Sharp microwave/convection oven venting problem

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Sharp microwave/convection oven venting problem

July 11, 2010, 07:30:50 pm

Our 2003 U295 3610 coach has a Sharp model R-1870 microwave/convection oven (8/02 manufacture date), and it is the original factory-installed oven as near as I can tell. See attached image.

There are two fans. One comes on when the microwave/convection oven is on and the other is turned on by a push switch on the lower right corner of the microwave.

There is a vent grating on the top of the microwave, but there is no air movement from this grate with either or both fans on.

There are two metal-weave fan inlets on the bottom of the microwave, above the cook top, but there is no indication of air movement up through them when the fan switch is turned on (to either hi or lo setting).

On the roof there are two vents. One appears to be above the microwave and the other above the refrigerator. The one over the microwave does transmit a lot of noise from either fan, but there is no evidence of air movement.

The bottom line is that both fans make a lot of noise when on, but move little or no air from the microwave/convection oven, nor from the cook top fan, to outside of the coach.

In looking at the installation manual (see attached PDF file downloaded from the Sharp website), we are wondering if the oven was installed correctly at the factory. There are three venting options described in the manual (recirculating, horizontal, and vertical venting), which require the hood fan unit and the exhaust damper assembly to be manually turned depending on which of the three venting options is desired.

Does anyone else have a similar experience or know that their fan(s) work with this microwave?

Thanks in advance,

Pat

Re: Sharp microwave/convection oven venting problem

Reply #1 – July 11, 2010, 07:48:44 pm

Quote from: Patricia – July 11, 2010, 07:30:50 pm

There is a vent grating on the top of the microwave, but there is no air movement from this grate with either or both fans on.

There are two metal-weave fan inlets on the bottom of the microwave, above the cook top, but there is no indication of air movement up through them when the fan switch is turned on (to either hi or lo setting).

Does anyone else have a similar experience or know that their fan(s) work with this microwave?

Pat,

I just took a small piece of paper and tested ours (also the same convection/micro, also a 2003 coach).

Using the fan button on the front of the oven, the piece of paper is sucked against the metal filters and held there. Not strongly, but good enough to defy gravity on both high and low settings. This shows some air flow with the external fan, so there must be some venting.

Same piece of paper is not at all deflected when held over the grate that's above the door of the micro, indicating (to me, at least) that the duct baffle is not in the "recirculate" position.

I have not gotten on the roof to see if there's airflow there with the fan on. Might need a single malt or two first since I have a fear of heights

I have read of problems with the duct baffle on these ovens hanging up (not necessarily in the RV application, but in general). When that happens, though, the symptoms are an oven that suddenly shuts itself off during preheat or bake when set to higher temperatures.

Are you still dealing with "chicken"?

Michelle

Re: Sharp microwave/convection oven venting problem

Reply #2 – July 11, 2010, 09:06:54 pm

My last two coaches did not have the microwave vent outside but my 01 does. It is ok but I had to put a dam of silicone up there on the front of the vent on the roof to prevent rainwater from coming in when I was driving. Therefore, I am of mixed opinion on the outside vent and would have liked to see a side vent like the dryer vent.

Re: Sharp microwave/convection oven venting problem

Reply #3 – July 12, 2010, 01:24:00 am

Quote from: Steve & Michelle – July 11, 2010, 07:48:44 pm

I just took a small piece of paper and tested ours (also the same convection/micro, also a 2003 coach). Using the fan button on the front of the oven, the piece of paper is sucked against the metal filters and held there. Not strongly, but good enough to defy gravity on both high and low settings. This shows some air flow with the external fan, so there must be some venting.

Thanks so much for testing your same model, Michelle! That leads credence to my theory that our hood fan unit and exhaust damper assembly may well have been moved (by FOT installers) out of the (Sharp) factory default recirculating position into the horizontal rather than vertical exhaust position.

Quote from: Steve & Michelle – July 11, 2010, 07:48:44 pm

Are you still dealing with "chicken"?

There is now only a very faint "hint" of "eau de country diner" (ie, old roasted chicken odor) in the adjacent cabinet. Needless to say, even if we get the oven properly exhausted, I'm not so sure I would attempt another convection-roasted chicken again!

Looks like we may need to remove the oven from the mounting plate and check the position of the fan and damper. Have you (or anyone) attempted that?

Pat

Re: Sharp microwave/convection oven venting problem

Reply #4 – July 12, 2010, 05:40:59 am

It is easy to take down a couple screws up top and you lift it off the mounting bracket. It is an tough lift though since you are not under it but infront so two people make it easier.

Re: Sharp microwave/convection oven venting problem

Reply #5 – July 12, 2010, 01:52:34 pm

Pat, Our oven is a Model 1871, dated 10/01, Seems odd that the 1871 was made before your 1870, huh?

I tried the small piece of paper test too with the following results:
When pushing the button (high & low) the paper sticks to the grill above the door all the way from left to right. It also sticks to the metal filters under the oven, but the suction is noticeably stronger on the left filter.
When the Convection oven is ON, the paper sticks to the grill above the door, but only at the 4" segment at the right directly above the digital display.
We were concerned about this because we were trying to figure out if the oven needed a charcoal filter. We think it is vented outside through the front roof vent so it does not use a charcoal filter. We haven't checked this from the roof though, but we can smell the bacon cooking while standing alongside the coach!
Let us know what you do and how it works after take the oven down.

Re: Sharp microwave/convection oven venting problem

Reply #6 – July 12, 2010, 07:21:26 pm

Quote from: Dick S – July 12, 2010, 01:52:34 pm

Our oven is a Model 1871, dated 10/01, Seems odd that the 1871 was made before your 1870, huh?

The last digit is just the color code

1870 is black, 1871 is white.

Re: Sharp microwave/convection oven venting problem

Reply #7 – July 12, 2010, 07:52:28 pm

What I am about to say is a little like asking what is a good polish for your coach and have someone tell you to get a full body paint job. Now, having said that --

Couple of thoughts on the microwave. It is VERY heavy. At least 96 pounds. So be prepared and be careful. Last October or November we took out the old malfunctioning Sharp and installed a GE Advantium 120. Model SCA1000. DW is a very good and a very fussy baker. Her new oven makes fabulous cookies, scones and pumpkin pies.

A few readers here can attest to her baking skills. Before the Advantium her baked goodies were ...... well,
not so good.

Re: Sharp microwave/convection oven venting problem

Reply #8 – July 12, 2010, 10:49:37 pm

Quote from: George Stoltz – July 12, 2010, 07:52:28 pm

Last October or November we took out the old malfunctioning Sharp and installed a GE Advantium 120. Model SCA1000.

IIRC, you can't turn off the turntable in the 120V Advantium, correct? That eliminated it as a potential upgrade for us. I have some favorite recipes whose pans preclude rotation in an OTR oven.

-M

Re: Sharp microwave/convection oven venting problem

Reply #9 – July 12, 2010, 11:07:00 pm

Correct. The turntable spins whenever cooking is underway.

Re: Sharp microwave/convection oven venting problem

Reply #10 – August 30, 2010, 10:32:56 pm

We're thinking of upgrading to the GE also, since ours won't heat higher than ~290 on convection. This was discovered last Thanksgiving, getting ready for a potluck...

.

On turntable rotation - can't the turntable just be removed for the baking? Alternatively, I'd be willing to bet that you could pull the cover off the GE and add a switch to the turntable motor, (this would obviously void the warranty) and if we upgrade, I may do just that.

Re: Sharp microwave/convection oven venting problem

Reply #11 – August 30, 2010, 10:46:59 pm

That is probably a big mistake on the part of GE in that the turntable can not be turned off. When it calls for baking, the pan has to be small enough to not touch the sides as it rotates. Now, having said that, you could remove the ring that rotates and use 4 small blocks of something to elevate a larger dish to just above the center shaft that rotates. Then bake.

But don't blame me if your recipe fails

Re: Sharp microwave/convection oven venting problem

Reply #12 – August 30, 2010, 10:51:06 pm

Quote from: Dave Katsuki – August 30, 2010, 10:32:56 pm

On turntable rotation - can't the turntable just be removed for the baking?

I keep hoping GE introduces an upgraded model. At one point, Sears offered their Kenmore-branded version of the Advantium 120 OTR which DID have the turntable-off selection. Unfortunately, it doesn't seem to be offered at the moment (should have ordered it when I saw it).

-M

Re: Sharp microwave/convection oven venting problem

Reply #13 – March 21, 2011, 09:20:50 am

Once we left Nac earlier this month, I neglected to follow-up on the outcome of FOT's inspection of my microwave/convection oven venting problem which started this thread. My original theory was that our hood fan unit and exhaust damper assembly may well have been moved (by FOT installers or others) out of the (Sharp) factory default recirculating position into the horizontal rather than vertical exhaust position.

The problem turned out to be pilot error! The fans (both over-the-range and the interior micro/convection oven) actually need a window open (even slightly) and the Fantastic fan in the hall running due to the almost air-tight compartment we live in when all windows/door are closed.

One of the techs (Bob) demonstrated the pull of air from the over-the-range fan - in particular with the window open/shut. He also went up on the roof to the vent and confirmed that it was indeed venting properly. Previously (back in NM), George had gone up on the roof to check on whether the oven was venting, but found no noticeable air movement. However, he was checking with the vent cover on, and from the center of the roof. On the other hand, Bob (at FOT) was on a ladder, checking from the outside edge of the roof - and with the vent cover off. In addition, Bob had the door of the coach and the kitchen window open. George went up the ladder to verify and, indeed, there was air coming from the oven's roof vent.

I was familiar with the Fantastic fan's requirement of a window to be open to move air for a cooling breeze - but didn't connect it with the micro/convection oven's ability to vent, as well as the over-the-range fan's ability to function efficiently, too.

Thus, my point in resurrecting this old thread is to share my "aha" moment... at least crack the window open (and even turn on the hall fan) for the fan to move air out of the coach.

And a P.S. for George.... As you noted I don't need a full body paint job, when all I'm asking is which polish to use. BUT, should the Sharp ever fail, I would seriously consider an Advantium. However, like Michelle, I really appreciate the Sharp's sensor cooking - best ever - and I really wouldn't want to give that up (along with the Sharp's turntable rotation). So, like Scarlett, I'll think about it tomorrow....

Re: Sharp microwave/convection oven venting problem

Reply #14 – March 21, 2011, 09:40:51 am

Gee Whiz! Thanks for posting this ... I never thought!

Re: Sharp microwave/convection oven venting problem

Reply #15 – March 21, 2011, 09:50:38 am

Quote from: Carol Savournin – March 21, 2011, 09:40:51 am

I never thought!

It is amazing - to me, too - which explains why there is still the occasional "reminder" of a roasting chicken episode last fall... ie, a very minor scent of "country diner" inside the cabinet adjacent to the oven!

Re: Sharp microwave/convection oven venting problem

Reply #16 – March 21, 2011, 10:45:02 am

Pat, thanks for having the courage to post the real cause of the problem. None of us experts thought of that possibility. It's a bit like all of the electrical problems many of us including myself (more than once) have had when the battery disconnect switch by the door is off. BTW it is a disconnect switch in name only as it does not disconnect any batteries, it only disconnects 12 volt electrical power to mainly the house lights, and some other items. On my coach things that still work with it off are the refrigerator, inverter, LP and CO detectors, travel function only of the leveling system, and the generator will still start and run. Sorry, I got off topic here.

Re: Sharp microwave/convection oven venting problem

Reply #17 – March 21, 2011, 02:14:53 pm

Quote

RE: " BUT, should the Sharp ever fail, I would seriously consider an Advantium. However, like Michelle, I really appreciate the Sharp's sensor cooking - best ever - and I really wouldn't want to give that up (along with the Sharp's turntable rotation)."

Note that only Sharp has the door hinged a couple of inches from the end. All other brands have their hinges at the end which prevents door from opening fully if there is a cabinet or wall next to the microwave. Also Sharp is the only brand without a door handle that protrudes into the room which can also interfere with wall. I hear that the Advantium only works when time is set.
We recently took our Sharp off the wall, to replace the convection oven temperature thermistor sensor and dismounting went ok.

Re: Sharp microwave/convection oven venting problem

Reply #18 – March 21, 2011, 04:30:44 pm

Quote from: Barry & Cindy – March 21, 2011, 02:14:53 pm

only Sharp has the door hinged a couple of inches from the end. All other brands have their hinges at the end which prevents door from opening fully if there is a cabinet or wall next to the microwave. Also Sharp is the only brand without a door handle that protrudes into the room which can also interfere with wall.

Excellent point - and thank you for pointing it out. In our case, there is only a partial adjacency to a cabinet on the left side, but if another brand of oven were hinged on the right, it would indeed be a problem (see photo below). Will definitely keep it in mind!

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Re: Sharp microwave/convection oven venting problem

Reply #19 – March 22, 2011, 10:29:07 pm

In an earlier post, I lamented about removing the Sharp, and installing a brand new Kenmore micro/conv. oven, only to find the door wouldn't open due to the hinge placement, and the adjoining cabinet. Replacing the micro really isn't a complex task, except as earlier stated, it is sometimes a two-person operation. Ended up getting a Kenmore micro/infrared oven, as none of the micro/conv. models I could find at the time were hinged correctly.

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