JennAir JGRP536WP01 will not maintain temp setting

[SamP]

Model Number

JGRP536WP01

Brand

Jenn-Air

Age

6-10 years

JGRP536WP01 Jennair oven won't maintain temp setting. This problem was more intermittent earlier in the year but if I switched from bake to convect bake or convect bake to bake it seemed to go back to working right. I ohmed out the temp sensor and it tested ok at room temp so I didn't replace it. I wanted to watch the burner to physically see what was happening but there is a cover over the burner. After I remove it to watch the burner the oven seemed to work properly. I noticed the cover was bent from heat and wondered if the fan/vent system could be causing the problem by interrupting the flame/burner. I decided to monitor the operation and for a few months it worked fine. I continued to use the oven and put foil over the lowest grate and it seemed to work ok so I ordered a new cover. Now the problem has returned and happens all the time whether the cover is on or not. I purchased an oven temp sensor and replaced it cause I thought maybe it might be at fault when hot and every site says its the problem 99% of the time. I still have the problem. So here's what happens - I set oven temp to 350. It preheats and burner stays lit until 330-332 and then the burner shuts off. According to the display the temp slowly rises to 350 then it switches over to bake or convection bake (whatever I had selected). To check the temp of the oven I added a Fluke DMM probe to the inside of the oven and at about 290-300 I hear the ignitor and the burner re-light and temp climbs back up to around 330. This continues for about 30 minutes and Im thinking the temperature is a little off but I try to bake things and sometimes I have to give a little more bake time so it's not so bad. Then I notice that after about 30 minutes the temp slowly lowers and the DMM tells me the temp is at 240-260 and won't go higher. At this stage I can't bake right. So I take the burner cover back off and I notice about every 30 seconds I hear the ignitor snap and the burner lights but goes out after about 2-3 seconds. The temp goes up about 5-7 degrees and the oven temp stays around 240-260 according to the DMM. It works like this whether it's on bake or convect bake. Maybe its normal but the display stays at 350 and I'm thinking it stays there cause its not the oven temp but the temp that was selected. During the preheat mode the display shows actual oven temp and climbs pretty accurately. Every other function of this oven including broil works correctly. Intermittent operation is a head ache for anyone but at least I can now rely on this range to bake incorrectly most or all of the time!! I bought this range new about 7 years ago. This pricey range seems to have a mind of its own and I would appreciate any repair troubleshooting or help.

 

[SamP]

Because this situation is intermittent I am monitoring a few more instances of usage with DMM readings and will provide the info. In the meantime I,m thinkin I have the wrong tech sheet and wonder if anyone can get the correct one? To enter diagnostic mode my sheet tells me to press three different numbers in sequence three times in a row within 8 seconds but nowhere on my screen are numbers to press. There is a "modes" tab but diagnostics is not listed anywhere. I'm not seeing any codes but I wanted to check just to see.

 

[SamP]

After thinking about it I went to the display pad and just pressed three same buttons three times in sequence within 8 seconds and was able to reach the diagnostics screen. No codes. I guess the tech sheet supplied Most likely is the correct one. Still monitoring the oven with the DMM and it's acting differently each time but so far what seems to be common is that soon into the bake mode the burner lights, then goes out, and after a few seconds relights and stays lit but shuts off 20-40 degrees under the selected temp almost always. I don't know who to thank but this blog is quite helpful as the more pages I view the more I learn about possible areas to check. I saw someone else post and said they calibrated the temperature setting up to 20. Do you this might help or is it something I should at least try or add to the monitoring results?