My Jenn Air JGS8850 takes over 10 minutes to preheat to, say, 400*. Is this normal?

Unscrew the gas igniter button and insert the battery positive end upwards. Then screw the button cap back on. A tip, don't let it rain onto that button. Torrential rain stopped my igniter working for 6 months.

Page 9 of your manual refers

https://www.manualslib.com/manual/705964/Jenn-Air-720-0336.html?page=9#manual

Parts

https://www.appliancefactoryparts.com/gasgrillparts/jenn-air/720-0336.html

..

It's faulty and in some sort of self protect mode. You need a service call or you can try some of the fixes here.

FIXED - WW2780 Jenn-air oven keeps shutting off ...

www.applianceblog.com > mainforums > threads > ww...

Feb 15, 2012 - Hi.... I have a Jenn-air oven model WW2780 that keeps shutting off after being turned on, almost always during the preheat. From what I have ... Missing: WW27430P ‎' Must include: WW27430P

Jenn Air Range Stove Oven - Oven Won't Turn Off - Repair ...

www.repairclinic.com > RepairHelp > Jenn-Air-Oven-...

Here are the most common reasons your Jenn Air oven won't turn off - and the ... Enter model number to search for the required part specific to your product.

HOW-TO: Jenn-Air Oven WW27430P Door won't close

www.appliancepartspros.com > repair-help > ww27430...

Door won't close is the most common symptom for Jenn-Air WW27430P. ... I have a Jennair jjw9630cas double wall oven, and after a few years I noticed that the light would not go out, first in the bottom ... Door pulls shut and li8ght stays off.

HOW-TO: Jenn-Air Oven WW27430P Won't start or doesn't start

www.appliancepartspros.com > repair-help > ww27430...

How to Replace Oven Temperature Sensor Kit for Jenn-Air WW27430P Won't start # ... Jenn Air stove JDS9860CDB00 error code 1d11 oven not shutting off. ... Very easy on this and other models with this sensor-- just two screws holding it in ... Rating: 5 · ‎123 reviews

..

replace both door hinges

turn power off remove gill in oven remove fan blade now remove back panel and remove convection fan motor and wirers Now revere procedure to install new fan motor Cheers

You might find an answer here:
http://steprightupmanuals.com/oven-and-range-service-manuals/jenn-air-oven-and-range-service-manuals/jenn-air-jgs8750-jgs8850-range-service-manual
prem

Yeah the coil in the relay is bad ,replace relay

Hello,

Very common issue on these units and I have replaced the board to fix this issue. You will need a new erc, let me know,

http://www.appliancerepairlesson.com/

you could have a bad probe receptacle. Or a board problem. Kill power to oven, wait 10 min, cross your fingers and restore power.

possible thermostat is sticking

I have just checked the baking guide in the manual and have found that it may not be us after all. (Maybe this is why they telll us to read the whole manual. Well, I never have) According to the cooking time for Baking, the range is very extensive. For example, an angel cake at 350 could take from 28-50 minutes, buscuits at 375-400 could take 8-16 minutes, layer cakes at 350-375 could take 25-40 minutes, pound cakes at 325-350 could take 45-70 minutes and fresh pies at 400-450 could take 35-60 minutes. Basically, the baking directions on the box means absolutely nothing to use Amana oven owners. We have no choice but to cook our food or baked goods until they are cooked, whenever that may be. :) Linda