keeps tripping. Can you just braze it up today?”

“We need the start-up sheet signed today so the fit-out can hand over.”