Same-Day Furnace Repair — Kearns, UT Case Study

A Kearns customer called us at 8:15 AM on a December morning after their furnace had been short-cycling overnight and finally stopped producing heat entirely. Outdoor temperature was 22°F, indoor temperature had dropped to 62°F by the morning call, and the customer needed reliable heat restored before the next night’s predicted overnight low of 18°F. The 16-year-old furnace had been showing intermittent ignition issues for several weeks but had been operating sufficiently until this complete failure.

This case study documents a typical same-day furnace repair call with the diagnostic process that identified multiple related component failures, the same-visit repair, and the customer follow-up.

Customer Situation

• Home: 1995-built Kearns single-story, approximately 1,580 sq ft
• Existing equipment: 16-year-old 80% AFUE Goodman furnace (mid-life replacement of original 1960s atmospheric-vent unit)
• Symptom: Short-cycling for several weeks; complete ignition failure overnight; no heat by morning
• Severity: Cold but not severe (22°F outdoor, 62°F indoor); no immediate emergency but customer needed prompt repair before evening cold
• Time of call: 8:15 AM weekday morning
• Maintenance plan status: Not currently enrolled

Scheduling

• Initial call received and triaged at 8:15 AM
• Identified as same-day appointment (not after-hours emergency)
• Technician scheduled for 1:30 PM arrival window
• Customer informed of estimated arrival window and diagnostic visit fee ($99–$199 applied toward repair)

On-Site Diagnostic

Arrival: 1:25 PM (slightly early)

Technician: Mike Reyes (lead service tech)

Initial observations:
– Furnace not igniting on thermostat call
– Inducer motor starting and pressure switch closing properly
– HSI (hot surface igniter) energizing but appearing dim/orange rather than bright orange/yellow
– Gas valve opening on cue but flame not establishing reliably
– After establishing flame on one of multiple attempts, flame sensor not detecting flame reliably

Diagnostic measurements:

• 24V at thermostat call: ✓
• Inducer motor amp draw: 0.85 amps (nameplate 1.2 amps) ✓
• Pressure switch closing: ✓
• HSI resistance: 132 ohms (manufacturer spec 40–80 ohms — well outside acceptable range, HSI degraded)
• Gas valve operation: ✓
• Manifold gas pressure: 3.4″ wc (altitude-corrected target 3.5″ wc) ✓
• Flame sensor microamps: 1.2 µA (manufacturer spec 4–10 µA after cleaning — fouled or degraded sensor)
• Static pressure: 0.45″ wc ✓
• Heat exchanger borescope inspection: minor surface deposits but no cracks visible

Diagnosis:

Two component failures:
1. HSI failure — resistance well above acceptable range; producing inadequate ignition heat causing unreliable flame establishment
2. Flame sensor failure — microamp reading well below acceptable range; not detecting flame even when established, causing safety shutoff

Either component alone would produce the short-cycling and ignition issues. Both failing together created the complete ignition failure overnight.

Customer Conversation

Diagnostic complete at 2:10 PM. Discussed findings with customer:

• Both HSI and flame sensor have failed
• Service truck carries replacement parts for this Goodman model
• Repair cost: $625 (parts $310, labor $275, plus diagnostic fee $99 = total $684)
• Equipment otherwise in serviceable condition; no other concerns
• Heat exchanger sound; combustion analysis to be completed after repair

Customer approved repair.

Repair-vs-replace discussion:
– Equipment is 16 years old, approaching end of typical service life
– Today’s repair extends operational life but doesn’t address overall equipment age
– Realistic outlook: equipment can likely continue for 3–6 more years with periodic component replacements; major failure (gas valve, blower motor, control board) within next few years is possible
– Customer can plan replacement during summer for non-emergency installation, or continue running until major failure occurs
– Maintenance plan would catch developing issues earlier and reduce emergency cost

Customer chose repair today plus maintenance plan enrollment.

Repair

Repair duration: 2:10 PM to 2:55 PM (45 minutes)

Work performed:

1. Power isolation — service disconnect off, capacitor discharged for safety
2. HSI replacement — old igniter removed, new OEM Goodman HSI installed with proper mounting and wiring
3. Flame sensor replacement — old sensor removed and cleaned (showed heavy oxidation), new sensor installed
4. Burner inspection — burner ports verified clean during HSI access
5. Manifold pressure verification after restart
6. Combustion analysis after restart:
   – CO: 18 ppm air-free ✓ (target <50)
   – O2: 7.6% ✓
   – Combustion efficiency: 81.2% (consistent with 80% AFUE equipment) ✓
   – Draft pressure: -0.05″ wc ✓
7. Temperature rise verification: 48°F (target 35–65°F) ✓
8. New flame sensor microamps after operation: 6.8 µA ✓
9. HSI resistance after installation: 58 ohms ✓
10. Multiple full firing cycles verified for stable operation
11. Indoor CO measurement: 0 ppm ✓

Customer Outcome

Equipment restored: 2:55 PM, approximately 6.5 hours from initial morning call

Home temperature recovery: Customer reported indoor temperature reached 70°F by 5:30 PM, well before evening cold

Final invoice:
– Diagnostic visit: $99 (applied toward repair)
– HSI replacement: $310
– Flame sensor replacement: $185 (combined with HSI service)
– Labor (45 minutes): $130
– Total: $625

Maintenance plan enrollment:
– Annual fee: $189
– Includes: 2 tune-ups per year (furnace fall, AC spring), waived diagnostic fees on emergency calls, 10–15% parts and repair labor discount, priority scheduling
– Diagnostic visit fee waived as enrollment benefit applied retroactively to current call (saved customer $99)
– Customer’s effective net cost: $526 for repair + $189 maintenance plan = $715 total

Follow-Up Visit (Fall Tune-Up, 9 Months Later)

Fall maintenance plan tune-up scheduled. Visit included:

• Full combustion analysis (CO 16 ppm, efficiency 80.8%, all within spec)
• Cleaning burners and inducer
• Inspecting heat exchanger with borescope (still sound)
• Verifying all safety controls
• Checking ductwork for any developing seam issues
• Replacing air filter
• Customer signed up for SMS reminder service for monthly filter changes

No additional service needed. Equipment continued reliable operation through winter.

What This Case Study Demonstrates

• Multiple failures from related root cause — HSI degradation often produces flame sensor fouling because incomplete combustion deposits accumulate; diagnostics identified both rather than fixing one and missing the other
• Same-day service for non-emergency repairs — morning call → afternoon service → evening comfort restored, all within standard business hours pricing
• Honest equipment age conversation — discussed realistic outlook on continued operation vs. replacement planning rather than pushing premature replacement
• Maintenance plan value demonstrated — first-visit enrollment saved customer $99 in diagnostic fees plus future repair discounts; tune-up 9 months later caught any developing issues before they became emergencies
• Diagnostic measurements documented — HSI resistance, flame sensor microamps, combustion analysis all show why diagnosis was correct and verify repair quality
• Heat exchanger inspection included — borescope verification on 16-year-old equipment confirmed sound condition rather than recommending replacement based on age alone

Need Same-Day Furnace Repair?

If you have a furnace issue in Kearns, call us at (385) 250-0687. Same-day service typical for non-emergency repairs during business hours; emergency response 24/7 for urgent situations.

• Phone: (385) 250-0687
• Address: 4454 Manhattan Ct, West Valley City, UT 84120

See Furnace Repair in Kearns →