Laundry Equipment Repair: Dryers

Improperly vented dryers can pose a serious fire hazard. This hazard can be drastically mitigated or even eliminated by installing a fire-safe venting system.

Dryers are probably the simplest appliance you'll ever work on. Dryer technology doesn't change. All dryers are basically a drum, a belt, a motor and heat source. Throw in a few switches and bells, package it in flimsy sheet metal with very sharp edges and you've got a dryer. For these reasons, unless you're going from gas to electric or vice-versa, it almost never makes sense to buy a new dryer.

Most dryers, gas or electric, contain three different types of thermostats: 1) the cycling thermostat which cycles on and off to maintain 125 to 165F in the drum, 2) the hi-limit thermostat which temporarily cuts off the heating element in case of an overheat condition usually above 175F, 3) and a non-resettable thermal fuse which, depending on the type of fuse, either permanently cuts off the heating element or shuts down the entire dryer.

No Tumble

Broken belt. Open dryer and see if belt is still wrapped around the drum. Pull on the belt to make sure it's not just hanging there. Inspect belt condition. On models with a flat belt (White-Westinghouse), the belt can sometimes wear thin to the point that it not longer exerts enough friction on a loaded drum to turn it. Do not apply spray adhesive in this case: replace the belt. If belt is broken, look for contributing causes for failure such as worn drum rollers, damaged felt kit, or stiff idler roller.
Motor burned out. Remove belt from motor pulley and start dryer. If motor runs but is noisy and motor is unable to turn the drum when the drum belt is threaded back on the motor pulley, then replace the motor.
Thermal fuse is open. Run continuity test.
Noisy

Worn rear drum rollers, idler pulley, or drum front slide kit. Whirlpool/Kenmore problems will usually be in the rear drum rollers or idler pulley, Maytag problems will usually be the front slide kit. GE/Hotpoint problems will usually be the front slide kit or rear drum center bearing.
Worn blower wheel (Maytag and Magic Chef). Test by rotating blower wheel back and forth rapidly by hand. If a lot of play is noted, replace the blower wheel. Noise originating from the blower wheel is indicated by being most noticeable when first starting the dryer and then when the stopping it.
Idler pulley bearing burned out. Characterized by a high-pitched squealing noise.
Clothes Take Too Long to Dry

Dryer vent is too long, kinked/restricted, or full of lint. Dryer vent should be constructed of UL-approved materials--white vinyl is a big no-no because it is flammable. Check dryer exhaust force at outlet hood. The exhaust should exert strong pressure against your hand. If no stronger than a breath, replace the vent system. For best results, vent length should not exceed 12 feet.
Dryer lint screen is clogged with lint or finely pulverized detergent residue (in this case, also check the cold water valve at the washer--clothes are not getting rinsed).
Operating thermostats out of tolerance.
Dryer Doesn't Run At All

Broken door switch. Check continuity in the open and closed position.
No power at outlet. Measure for 120v (gas dryers), and 240v L1 to L2 plus 120v L1 or L2 to neutral in an electric dryer outlet.
Electric Dryers
No Heat

One leg of the 240 volts AC at the dryer outlet is missing. Motor may still run (L1 to N) but heater needs 240 volts AC (L1 to L2). Circuit breaker is a two-pole, 30 amp breaker. Try resetting. If heat is restored, replace breaker because it will trip again.
Open heating element. Run ohms check. Should read 12 to 35 ohms.
One of the thermostats is open. Run continuity check.
Bad timer contact in heater circuit. Trace timer circuitry--may be possible to run external jumper and restore circuit to heater.
Bad temperature selector switch, run continuity check.
Gas Dryers
No Heat

Defective ignitor. Suspected when ignitor fails to glow at all. Confirm by testing for 120v at the ignitor terminals. If present, ignitor is bad. Otherwise, suspect the flame sensor.
Failed gas valve or holding valve coil. Run ohms check on each valve. May also need to actuate each valve with a test cord since that may only fail after being actuated a couple of times.
One of the thermostats are open. Run continuity check.
Bad flame sensor. If flame fails to ignite at all and the ignitor does is not getting 120v, suspect the flame sensor.