The Technician's Ultimate Troubleshooting Guide for Residential Split Systems
Part 1: Initial Assessment and Complaint Verification
The Call
Before you get on-site, gather information:
What's the complaint? Not cooling, short-cycling, not running at all, weak airflow, high bills, noise, or humidity issues?
When did it start? Sudden or gradual?
System age and type? Single-stage, two-stage, inverter, communicating?
Recent service history? Refrigerant charge, compressor replacement, electrical work?
Seasonal pattern? Every summer, specific times of day, after a storm?
This shapes your diagnostic approach. A "not cooling" complaint in peak summer with no recent service likely points to refrigerant or airflow. A "won't run at all" complaint after a storm might be electrical.
On-Site Verification
Never trust the homeowner's description of the problem. Verify the complaint yourself:
Check thermostat settings — Mode (Cool), setpoint, display function. Dead batteries? Wrong mode? Start here.
Run the system — Set thermostat to Cool, setpoint 5°F below ambient. Listen and observe.
Does the outdoor unit start within 3–5 seconds?
Do you hear the compressor? (humming, then clicking start relay, then running hum)
Does the indoor fan start?
Is the system pulling current?
Feel the airflow — Put your hand over supply and return vents.
Is air moving at both?
Is supply air cold or cool?
Weak airflow at startup is normal; it should increase within 30 seconds.
Check pressures and temperature — Connect gauges to service ports.
Note suction and discharge pressures
Measure indoor and outdoor air temperature at coils
Measure liquid and gas line temperature (if accessible)
Ask clarifying questions
How long has it been running and not reaching setpoint?
Does it ever reach setpoint, or is it worse recently?
Does it cool at night but not during the day? (Condenser heat gain issue)
Any recent electrical storms, power outages, or circuit breaker trips?
Part 2: Electrical Diagnostics
If the system won't start or starts intermittently, electrical is your first stop.
Power and Disconnect
Check the disconnect at the outdoor unit. Is it ON?
Verify breaker in the main panel. Is it tripped or OFF? If it trips when you turn on the unit, you have a short or overcurrent condition. Don't keep resetting it—find the problem.
Measure voltage at the outdoor disconnect with a multimeter.
Standard 240V circuits should read 235–245V
Voltage below 220V or above 250V indicates panel or wiring issues
If voltage is low, check panel, breaker connections, and supply wiring for burns or corrosion
Document the voltage—it matters for diagnostics
Thermostat and Control Wiring
Trace the control wiring from indoor to outdoor unit (usually 18 AWG, color-coded).
Visually inspect for damage — Cut insulation, burns, water intrusion, rodent damage.
Check for corrosion at terminals, especially in coastal areas. Salt air corrodes copper quickly.
Verify continuity from thermostat to outdoor unit with a multimeter (resistance should be near zero).
Check thermostat functionality — Does it call for cooling? Can you hear or see the outdoor unit trying to start?
If thermostat control isn't reaching the outdoor unit, the problem is upstream. If it is, you're looking at outdoor electrical.
Compressor and Motor Circuits
Contactor:
Does the contactor energize when you call for cooling? You should hear a loud click when the thermostat calls.
Does it stay closed? It should hum slightly with full power. If it chatter (rapidly clicking), voltage is too low or the coil is bad.
Check the coil voltage with the unit running—should be within 10% of rated (usually 24V).
Look for burn marks on contacts. Heavy pitting or discoloration means the contactor is failing and should be replaced.
Capacitor:
Disconnect power immediately. Capacitors store charge and can shock you even with the system off.
Discharge the capacitor with an insulated screwdriver across the terminals (touch both terminals simultaneously).
Measure capacitance with a capacitor tester or multimeter (if it has capacitance mode).
Compare to the label rating (usually 40–50 µF for run capacitors)
Values within ±10% are acceptable
Values below 85% of rating or showing 0 µF indicate failure
Look for visual damage — Swollen or vented capacitor, leaking oil, burn marks.
Compressor Windings:
Measure resistance between terminals (disconnect power first).
Herm to Run: typically 5–15Ω (varies by compressor size)
Herm to Common: typically 3–8Ω
Run to Common: the difference between the other two
Open circuit (infinite resistance): motor winding is open, compressor is dead
Shorted to ground: resistance from any terminal to the case should be infinite (use a megohmmeter for this test)
Unequal values (one winding significantly lower) suggests internal damage
Measure voltage across terminals while running at full load.
Voltage imbalance over 5% suggests problem upstream (power supply, wiring, starting capacitor)
Voltage imbalance under 5% is normal
Starting Capacitor (if equipped):
Same discharge and testing procedure as run capacitor
Starting capacitors fail frequently and cause hard-starting or failure-to-start
Often overlooked; check it on every electrical problem
Amperage Draw
Measure running amperage on all three legs (if 3-phase, which is rare in residential) or both legs (single-phase).
Compare to nameplate rating on the compressor
Running amps should be 85–110% of nameplate, steady state
Amps rising over time indicate motor winding problem or locked compressor
Amps lower than expected suggest voltage issues, low refrigerant charge, or system load reduction (outdoor temp drop, indoor thermostat satisfied)
High amperage draw (over 110% nameplate):
Check voltage—low voltage forces the motor to draw more amps
Check for scroll compressor issues—liquid slugging, mechanical lock
Verify refrigerant charge and system pressure—overcharge increases discharge pressure and head pressure, increasing motor load
Part 3: Refrigerant System Diagnostics
If electrical is fine and the system is running, refrigerant diagnostics are next.
Pressure Readings and Initial Assessment
Take pressure readings after 5 minutes of full-load operation (compressor running, outdoor fan running, high demand conditions).
Know your refrigerant type. Diagnose varies by refrigerant:
R-22 (phased out, older systems)
R-410A (common in systems built 2010–2022)
R-454B (newest, increasingly common)
Baseline pressures vary by outdoor temp and refrigerant type. The following are rough guidelines; always cross-reference with pressure-temperature charts:
Outdoor TempR-410A SuctionR-410A DischargeR-454B SuctionR-454B Discharge95°F100–120 psi350–380 psi90–110 psi330–360 psi85°F85–100 psi300–330 psi75–90 psi280–310 psi75°F70–85 psi260–290 psi60–75 psi240–270 psi
These are approximations. Exact pressures depend on indoor conditions, airflow, load, and system design. Your pressure-temperature chart is the truth; the table above is a sanity check.
Superheat and Subcooling Diagnostics
Superheat tells you the refrigerant condition at the compressor inlet. It's the difference between the actual temperature of the suction line and the saturated temperature at the measured suction pressure.
Procedure:
Measure suction pressure at the compressor inlet service port
Use a pressure-temperature chart to find the saturated temperature at that pressure
Measure the actual suction line temperature with a clamp-on thermometer (not the gauge; that reads static pressure)
Superheat = Actual temp − Saturated temp at suction pressure
Target superheat: 10–15°F for most residential systems (varies by system design—check the equipment spec sheet)
High superheat (>20°F):
Low refrigerant charge (most common)
Underfeeding TXV (less common)
Suction-line restrictions (rare—would show high compressor amperage, low capacity)
Diagnosis: Check subcooling to confirm low charge
Low superheat (<5°F):
High refrigerant charge (overcharge)
TXV overfeeding
Flooded compressor risk—oil dilution, slugging, bearing wear
Action: This is bad. You need to remove refrigerant.
Subcooling tells you the refrigerant condition at the condenser outlet. It's the difference between the saturated temperature at measured discharge pressure and the actual liquid-line temperature.
Procedure:
Measure discharge pressure at the condenser outlet service port (or high side)
Use a pressure-temperature chart to find the saturated temperature at that pressure
Measure the actual liquid line temperature with a clamp-on thermometer (measure below the condenser, away from sunlight)
Subcooling = Saturated temp at discharge pressure − Actual liquid line temp
Target subcooling: 10–15°F for most systems (check spec sheet)
High subcooling (>20°F):
High refrigerant charge (overcharge)
Condenser airflow restricted (dirty condenser, blocked return air, low condenser fan speed)
Diagnosis: Check superheat to confirm overcharge or airflow issue
Low subcooling (<5°F):
Low refrigerant charge
Expansion device underfeeding or restricted
Diagnosis: Check superheat to confirm charge
Charging Procedures
Diagnosis first; charge second. Only charge if you've confirmed charge is the problem through superheat/subcooling.
Low Charge (High Superheat, Low Subcooling):
Identify the leak (if possible) before charging. A system that loses charge will need refilling repeatedly. You have an obligation to find and repair the leak.
Bubble test: Mix a small amount of leak-detection dye with liquid soap, apply to suspect joints while running, watch for bubbles
Electronic leak detector: Reliable for small leaks, especially on valve cores and service ports
UV dye: Inject approved dye into system, run for 15 minutes, inspect under UV light. Best method for finding small leaks.
Calculate charge required (if needed):
Document current condition (pressures, temps, amp draw)
Determine how much charge is needed based on target superheat
Charge incrementally (never more than 0.5 lbs per 5 minutes)
Charging method:
Liquid charging (preferred for large charges): Connect gauges to high-side service port, use a scale, meter liquid refrigerant into the system with a metering valve
Vapor charging: Connect gauges to low-side, meter refrigerant vapor (allow some to boil off from charging cylinder)
Never charge through the compressor inlet while the system is running—you can send liquid into the compressor and damage it
Verify the charge:
Run the system for 10 minutes at full load
Re-measure pressures, superheat, subcooling
Repeat until superheat is 10–15°F
High Charge (Low Superheat, High Subcooling):
Confirm overcharge — Check for flooded compressor symptoms (slugging, knocking, high amp draw, oil carryover)
Remove refrigerant:
Connect recovery machine to both service ports (low and high side)
Run recovery until pressures equalize and approach vacuum
Measure recovered refrigerant by weight
Remove only enough to reach target superheat—usually 0.5–1.5 lbs depending on system size
Verify:
Reconnect gauges
Run system for 10 minutes
Re-measure pressures and superheat/subcooling
Target is 10–15°F superheat
R-454B Specific Considerations
R-454B has a narrower operating window and is more sensitive to charge than R-410A:
Subcooling is critical — Aim for 12–15°F, not lower
Charging must be precise — Over/undercharge symptoms appear faster
Pressure is lower than R-410A at the same outdoor temp (roughly 10% lower)
Vapor charging only for service—never liquid charge through the compressor inlet
Recovery procedures are strict — R-454B requires certification and approved recovery equipment
Compressor Discharge Temperature
High discharge temperature indicates system stress:
Measure discharge line temperature at the outlet of the compressor with a clamp-on thermometer
Normal discharge temp: 130–160°F depending on outdoor temp and load
High discharge temp (>180°F):
High head pressure from overcharge, dirty condenser, or low airflow
High subcooling suggesting overcharge
Inadequate suction line superheat (flooded compressor)
Action: Address underlying cause; high discharge temps shorten compressor life
Part 4: Compressor Diagnostics
If the compressor is running but discharge temp, head pressure, or electrical readings are abnormal, dig deeper.
Compressor Condition Assessment
Listen to the compressor:
Normal: Steady humming during run cycle, slight hum or tick during start-up
Knocking or banging: Mechanical failure, possibly liquid slugging. Stop the unit; this is severe.
Grinding or grinding on start: Bearing wear or internal damage. Unit may be salvageable short-term, but plan replacement.
High-pitched squeal: Bearing wear, especially on older compressors. Document; may need urgent replacement.
Intermittent clicking after shutdown: Normal oil-return clicks as pressure equalizes. Not a problem.
Measure discharge superheat:
Measure discharge line temp at the compressor outlet
Measure discharge pressure
Use pressure-temperature chart to find saturated temp at discharge pressure
Discharge superheat = Actual temp − Saturated temp
Normal discharge superheat: 20–40°F. Higher superheat (>50°F) with normal suction superheat suggests compressor inefficiency or internal gas leakage (worn rings, bad unloader valve if equipped). This compressor is near end-of-life.
Mechanical Lock or Slugging
Mechanical lock: Compressor won't turn—suction and discharge pressure equalize when stopped. This is an instant replacement.
Slugging: Liquid refrigerant enters the compressor cylinder, compressing incompressible liquid. You hear banging or knocking. This can rapidly destroy the compressor.
Immediate action on knocking/slugging:
Turn off the system immediately
Disable the thermostat or switch to OFF
Let the system sit for 30 minutes to allow liquid to drain from the compressor
Check suction pressure—if it's elevated (>25 psi above normal), liquid is trapped
With power off, gently rotate the compressor shaft by hand using a wrench on the crankshaft bolt—this may help liquid drain
Do NOT attempt to start the compressor if you suspect slugging without addressing the root cause
Prevention: Ensure superheat is adequate (10–15°F) and suction line temperature is warm to the touch. Low superheat invites slugging.
Internal vs. External Leaks
Leaking compressor (internal leak):
High suction pressure, low discharge pressure (pressures are close)
High superheat (valve leakage back to suction)
Compressor continues to run but produces little cooling
Low amp draw (low load due to reduced capacity)
Test: With the system running at steady state, close the suction service valve (king valve) for 5 seconds. Watch the pressure gauge:
Suction pressure rises quickly (3–5 psi in 5 seconds): Normal—compressor is compressing
Suction pressure stays flat: Compressor has an internal leak or mechanical failure
External leak (refrigerant loss from piping or fittings):
Manifests as low charge condition
High superheat, low subcooling
System gradually loses capacity over weeks or months
Found by bubble test or electronic leak detector
Part 5: Airflow and Static Pressure Diagnostics
Poor airflow is a common root cause of capacity issues, high discharge temperature, and humidity problems.
Static Pressure Testing
Static pressure is the resistance to airflow in ductwork. Excessive static pressure forces the system to work harder and reduces efficiency.
Equipment needed:
Manometer (water column or electronic)
Access ports in ductwork (you may need to drill them)
Procedure:
Measure return static pressure:
Drill a small hole in the return duct (upstream of the furnace/coil, or in a return plenum)
Connect manometer to the hole with tubing
Run the system on cooling at full capacity
Return pressure should be -0.1" to -0.2" water column (negative, pulling toward the furnace)
Measure supply static pressure:
Drill a hole in the supply duct (downstream of the coil/furnace)
Connect manometer
Supply pressure should be +0.1" to +0.3" water column (positive, pushing away from furnace)
Calculate total external static pressure (ESP):
ESP = |Return pressure| + Supply pressure
Example: -0.15" return + 0.20" supply = 0.35" ESP
Target: ESP should be ≤0.15" for most systems. Anything over 0.25" is high and indicates ductwork restriction.
High Static Pressure (>0.25"):
Dirty filter — Most common cause. Replace immediately.
Undersized ducts — Ductwork too restrictive for the system's airflow. Review Manual D.
Kinked or collapsed ducts — Inspect ductwork for damage.
Blocked returns — Furniture, doors, or vents blocking return air. Clear them.
Dampers restricted — HVAC zone dampers or branch dampers partially closed. Open fully or remove.
Action: Identify and correct the restriction. If ducts are undersized, ductwork modification may be needed. Sealed, insulated ducts improve efficiency and reduce static pressure.
Airflow Measurement
Indirect airflow assessment:
Temperature differential (ΔT): Measure supply air temp and return air temp
ΔT = Return temp − Supply temp
Normal: 14–22°F
Low ΔT (<12°F) suggests high airflow (oversized system, short-cycling) or low capacity
High ΔT (>25°F) suggests low airflow or high capacity demand
Airflow from equipment nameplate:
Most systems have CFM ratings on the air handler or furnace
Cross-check against Manual D ductwork design
Actual CFM in the field may differ due to static pressure and filter condition
Direct airflow measurement (advanced):
Ductboard or plenum hood: Covers the return or supply opening to measure air speed and flow
Anemometer: Measures air velocity at multiple points in the duct, calculates total CFM
These are useful when troubleshooting specific rooms or zoning issues
Coil Airflow Issues
Frozen indoor coil:
Symptom: Supply air is cold initially, then warms or stops as coil ices over. Compressor runs but no cooling after 15–30 minutes.
Cause: Restricted airflow (low superheat + low air velocity = below-freezing coil temp)
Immediate action: Switch system to FAN-ON or HEATING to warm the coil and melt the ice
Root cause: Low charge, dirty filter, blocked returns, or indoor fan failure
Prevention: Maintain adequate superheat (10–15°F) and sufficient return airflow
Dirty condenser:
Visible: Leaves, pollen, dust, or debris blocking condenser fins
Effect: Restricted air over condenser → high head pressure, high discharge temp, reduced capacity, high amp draw
Field cleaning: Use a soft brush or low-pressure water spray to clean fins. Never use high-pressure washer—damages fins.
Prevention: Locate outdoor unit away from trees, shrubs, or sources of debris. Annual cleaning recommended in areas with high pollen or dust.
Part 6: System Performance and Capacity Testing
If refrigerant, electrical, and airflow all check out, but the system still doesn't cool adequately, you're diagnosing a design or load issue.
Load Calculation Assessment
Ask the customer:
"Has this system always struggled on hot days, or is this new?"
"Did the previous owner say anything about AC performance?"
"Has your home been renovated (new windows, insulation added) recently?"
If the system is undersized:
Manual J load calculation reveals actual cooling demand
Compare to system capacity (nameplate BTU)
Most homes need 400–600 BTU/hour per square foot (climate and construction dependent)
If nameplate capacity is 20% below Manual J load, the system is undersized
If the load recently increased:
Poor insulation in the attic (squirrels, settling, removal over time)
Condenser shaded by new trees, reducing efficiency
Large new window or glass door added
Changes in occupancy (more people, more equipment heat)
Fix: Either reduce the load (insulation, window treatments, ventilation) or upgrade the system.
System Capacity at Rating Conditions
Most systems are rated at:
Outdoor temp: 95°F
Indoor temp: 80°F dry bulb, 67°F wet bulb (51% RH)
Superheat: System-specific
If your measured conditions differ significantly, capacity will differ.
Derating for non-rating conditions:
High outdoor temp (>95°F): Capacity decreases ~3–5% per 5°F rise
Low outdoor temp (<95°F): Capacity increases ~3–5% per 5°F drop
High indoor temp (>80°F): Capacity decreases ~2–3% per degree
Poor airflow or high static pressure: Capacity decreases 2–5% per 0.1" ESP above target
Example: 95°F outdoor, 78°F indoor measured. System rated at 95°F/80°F. Expected capacity is roughly 3–4% lower than nameplate.
Part 7: Common Failure Modes and Diagnostics
Not Cooling (No Capacity)
Diagnostic flowchart:
System running? → Yes, proceed. No, go to "Won't Start"
Check superheat and subcooling
High superheat, low subcooling? → Low charge (see charging procedure)
Low superheat, high subcooling? → Overcharge (see charging procedure)
Normal superheat/subcooling? → Proceed
Check discharge pressure and temp
High head pressure, high discharge temp? → Condenser airflow, overcharge, or high outdoor load
Normal pressures but still not cooling? → TXV (Thermostatic Expansion Valve) issue or internal compressor leak
Check supply/return airflow and static pressure
High static pressure? → Dirty filter, blocked returns, or ductwork issue
Low airflow? → Check indoor fan, coil freeze risk
Check for system design issue
Undersized system? → Manual J required
Poor insulation or excessive heat gain? → Envelope improvements needed
Short-Cycling (Compressor Cycles Too Quickly)
Symptoms: System runs 2–5 minutes, then shuts off for 5–10 minutes, repeats. Never reaches setpoint.
Causes:
Oversized system → System cools space so fast it satisfies thermostat before adequate humidity removal
High head pressure cutting off compressor → Overcharge, dirty condenser, high outdoor temp
Low charge triggering low-pressure cutout → If system has LPS protection, low superheat (flooded) triggers cutoff
TXV hunting or oscillating → TXV is overfeeding/underfeeding rapidly
Diagnosis:
Measure pressures during short cycles
If discharge pressure is rising and exceeds cutout threshold (usually 400–430 psi), head pressure is shutting down compressor
If suction pressure is rising above normal, TXV is overfeeding
If system was recently installed, check superheat; if <5°F and compressor is cycling on low-pressure cutout, charge is too high
Fix:
Remove overcharge
Clean condenser
Check TXV adjustment (if accessible)
If system is oversized, that's a design issue (may be acceptable if humidity control is adequate)
High Discharge Temperature and Pressure
Immediate concern: High discharge temperature (>180°F) with high head pressure indicates stress and shortens compressor life.
Root causes:
Overcharge → High subcooling, normal or low superheat
Dirty condenser → Restricted condenser airflow
High outdoor temp → Normal at 95°F+; system is working as designed
Low airflow over condenser → Condenser fan issue or blocked returns forcing the system to recirculate hot air
Flooded compressor → Low superheat, high discharge pressure
Diagnosis:
Measure discharge pressure and temp
Check superheat/subcooling
Inspect condenser for blockage
Measure condenser fan amperage; compare to nameplate
Check for adequate clearance around outdoor unit (at least 2–3 feet on all sides)
Fix:
Remove overcharge if present
Clean condenser
Check condenser fan motor and capacitor
Ensure return air is not recirculating (outdoor unit should pull cooler air, not hot air from other sources)
High Amp Draw
Concern: Compressor amperage >110% of nameplate indicates excessive motor load.
Causes:
Low voltage → Voltage <220V at disconnect forces motor to draw more current for same power
High head pressure → Overcharge, dirty condenser, high outdoor temp
Flooded compressor → Attempting to compress liquid → high motor load
High suction pressure → System starved for refrigerant or compressor valves leaking
Diagnosis:
Measure voltage at outdoor disconnect (should be 235–245V)
Measure suction and discharge pressures
Check amp draw at multiple times during the run cycle (starting, running, steady state)
If amps rise over 5–10 minutes, compressor is heating and winding may be failing
Action:
If voltage is low, check panel and supply wiring
If pressures are abnormal, address refrigerant charge
If amps continue to rise, compressor may be failing—plan replacement
Won't Start (Compressor Not Running)
Diagnostic flowchart:
Check thermostat → Is it calling for cooling? Does the indoor fan start?
No indoor fan, no call for cooling? → Thermostat problem or power to indoor unit
Indoor fan starts, compressor doesn't? → Outdoor unit power or contactor issue
Check disconnect and breaker → Are they ON?
Breaker is OFF or tripped? → Reset; if it trips again, investigate short
Disconnect is OFF? → Turn ON and retry
Check contactor → Does it click when thermostat calls?
No click? → No control signal from thermostat or indoor unit (check wiring and thermostat)
Click but doesn't hold closed? → Contactor coil is failing (measure 24V coil voltage; should be 22–26V)
Held closed but compressor doesn't turn? → Compressor circuit issue
Check capacitor → Measure run capacitor and start capacitor
Capacitor is dead (0 µF or far below rating)? → Replace
Capacitor is good? → Check compressor windings
Check compressor windings → Measure resistance between terminals
Open circuit (infinite resistance)? → Compressor winding is open; compressor is dead
Very low resistance (<1Ω)? → Winding may be shorted; megohmmeter test needed
Normal resistance? → Compressor may be mechanically locked (see mechanical lock section)
Check power to compressor → With contactor closed and system trying to start, measure voltage across compressor terminals
No voltage? → Wiring, contactor, or disconnect issue
Voltage present but compressor doesn't run? → Mechanical lock or internal compressor failure
Humidity Not Being Removed
Symptom: Temperature reaches setpoint but air feels clammy and humidity is high (>60% indoors).
Root causes:
Short-cycling → System cycles off before enough air passes through coil for dehumidification
Oversized system → Same issue—system satisfies temperature before removing moisture
Low airflow → Air moves too fast through coil; insufficient contact time for condensation
High indoor humidity load → Moisture from occupants, showers, cooking, or external infiltration exceeds system's dehumidification capacity
Diagnosis:
Measure superheat/subcooling (normal is fine—humidity issue isn't always a refrigerant problem)
Measure supply/return static pressure (high pressure = low airflow)
Measure ΔT across coil (should be 14–22°F)
Check for air infiltration (leaky windows, open doors)
Measure indoor humidity at thermostat location
Fix:
Reduce system cycling (lower setpoint slightly to keep system running longer)
Increase airflow (reduce static pressure by cleaning filter, clearing returns)
Add supplemental dehumidifier if needed
Seal air leaks if infiltration is high
For persistent issues, recommend system upgrade or add ERV/ERH (Energy Recovery Ventilation/Heating)
Part 8: Seasonal and Coastal Considerations
Salt Air Corrosion (Southwest Florida)
Inspection priorities:
Visual corrosion check on condenser cabinet, fins, connections
Electrical connection inspection — Check terminal blocks, capacitor terminals, contactor contacts for green oxidation
Refrigerant line corrosion — Copper lines should be shiny; green oxidation indicates salt exposure
Fastener corrosion — Bolts and brackets should be stainless steel or painted; rusted fasteners corrode quickly
Maintenance during service:
Clean corroded electrical connections with contact cleaner or wire brush
Recommend protective coatings or stainless steel upgrades if corrosion is heavy
Schedule seasonal maintenance (spring and fall) for customers in salt-air zones
Post-storm inspection after hurricanes or high-wind events
Summer Peak Load Conditions
When it's 95–100°F outside:
System performance is at or below nameplate capacity
Discharge pressure and temperature are high (expect 350–400 psi, 140–170°F)
Amp draw is high (expect 90–105% of nameplate)
System may struggle to cool if there's any capacity loss (low charge, dirty condenser, airflow issues)
During peak load diagnostics:
Be conservative with charge adjustments (add small amounts)
High head pressure is normal; focus on superheat to determine charge
If customer complains of inadequate cooling at peak load, a Manual J and capacity assessment is warranted
Document the condition (outdoor temp, indoor temp, pressures, amp draw) so you can compare to future calls
Part 9: Safety Considerations
Electrical Safety
Always assume a capacitor is charged. Discharge before touching terminals.
Use a non-contact voltage tester before working on electrical circuits.
Never work on live circuits unless absolutely necessary. Disconnect power when possible.
Verify disconnects are working (open and close contactor by hand to confirm).
Refrigerant Handling
Only use EPA-certified recovery equipment and procedures.
Vent no refrigerant to atmosphere.
Use appropriate safety equipment (gloves, goggles, closed-toe shoes).
R-454B is mildly flammable (A2L). Use caution with open flames or heat sources.
Be familiar with properties of each refrigerant you work with.
System Pressure
Relief valves and rupture discs protect against overpressure. Never block them.
High-pressure systems can rupture if overfilled. Always verify charge with superheat/subcooling, not just pressure.
Never pressurize a system above rated working pressure.
Personal Protection
Discharge clamps on suction and discharge lines before disconnecting to avoid refrigerant exposure.
Wear appropriate PPE (gloves, goggles, long sleeves) when handling refrigerant.
Use a recovery machine with proper ventilation.
