EcoService OS

Residential Over- and Undercharge — Poor Cooling Call

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. Unit: 3.5-ton R-410A split system, fixed-orifice indoor coil, 8 years old. This is a free graded decision lab from Residential HVAC Service & Diagnostics — you choose each next check, readings fill in as you work, wrong turns are coached, and you are scored on cause, efficiency, safety and verification. No login required, about 14 minutes.

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Residential HVAC Service & Diagnostics
~14 min
intermediate

The call

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.

Equipment
3.5-ton R-410A split system, fixed-orifice indoor coil, 8 years old
Ambient
94°F
Site notes
Filter is clean, blower runs, condenser coil looks clean, thermostat calling for cool. Gauges and a reliable thermometer are available.

Decision 1 of 5

The system is running in 94°F ambient and the house is 6 degrees above setpoint. The last visit ended with refrigerant being added.

What do you do first?

Where this lab sits

This is one module lab from Residential HVAC Service & Diagnostics. The full path builds the rest of the diagnostic sequence around it, each module ending in a graded lab like this one.

Open Residential HVAC Service & DiagnosticsNext lab: Residential No-Cool — Split System Not CoolingNext lab: Residential No-Heat — Gas Furnace Short Cycling on IgnitionNext lab: Frozen Coil / Airflow Restriction

Studying for an exam too?

Free practice questions with explained answers, then come back to the labs. Exam preparation only — we do not issue EPA, NATE or other official credentials.

EPA 608 practice testHVAC practice testNATE practice testEPA 608 certification prepA2L refrigerant trainingRefrigeration technician trainingCommercial refrigeration certification prep

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