TECNO Exhaust Hood Fan Motor

[carlyai]

I have a Tecno exhaust fan hood over the gas cooker in the Isaan kitchen.  This unit gets used a great deal.

So wifey said it wasn't working, which wasn't (fan not spinning and just humming). So we pulled it out, set it up on the bench, and it worked OK. Seemed a bit shy on oommfff but still worked. So stuck it back in the kitchen, turned it on and off and all OK. 

Couple of days later, the same problem, fan not working just humming. Took it out, oriented it the same way on the bench as in the kitchen and it worked all day, and again the next day. Re-installed it and it stopped working again after a few days.

Took it out again, it worked again on the bench but thought I'd get the motor changed. Alas no one wants to change it in Mukdahan.

Question Time.

1. The motor is capacity start, am I correct in thinking the motor wouldn't start if the capacitor was faulty? 

2. Could the capacitor cause the motor to be lacking in power once it is running?

3. If the motor was faulty then it shouldn't run, unless it has some short circuited windings then runs without much ooommmffff?

4. I think the problem is the motor and when the unit or extraction fan hood is all assembled in place, there are filters on the fan inlet and plastice doors that have to open on the fan output and I don't think the fan runs strong enough to create the wind required. Could this be correct?

 

Previously I haven't had success getting spares from HomePro purchased. (Like the thermocouple on the gas hob).

I haven't had a real good look at Tecno web site for parts, but I feel these exhaust fan motors should be fairly easy to come by.

If no one can give me a reason not to change the fan and capacitor, that's what I will do....hopefully.

 

[bankruatsteve]

Easy enough to test or just replace the capacitor.  But, it's likely that it has just got dirty from the grease vapor causing stiction.  Can try cleaning but some motors not easy to do that.

[Crossy]

It's capacitor run. Replace the cap, they're cheap and easy.

 

The motor will lack oomph as the capacitor loses value.

 

Clean things out too whilst it's apart.

[Metropolitian]

Is the issue happening when you start the exhaust fan on highest setting?

Only when starting with 1 or 2, the lowest suction?

 

An historic reason old ventilators with slider switch start with high and then low, is that motors starting better on the highest setting and once they are spinning fine the user can choose a lower speed.

 

Try to replace the capacitor, an comment other members already said and I agree with.

 

Another thing, there can be something wrong with the ball bearings, which explains that it will work once it sits on the bench. The gravitational force (Z) on the axis is different positioned.

Check the spinning of the motor (not connected to the electic) by hand, is there difference when you hold the motor the other way?

[Metropolitian]

2 hours ago, carlyai said:

Question Time.

1. The motor is capacity start, am I correct in thinking the motor wouldn't start if the capacitor was faulty? 

2. Could the capacitor cause the motor to be lacking in power once it is running?

3. If the motor was faulty then it shouldn't run, unless it has some short circuited windings then runs without much ooommmffff?

4. I think the problem is the motor and when the unit or extraction fan hood is all assembled in place, there are filters on the fan inlet and plastice doors that have to open on the fan output and I don't think the fan runs strong enough to create the wind required. Could this be correct?

Answers time ????

 

1. Yes and no, the question should be 'capacity run' ;   On AC, single phase motors need a capacitor and bigger motors need an extra capacitor for starting with bigger torque.

Called run- and starting- capacitor.  The exhaust fan, in your case, only use an run-capacitor

 

2. Once it runs, the starting capacitor should be disconnected (automatic) and only the run capacitor is kept connected.

 

3. If the run capacitor fails, even good ones but with wrong values, the secondary winding isn't energized according the speed and momentary which will make the motor loose 'oomph'.

It's like an combustible engine, when the spark is timed wrong and instead of trying to burn the compressed fuel mixture on the right moment but say 75 degrees off, the engine can stall or sputter and there will be no pulling force. Timing is important to 'spark' eg. energize-secondary-winding and that's what the capacitor do for you.

 

5. The plastic doors should be easy opened with a low air pressure, but closed when there is no airflow so that critters won't be able to go in from outside. The spring has to have that enough force to lift the plastic, and nothing more.

[carlyai]

12 hours ago, Metropolitian said:

Is the issue happening when you start the exhaust fan on highest setting?

Only when starting with 1 or 2, the lowest suction?

 

An historic reason old ventilators with slider switch start with high and then low, is that motors starting better on the highest setting and once they are spinning fine the user can choose a lower speed.

 

Try to replace the capacitor, an comment other members already said and I agree with.

 

Another thing, there can be something wrong with the ball bearings, which explains that it will work once it sits on the bench. The gravitational force (Z) on the axis is different positioned.

Check the spinning of the motor (not connected to the electic) by hand, is there difference when you hold the motor the other way?

I did think of the bearings but seem ok on first inspection and unit runs OK on the bench in the same orientation. 

[carlyai]

Thanks Metropolitan. I forgot my capacitor/motor theory. I thought 2 capacitors for start/run and one capacitor for start. Not one capacitor for run. So thinking capacitor needed for start only. Have to brush up. 

[carlyai]

Thanks Metropolitan. I forgot my capacitor/motor theory. I thought 2 capacitors for start/run and one capacitor for start. Not one capacitor for run. So thinking capacitor needed for start only. Have to brush up. 

... later

Went to the nearest big village to my local dodgy bros. Tv repair shop and he had a capacitor test meter. Checked and no good. He also had another 6uf capacitor. Amazing these tv/electronic corner repair shops. No circuits but fix large tv's and anything. Fixed my computer monitor long time gone. So now good clean, assemble, test run and install and the Isaan kitchen is good to go again. ????

[Yellowtail]

How do you know the fan is not running? 

 

If the plastic doors (backdraft damper) are greasy such that they stick shut, you would get no airflow. Most fans are not sized to overcome a sticking backdraft damper even if it swings freely once it's unstuck. 

 

Likewise, if the filters are clogged with grease, the fan will not move much air. Also. if the motor is warn out, it may be due to either or both of the above, and replacing the motor might be a temporary fix. 

[carlyai]

17 hours ago, carlyai said:

Thanks Metropolitan. I forgot my capacitor/motor theory. I thought 2 capacitors for start/run and one capacitor for start. Not one capacitor for run. So thinking capacitor needed for start only. Have to brush up. 

... later

Went to the nearest big village to my local dodgy bros. Tv repair shop and he had a capacitor test meter. Checked and no good. He also had another 6uf capacitor. Amazing these tv/electronic corner repair shops. No circuits but fix large tv's and anything. Fixed my computer monitor long time gone. So now good clean, assemble, test run and install and the Isaan kitchen is good to go again. ????

The difference in the motor torque is like chalk and cheese. ????

[carlyai]

13 hours ago, Yellowtail said:

How do you know the fan is not running? 

 

If the plastic doors (backdraft damper) are greasy such that they stick shut, you would get no airflow. Most fans are not sized to overcome a sticking backdraft damper even if it swings freely once it's unstuck. 

 

Likewise, if the filters are clogged with grease, the fan will not move much air. Also. if the motor is warn out, it may be due to either or both of the above, and replacing the motor might be a temporary fix. 

Good thoughts but wifey is a greasless cook. I cleaned the unit and not much grease.