A7 HEATING & A/C // FLAGSHIP DIAGNOSTIC
2018 SUV
3.5L V6 · 60,000 mi · A/C blows warm + high-high gauge pattern
Customer concern
"A/C blows warm air. I can hear the compressor cycling but the cabin won't get cold, even after driving 30 minutes on the highway."
Pre-checks
DTC: None REFRIGERANT TYPE: R-134a per underhood label — OK SYSTEM CHARGE: Compressor clutch engages — OK BLOWER MOTOR: All speeds, strong airflow at vents — OK BLEND DOOR: Goes hot when commanded hot — OK CONDENSER FACE: Clean, no bug/leaf restriction — OK COOLING FAN: Does NOT spin with A/C at idle — FAIL
Compressor's working. Blower's working. Blend door's working. The condenser can't shed heat because air isn't moving across it.
Step 1 · Read the manifold gauges
A/C manifold gauges on both service ports. Engine running, A/C on max, idle, ambient 85°F. Read both sides before you reach for the refrigerant.
Low side
60psi · spec 25–45 HIGH
High side
385psi · spec 200–275 HIGH
Vent delta-T
8°Fdrop · spec 25–35 FAIL
Both low side AND high side are well above spec — a "high-high" pattern. What does it indicate?
Step 2 · Inspect condenser airflow
Underhood at idle with the A/C engaged. The condenser face is clean — but watch the cooling fan.
The cooling fan does not run when A/C is requested at idle. What's the immediate consequence?
Step 3 · Diagnose the fan circuit
Walk the cooling-fan circuit one node at a time. Click each test to read the result — finish with the direct motor test.
FixedIntel Meter · Circuit Tests
Power and ground reach the motor when commanded, but a direct 12V test won't spin it. What does this confirm?
Step 4 · Verify charge, rule out overcharge
Before you blame the airflow side, prove the refrigerant side is clean. Run the identifier and recover the charge to weigh it.
FixedIntel Refrigerant ID + Recovery Scale
Refrigerant ID
Recovered charge
Moisture
Pure R-134a, charge in spec, no moisture. What does this rule out, and what remains?
Step 5 · Root cause
The control side is good, the motor won't turn on a direct feed, and the refrigerant side is clean. Here's the dead fan motor. What's the root cause and the right fix?
Diagnosis Closed.
Cooling fan motor replaced — airflow restored, pressures normalized, cabin gets cold. The A/C system was never opened.
0:00
Time elapsed
0/60
Score
0%
Efficiency
A7 · CLIMATE
Profile +14 pts
Real-shop equivalent
In a real bay, this saves a needless evacuate-and-recharge — no refrigerant recovered and re-sold, no compressor condemned, no expansion valve replaced for a problem that was pure airflow. High-high pressures aren't always a refrigerant story; sometimes the condenser just has no air moving across it. A tech who checks the fans before opening the system is 14% faster on climate work and recovers ~290 billable hours a year. Every scenario sharpens the cert and the daily diagnostic edge.