• ** REMEMBER! **The microwave can still shock you even unplugged!!

    ALWAYS discharge the high-voltage capacitor first if you even think your hands will come close to any HIGH VOLTAGE components.

    Jeff mentions this: Anything in the high voltage ( magnetron, capacitor, diode, wires to and from ):
    ...Use a metal ( not the shiny chrome type ) screw driver with a insulated handle to short across ( touch both at the same time ) the terminals of the high voltage capacitor to discharge it.

    From Jeff's site: http://www.applianceaid.com/component-testing.php

    Jake
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FIXED FGMV174KFC Frigidaire Microwave - No heat

joedotmac

Premium Member
Joined
Jan 20, 2021
Messages
11
Location
Texas
Model Number
FGMV174KFC
Brand
Frigidaire
Age
6-10 years
Frigidaire FGMV174KFC June 2013 manufacturing date.

No heat, other functions light, turntable, control panel work without issue.

Disassembled. Tested the three door switches. Top and bottom switch normally open, middle switch normally closed. All switches on Ohm meter test as expected when actuated. Bottom switch rocks in the mount slightly. Noticed some wear on the mount and the switch. Going to swap it with the top switch and add a little automotive fabric tape to bind it in position. Maybe swap it with the top switch.

Tested the diode, at 200 OMH meter setting it shows infinite or open both directions. Testing with a 9V battery polarity one side reads 5.10v. Flipping polarity zero volts. Not sure if this is a good or bad result.

Attempting to test the small circular thermo protectors or thermofuses (pictured) I'm seeing open on the nearest unit and closed (continuity) on the other. But I'm not sure of the known good condition state for these. Was thinking both should show continuity but again not sure.

Thanks for any insight.
IMG_5949.jpg IMG_5949.jpg
 

Dan O.

Appliance Tech
Staff member
Joined
Oct 9, 2004
Messages
5,658
Location
Ontario, Canada
Flipping polarity zero volts. Not sure if this is a good or bad result.

Yes. That is how a diode/rectifier works.

Was thinking both should show continuity but again not sure

Yes. They are limit thermostats, just one-time. They should usually have continuity unless tripped and then be permanently open.

LINK > 5304467699 Thermal Cutout, hood, 70c

LINK > 5304440023 Thermal Cutout, hood, 60c



I however don't know if a failure of either of the parts you pictured would result in the symptoms you stated. As near as I can tell those might just be for the vent fan. The oven cavity thermostat (at the following link) should shut down all power to the microwave, the lights, the fan, turntable and the control display together. In the exploded parts diagram it shows it mounted on top of the oven cavity (#17).

LINK > 5304502765 Thermal Cutout, cavity

There is yet another thermostat that might shut down just the heat. The description in the parts list says "Fuse, magnetron" which would often be mounted right on the magnetron tube. Someone might want to locate and test it as well. It appears to look slightly different than the others.

LINK > Thermal Fuse, Magnetron


If your exhaust fan is also not working, it might be the result of one of the thermostats that you've already tested and the heating a separate problem.

JMO

Dan O.
 

joedotmac

Premium Member
Joined
Jan 20, 2021
Messages
11
Location
Texas
Yes. They are limit thermostats, just one-time. They should have continuity unless tripped and then be permanently open.

LINK > 5304467699 Thermal Cutout, hood, 70c

LINK > 5304440023 Thermal Cutout, hood, 60c

I used page 2 on this copy of the manual for the diagram, easy on the old eyes. Page 2 Diagram FGMV174KFC

Tested 5304467699 Thermal Cutout, hood, 70c #124 whirlpool diagram shows no continuity (nearest component pictured in original post) <- leaning on this as a bad test and component

Tested 5304440023 Thermal Cutout, hood, 60c #5 whirlpool diagram shows continuity (furthest component pictured in original post)

I however don't know if a failure of either of the parts you pictured would result in the symptoms you stated. As near as I can tell those might just be for the vent fan. The oven cavity thermostat (at the following link) should shut down all power to the microwave, the lights, the fan, turntable and the control display together. In the exploded parts diagram it shows it mounted on top of the oven cavity (#17).

LINK > 5304502765 Thermal Cutout, cavity

There is yet another thermostat that might shut down just the heat. The description in the parts list says "Fuse, magnetron" which would often be mounted right on the magnetron tube. Someone might want to locate and test it as well. It appears to look slightly different than the others.

I'm unable to find 5304502765 in the whirlpool diagram. I did find # 17 on whirlpool diagram 5303319550 Fuse, Mangetron but I'm not locating it on the unit. I'll provide a picture. I do think I've located #15 on the diagram 5304467699 Thermal Cutout, cavity/hood fan, 70C it's hidden behind the front panel. I'll have to see about getting access to it.

If your exhaust fan is also not working, it might be the result of one of the thermostats that you've already tested and the heating a separate problem.

I haven't checked the exhaust fan. I thought it was working. But to verify I'll have to reassemble this thing.

I did isolate test the Magnetron itself 5304463439 Magnetron and it tested at .8 Ohm

Where's #17 5303319550 Fuse, Mangetron ?

IMG_5961.jpg IMG_5960.jpg
 

Dan O.

Appliance Tech
Staff member
Joined
Oct 9, 2004
Messages
5,658
Location
Ontario, Canada
joedotmac said:
5303319550 Fuse, Mangetron but I'm not locating it on the unit.

The magnetron tube thermal fuse is usually mounted directly onto the magnetron tube.

I do think I've located #15 on the diagram (5304467699 Thermal Cutout, cavity/hood fan, 70C) it's hidden behind the front panel.

# 15 is shown on the top, left side of the oven cavity. It is # 5304502765. It would usually be attached right onto the oven cavity to monitor its temperature. It looks to be by the stirrer motor at the top... if the diagram is at all close.


Dan O.
 

Dan O.

Appliance Tech
Staff member
Joined
Oct 9, 2004
Messages
5,658
Location
Ontario, Canada
The thermal fuse is a separate part.
 

joedotmac

Premium Member
Joined
Jan 20, 2021
Messages
11
Location
Texas
# 15 is shown on the top, left side of the oven cavity. It is # 5304502765. It would usually be attached right onto the oven cavity to monitor its temperature. It looks to be by the stirrer motor at the top... if the diagram is at all close.

I think where I'm getting crossed up is the diagram referenced here for the parts has differences to my unit.

I'm using a diagram from -> Page 2 FGMV174KFC This unit more or so matches the unit I've pulled apart. The differences are subtle, and some part numbers are different.

I was able to locate #15 5304440032 Thermal Cutout, oven cavity, it tested with continuity.

FGMV174KFCdiag.png

I went ahead and ordered #124 5304467699 Thermal Cutout, cavity/hood fan, 70C

Thanks for the help Dan. I'll report back once the part arrives this week.
 

joedotmac

Premium Member
Joined
Jan 20, 2021
Messages
11
Location
Texas
I was able to locate the #17 5303319550 Fuse, magnetron, tested validated continuity. Had to remove the black composite cover #54 Exhaust hood to access. I did find something interesting. It appears light oil or very light grease under the left fan assembly. There's oil pooled about a quarter size below, on the sides of the housing. Finding oil here normal? I wiped it up. Took pictures after I cleaned it up. The squirrel cage had been slinging some of this oil around because it was splattering to the front side of the exhaust hood.

Correlation between the hood fan having oil under it and the 5304467699 Thermal Cutout with no continuity?

IMG_5962.jpg IMG_5963.jpg
 

Dan O.

Appliance Tech
Staff member
Joined
Oct 9, 2004
Messages
5,658
Location
Ontario, Canada
joedotmac said:
I think where I'm getting crossed up is the diagram referenced here for the parts has differences to my unit.

Exploded view diagrams are NOT blueprints. They are general representations of the product only. Some parts may not even be illustrated or some that are may not even be found on the actual unit involved.

joedotmac said:
Correlation between the hood fan having oil under it and the 5304467699 Thermal Cutout with no continuity?

Is the protector attached to it or did the oil drip onto it? If not, no. Thermal protectors open due to the temperature of what they're mounted to.

I have no idea if oil is a particular issue with that model but other motors have been known seep some oil. I imagine it depends on how it was assembled and how much is required for the motor design to begin with. It's probably better than too little oil?

JMO

Dan O.
 
Last edited:

joedotmac

Premium Member
Joined
Jan 20, 2021
Messages
11
Location
Texas
Received and replace #124 5304467699 Thermal Cutout, cavity/hood fan, 70C. Plugging in power to the unit, the exhaust fan came un unexpected. Pressing the fan button will sequence through speed changes but the fan never turns off. Seem on the Fan Thermal Cutout is normally open switch. Placed back in the previous thermal cutout switch normal fan operation returned.
 

joedotmac

Premium Member
Joined
Jan 20, 2021
Messages
11
Location
Texas
No good answers here but all the testing was inconclusive. Went through thorough extensive testing of door switches, thermal cutoff switches, diode, transformer magnetron, capacitor ->

Replaced the magnetron, fixed the unit. Thanks!
 

Dan O.

Appliance Tech
Staff member
Joined
Oct 9, 2004
Messages
5,658
Location
Ontario, Canada
joedotmac said:
Replaced the magnetron, fixed the unit

That's odd since you said it tested as expected but I'm glad you were able to get to the bottom of it. Thanks for the update.

Dan O.
 
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