Dryer Service Reference
Why this matters
Dryer failure stops the laundry; vent blockage causes thousands of house fires annually. The appliance tech who can diagnose dryer issues + service vents safely delivers safety + customer satisfaction. This is the field card.
Dryer types
Electric (240V): most common new install; 5,000 - 6,000W heating element; 30A circuit.
Gas (natural OR propane): more efficient operation; gas line + 120V electric.
Heat pump dryer: ductless; uses refrigeration cycle; uses 50% less energy; longer cycle time.
Vented (most common): pulls air through drum; exhausts to outside.
Ventless / condensing: condenses moisture in unit; no external vent.
Top-load / front-load: typically front-load for stacked washer/dryer pairs.
Heating element types
Electric: nichrome wire coil; 5,000W typical. Replaces as single unit.
Gas burner: pilot OR electronic ignition; flame heats drum.
Heat pump: refrigerant evaporator absorbs ambient heat.
Common dryer problems
Won't start: door switch fail; start button + control board; thermal fuse blown; no power (breaker); belt broken (some require restart).
No heat (electric): heating element fail; thermal fuse blown; high-limit thermostat; burned terminal block; 240V supply (one leg dead = no heat).
No heat (gas): gas supply (valve closed); igniter failed; flame sensor; gas valve solenoid; thermostat.
Long cycle / damp clothes: clogged vent (most common); heating element partial fail; thermostat issue; lint buildup.
Squealing/scraping: worn idler pulley; drum bearing; rollers; frayed belt.
Drum not turning: belt broken/loose; motor failure; tension idler.
Burning smell: lint near heater; motor windings; belt rubbing.
Overheating shutdown: vent clogged (most common); high-limit tripped; blower wheel jammed.
Vent system (CRITICAL safety)
Dryer vents cause thousands of fires annually. Maintenance: lint trap every load; vent hose annually; full vent annually. Tools: vacuum, vent brush (rotary OR straight), cleaning rod, compressed air. Signs of clog: long dry time, hot exterior, lint on clothes, burning smell, high energy use. Vent type: rigid metal 4" smooth (preferred); foil flex (max 6 ft transition per IRC); plastic flex (NOT code; replace). Length max 35 ft total equivalent per IRC. Termination: louvered cap on exterior wall OR roof; NEVER attic/crawl.
Common service procedures
Vent cleaning. Heating element. Door switch. Thermal fuse. Drum belt. Drum bearing/roller. Motor. Control board. Gas igniter. Gas valve.
Diagnostic procedure
Step 1 - Verify the complaint (long dry time vs no heat are different paths).
Step 2 - Power check:
- 240V at outlet (electric); 120V at outlet (gas)
- Breaker NOT tripped
- Both legs of 240V present
Step 3 - Open access panels (back OR front; OEM-specific).
Step 4 - Test components:
- Multimeter for continuity:
- Heating element: 8 - 15 Ω typical electric
- Thermal fuse: continuous = good; open = blown
- High-limit thermostat: continuous = good
- Door switch: closed when pressed
- Motor windings: per OEM
Step 5 - Mechanical inspection:
- Belt condition + tension
- Idler pulley wobble
- Drum bearing free spin
- Rollers + glides
Lint trap location + cleaning
Front-load dryers (typical): lint screen at door OR top edge.
Top-load (older): at door OR control panel.
Cleaning: each load minimum.
Lint trap housing: pull out + clean with brush every 6 - 12 months.
Vent cleaning service (recommended annually)
Tools + procedure:
- Disconnect dryer from outlet OR gas
- Slide dryer out from wall
- Disconnect vent hose at dryer
- Insert vent brush + rotate through full vent
- Clean from outside termination (cap) inward
- Vacuum vent + dryer rear
- Reconnect; check for leaks at flex connections
- Test cycle + verify exhaust at termination
Common dryer mistakes
Skipping vent maintenance (fire risk). Using plastic flex vent (banned by code; fire risk). Long vent run (> 35 ft equivalent; reduces drying performance). Multiple sharp bends. Termination indoor (attic OR crawl); causes mold + structural rot. Damp lint buildup near heater.
Gas dryer specifics
Gas line: 1/2" gas line with shutoff valve.
Pressure: typical 7" WC natural gas; 11" WC propane.
Igniter (silicon carbide): glows to ignite gas; typical 100 - 400 Ω cold resistance.
Flame sensor: rod OR microswitch; senses flame is lit.
Gas valve solenoid: opens gas flow when energized.
Combustion air: required ventilation around appliance.
Vent: same as electric; 4" rigid metal duct.
Heat pump dryer
Closed-loop refrigerant system: condenses moisture from drum air.
No vent required: water collected in pump-out tank OR drained.
Slower cycle time: 1.5 - 2x electric vs gas dryer.
Lower energy use: 50% less than standard.
Maintenance: drain water tank OR plumb drain; clean filter regularly.
When to replace
Repair > 50% of new unit: replace.
10+ years old + major repair: consider replace.
ENERGY STAR upgrade: efficiency justifies replace if old.
Heat pump consideration: for energy-conscious customer.
Customer education
Vent cleaning annually: explain fire risk.
Don't dry: very large bulky items (suffocates flow); rubber-backed rugs (heat damage).
Loose lint = fire: keep area around dryer clean.
Door seal check: visual inspection.
Listen for new noises: early warning of bearing failure.
Truck stock
Common heating elements (universal + brand-specific), thermal fuses (multiple), high-limit thermostats, door switches, drum belts (multiple sizes), drum rollers + glides, idler pulleys, dryer vent brushes + rods, multimeter, gas leak detector (gas dryer), vent cleaning vacuum, flexible scope (camera for vent inspection).
Safety reminders
Gas dryer: shut off gas before service.
Electric dryer: 240V; verify dead before working internal.
Vent fire risk: never operate dryer without lint trap.
Plastic flex vent: replace immediately; fire risk.
Heating element handling: hot after operation; allow cooling.
NEVER skip dryer vent maintenance. Tens of thousands of dryer-related fires per year + most from lint accumulation. Annual vent inspection + cleaning is the single most-impactful service for customer safety. When a customer complains "clothes take forever to dry", check the vent first - 80% of the time the vent is restricted + the heating element is fine. Selling the annual vent cleaning service prevents the fire + saves the dryer + delivers ongoing relationship.
References
- IRC M1502 (dryer venting)
- NFPA dryer fire statistics
- Manufacturer technical data (Whirlpool, GE, LG, Samsung, Maytag)
- Manuall internal: Exhaust + Ventilation, Common Codes Overview