How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Ed Michaels Your Own Question

Ed Michaels
Ed Michaels, Appliance Technician
Category: Appliance
Satisfied Customers: 706
Experience:  my company installs and maintains appliances in NYC
Type Your Appliance Question Here...
Ed Michaels is online now
A new question is answered every 9 seconds

Whirlpool GH7208XRQ microwave exhaust fan runs continously

Customer Question

Whirlpool GH7208XRQ microwave exhaust fan runs continously on High setting, cannot be shutoff. Is this maybe a resistor prooblem or switch ?
Submitted: 1 year ago.
Category: Appliance
Expert:  Ed Michaels replied 1 year ago.

Hi, First of all, operating a microwave without an exhaust fan is a fire and possibly an explosion hazard. There are very high heats generated. The fan is operated by a control board relay. It can't be repaired. Failing control board needs to be traced, tested, and replaced. and it may not be the only problem.A schematic would be necessary but are not published due to danger of servicing high voltage circuits.

Unfortunately, it's not really a DIY project unless you're an electronics technician. If you are, the parts alone are in the $130 range. Here's the parts site.

Here's the situation. Much like televisions, microwaves are full of very high voltage (4000v-5000v) even when unplugged, and require care , schematic diagrams(unavailable to DIY servicers), and electronics experience to service. They are increasingly controlled by miniature pc boards and chips, impossible to repair, difficult to test, and expensive to replace. Also like televisions, once they're out of warrantee, parts and labor (if you can find them) can often approach or exceed the cost of a new machine. Therefore, like TVs, Microwaves have become cheaper to replace than to service, and service has become increasingly hard to find. You can check repair costs by clicking on SearsRepair for their plan. Cost could be weighed against cost of new unit with a new warrantee. It's up to you. I hope this answer is helpful if not welcome. Either way, let me know what you think. ed

Customer: replied 1 year ago.

Ed, I was not clear enough. NOT the exhaust fan inside the microwave, rather the hood fan/blower underneath for the stove/range exhaust (an option I think). There are four positions plus off. Currently the blower runs on the highest speed and cannot be turned off. I just bulled the wire that powers the blower.


The parts book shows two resistors (a 50 watt & a 25 watt) and I think one is for the blower and maybe shorted. Thus with no resistance, blower would run on high.


Am I close ?

Expert:  Ed Michaels replied 1 year ago.
That's a whole different thing. that sounds like the 50W and the 25W separately and in series would give the 3 slow positions and no resistance at all would give full speed(what you have now) the problem is fixing it. The resistors are not the problem. The switch is shorted out.(no resistance top speed) If its a mechanical rotary switch you may be able to access it and replace it. If its a touchpad, and I think it is, the touchpad would have to be replaced. The parts list shows part 6 electronic control panel. You could verify when ordering that this is the speed control. The thing is, The schematic is only available to registered repair men. This site does not support my accessing controlled service literature for DIY purposes. You will be on your own in accessing and replacing this piece. Alternatively, as a work-around you can purchase any kind of recessed or surface mount 120v switch like this and wire it in series with your fan.and control it separately (one speed only, but at least its high speed, the only speed necessary.) How does this sound? ed
Expert:  Ed Michaels replied 1 year ago.

Hi, we seem to have lost contact. I hope my answer was helpful. Let me know if I can help further. Ed

Customer: replied 1 year ago.

Ed:


Your answer was helpful. I called both Sears & Whirlpool customer service to order the fan control, neither was helpful (actually they were awful), so I took a chance and ordered it anyway.


I'll report back when I have the control. Any idea how to open the microwave sheetmetal box ? I don't yet see anyway to access the control which is behind the buttons on the front. I've opened up the bottom where the ventilation fan is, no help. I'm persistent & mechanical.


Marvin

Expert:  Ed Michaels replied 1 year ago.
Hi Marvin, I'm persistent and mechanical too, and I've been down the road you are on. I hope I didn't lead you down that road. I really think the wall switch is the best answer. These hybrid machines are not designed for easy repair. They are designed to squeeze a microwave and hood into a tiny space. Most repairmen won't work on them. They just replace them. If you manage to replace control panel, it may not fix the problem, and the part may very well not be returnable. Having said all the negative things, take a look through this manual. It's general but informative. Start with the fan and trace the circuits back. Read about the High Voltage section. Be very careful. It can literally be lethal. Its up to you. Best of luck. ed
Expert:  Ed Michaels replied 1 year ago.
Hi Marvin, Let me know how it goes. ed
Customer: replied 1 year ago.

Ed:


The new fan control fixed my problem. Thanks again for your help.


Marvin


 

Expert:  Ed Michaels replied 1 year ago.

Great news. persistence pays off. Glad I could help.

Customer: replied 1 year ago.

Ed:


I still have a problem. The M/W worked for fine awhile except for the turntable. I didn't reconnect the two wires when reinstalling the bottom cover. When I open the cover, one of the hanging wires touched the cover and shorted. No power to the microwave touch screen now. The house circuit breaker didn't throw. I removed the 20 amp line fuse and it tested good on a simple continunity test (resistance).


 


Note sure if my fuse test was good ? I'll recheck the fuse (or get a new one) and see if the exhaust hood fan & lights work. I also check that I have power to the A/C filter. If yes, I'm thinking the primary or secondary interlock switches, the hood fan & lights do not go thru this circuit. Any other ideas ? The manual suggests if the 20 amp fuse blows the interlock switches need to be replaced.


 


Marvin


 

Expert:  Ed Michaels replied 1 year ago.

Hi marvin, this is exactly the kind of problem I warned you against. It sounds like the touch screen has blown. fuses do not protect against accidental short circuits.That manual is a class manual for supervised study. i recommended very simple repairs. I can't supervise an untrained technician at a distance. There is a limit to remote diagnosis. I sincerely XXXX XXX are careful around the HV section. I hope you accept this answer. and I wish you the best. ed

Expert:  Ed Michaels replied 1 year ago.
hi marvin, we seem to have lost contact. I hope my answer was helpful. ed
Customer: replied 1 year ago.

Yes I admit I made a mistake and now I intend to fix it.


BTW, I'm a professional safety engineer. I don't want to pay the outrageously expensive Sears repair technicians to come to my home ... I've had some bad experiences.

Expert:  Ed Michaels replied 1 year ago.

I wasn't saying you made a mistake. I was concerned for your safety. I was not aware you were an engineer. I'm relieved to hear it. I know of some pretty serious injuries from hobbyists working on microwaves. I give a lot of warnings. I'm sorry if I insulted you. Since your trained, here's something else you may find useful. REPAIR FAQ It's dated but very practical. Read the section about interlock switches. You'll see that they're designed to blow the line fuse when they're misaligned as well as when they're blown. also check the turntable motor for continuity and touchpad pcb for burnouts. That's most likely. Let me know how it goes. ed

Customer: replied 1 year ago.

Ed:


I have continuity on the turntable with some resistance. I have the door removed, how do I test the touchpad for burnouts ? There is a board and some panels.


I'm a mechanical engineer.


Marvin

Expert:  Ed Michaels replied 1 year ago.
Marvin, If you've eliminated the switches and motor,trace the circuit backwards from the short to damaged component. touchpad display panel should be right behind the touchpad or connected to it with a wiring harness. Burnouts will be visible on pcb as blackened areas. You may find a fuse on the pcb which you can check , otherwise pcb is not repairable. It seems at this point that the display board will need to be replaced. ed
Customer: replied 1 year ago.

Ed


I've tested the interlock switches as good and the main inline fuse is good. Parts list show a LCD module and elec-control on the door. The trouble shooting guide says replace the LCD module first, what do you think ? I assume the LCD module is the display board (which is completely black) ?


Everything must go thru the LCD, the vent fan and night lighs don't work either. The circuit diagram I have is tough to follow becasue its not for a touch screen model.


Marvin

Expert:  Ed Michaels replied 1 year ago.

 

Marvin, that sounds right. LCD means Liquid Crystal Display. check to see if it's returnable.ed

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • Thank you for the expeditious answer. It's good to know you're out there and awake in the wee hours when I finally have time to ask questions about my Jenn Air. Jean Riverhead, NY
< Last | Next >
  • Thank you for the expeditious answer. It's good to know you're out there and awake in the wee hours when I finally have time to ask questions about my Jenn Air. Jean Riverhead, NY
  • You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future. Jimmy Bagley, IA
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
 
 
 

Meet The Experts:

 
 
 
  • John

    Home Appliance Technician

    Satisfied Customers:

    13442
    Appliance repair business owner for over 43 years.
< Last | Next >
  • http://ww2.justanswer.com/uploads/docjohn174/2008-12-13_170143_johnask.jpg John's Avatar

    John

    Home Appliance Technician

    Satisfied Customers:

    13442
    Appliance repair business owner for over 43 years.
  • http://ww2.justanswer.com/uploads/tomgoe/2011-01-04_021913_2008-03-03_183612_phpexrmok_c2pm.jpg Tom Goellner's Avatar

    Tom Goellner

    Home Appliance Technician

    Satisfied Customers:

    1191
    32 yrs. experience servicing major appliances and HVAC equipment.
  • http://ww2.justanswer.com/uploads/MD/md2020/2012-6-6_20648_Selfpic.64x64.jpg Tyler Z.'s Avatar

    Tyler Z.

    Appliance Doc

    Satisfied Customers:

    51307
    7+ years being an appliance technician with factory training.
  • http://ww2.justanswer.com/uploads/bryanpaul52/2009-2-18_12031_0918081611.jpg Bryan's Avatar

    Bryan

    Home Appliance Technician

    Satisfied Customers:

    11158
    15 yrs. experience as a certified appliance technician.
  • http://ww2.justanswer.com/uploads/SM/smitty1486/2011-3-1_0145_Snapshotofme1.64x64.png Kelly's Avatar

    Kelly

    Appliance Technician

    Satisfied Customers:

    6493
    Highly accurate diagnostician with over 30 years experience!
  • http://ww2.justanswer.com/uploads/TH/TheHomeSmithy/2011-8-13_11146_homesmithy.500x500.64x64.jpg The Home Smithy's Avatar

    The Home Smithy

    Home Appliance Technician

    Satisfied Customers:

    5935
    30 years repairing appliances
  • http://ww2.justanswer.com/uploads/TE/Teamcold/2012-6-15_15028_HomeRepairsquarecopy.64x64.jpg Barry G.'s Avatar

    Barry G.

    Home Appliance Technician

    Satisfied Customers:

    5039
    27 years in home appliance repair. EPA refrigerant transition and recovery certification type I & II.
 
 
 

Related Appliance Questions