2 speed vent fan now only works at high speed

An old elecricians joke says "do you know why it hums? It dosn't know the words" Al kidding aside ,have you checked to see how free the fan blade is? The should spin very freely. It kind of sounds to me like it may be having a hard time comming up to full speed. You may try some graphite lube on the motor. If I recall Broan has a lifetime garrentee on the motor. You might just want to repace it if I am correct.

Agreed! It totally works. Our fan and lights were stuck on high. Flipped the hood circuit breaker off for 30 seconds then back on again and all controls are working normally again. Thanks!

In central HVAC systems, the fan motors will sometimes have a dual motor speed. You may need the higher setting. If you are already at the higher setting, you may need a diverter in the system or bigger unit (more tonnage).

All cars are designed with a blower fan motor that pushes air through the ventilation system. This air is processed by a series of vents to direct the air to various positions. Example: heater, air conditioner and defrost modes. Most blower motors are power by a basic electrical circuit that utilizes a multi resistor or a solid-state resistor to control different fan speed modes (low, medium low, medium and high). If the resistor malfunctions it may lose one or more of the lower fan speed settings.
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I'm not familiar with your particular car, but this info may be of some help to you...

Dual fan cars work in a few ways:
1) Some only use one fan during normal cooling, and turn on the second either when the temperature reaches a certain level, and/or when the air conditioning is running.
2) Some use both fans for normal cooling, but at least one of the fans have a dual-speed motor. Generally only one has dual-speed motor, which operates at low speed during normal cooling cycles, and operates at high speed at a predetermined temperature, and/or when the air conditioning is running.

Based on this, it's possible that your system is working correctly, or you have the chance that your low speed portion of the cooling system is not functioning. Check the wires going to the fans. If there are only two wires, then it's a single speed fan. If there are three wires, it's a dual speed fan.

Based on that information, you should be able to determine if your system is working correctly or not.

2 airflow sensor out of operating range 3 coolant temp sensor out of operating range 4 oxy sensor indicates full rich 5 throttle potentiometer/airflow sensor... (low throttle pot signal with high airflow sensor signal) 6 throttle pot/airflow sensor...... (high throttle pot signal with low airflow sensor signal) 7 throttle pot...idle fuel adjustment failure(idle speed??) 8 intake air temp sensor...open or shorted circuit to sensor 11 Throttle pot at idle: Throttle pot idle trim out of normal range 12 Airflow meter: MAF signal out of range 14 Coolant thermistor: Resistance out of range or static during engine warm up 16 Air thermistor: Resistance out of range 17 Throttle pot: Out of range 18 Throttle pot/Airflow: Low throttle pot signal at high airflow 19 Throttle pot/Airflow: High throttle pot signal at low airflow 22 Fuel pump drive: ECU output to fuel pump relay 23 Fuel supply: Engine running too rich 24 Ignition Drive: ECU output to ignition Amp 26 Air leak: Engine running too lean 29 ECU self check 33 Injector Drive: ECU output to injectors 34 Injector: Looks for Injector dribble 37 EGR Drive: ECU output to EGR switching valve 39 EGR check sensor: EGR not working (normally pipe blocked) 44 Lambda (O2) sensor: Poor mixture control rich or weak (or misfire) 46 Idle speed Control valve: ECU output to Coil AB 47 Idle speed Control valve: ECU output to Coil CD 48 Idle Speed Control Valve: Stepper motor grossly out of position 66 Air pump: ECU output to air pump relay 68 Road speed sensor: Seen speed < 5km/h at high engine airflow 69 Drive/Neutral switch: Seen cranking in "D" or high airflow in "N" 89 Purge Valve drive: ECU output to purge valve
this is all I could find

Assuming that the dealer is correct and isolated the problem down to the blow motor...
it IS possible for the motor to work intermittently due to heat buildup. Malfunctions due to heat will call the motor to run fine for a bit, and then quit when the motor reaches a high enough temperature to cause a malfunction. It would then quit working until it cooled back down, and repeat the process.

Whether is it just dead, or it is intermittently dead, for all intensive purposes, the motor is no longer usable and needs to be replaced with a new unit.

The indoor blower motor is sometimes a 3 speed motor.The heat usually works on low or medium speed.But the a/c is usually on high speed,this gives greater air flow across the evaporator coil to give you better cooling,also better air flow at ducts.These speeds are usually wired through a relay in the inside unit (air handler).They can be changed.If you go to thermostat and put the fan switch to "on" the blower should operate on "high" speed.With the fan switch set to "auto"the operation will determine the fan speed.Hope this helps. Gregg

Concerning your broken vent -- this can be caused by a broken linkage or a malfunctioning servo motor as well. these vent have air ducts the sway back and forth to adjust the dual air flow function. if the servo o linkages are malfunctioning or not connected for some reason, it will not allow total control of the air flow and temperature range. Now, if you have a combination of a flow error and temperature error as well, thai can be caused by a combination of the two.

In this case, you will need to inspect the linkages as well as the servo motor function as well. in addition, i would test the air temp sensors for there operational value. they control the temp when you adjust the coll or hot function.

Concerning the Loud noise coming from the blower fan---

This issue can be caused by a misalignment within the blower housing or, it can also be caused by some minor damage within the motor itself, causing it to rotate in a erratic manner, in return, forcing it to rub against the housing itself. the best solution here is to extract this blower fan housing and inspect for lose fan propeller and motor stability. replace parts accordingly.

PLease rate and have a great day:)

I finally got my oven to work properly by shutting off the breaker and resetting the main clock. Cured the always locked problem as well as the beep twice when self cleaning.

Have to repeat this every few months since the problem seems to come back.