frymaster hot hi failure

[western]

I'm working on a frymaster deep fryer at a mcdonald's. I have been having intermittent hot hi and probe failure problems. I watch the temperature show very erratic readings intermittenly then work normally most of the time. I already replaced the interface board, wiring harnesses, front panel (board), temperature probe, ingitor cables. Tech support thinks it's an interference problem with the ignitor cables, but it happens when not calling for heat. I actually have this problem on split vats at 2 mcdonald's. I'm geussing it may be a heat issue so I tried putting a small cooling fan toward the control box but it didn't seem to work. Any help would be appreciated.

[RuudInstaller]

I had this happen once at a McD's and after changing everthing you did, I found it was the transformer giving inconsistent voltage which leads to erratic probe readings. each vat has its own transformer and it is dual voltage 12vac and 24vac. Hope this helps.

[western]

Thank's, I'll check it and post an update

[crymtide]

You could also have drain switch issues as the control power routes through this switch (switches on a split vat). It can cause erratic power through partial grounding or high resistance. I've never seen these controls affected by heat. I have had resistance issues with high limits in pitcos though not fry master. The high resistance in the pitcos were taking out the transformers through high amp draw.

[RuudInstaller]

Drain switch only cuts power to gas valve on the Frymaster fryers at McDonalds. The controller is powered by 12vac directly from the transformer in the back.

[hs2kang]

I had this happen once at a McD's and after changing everthing you did, I found it was the transformer giving inconsistent voltage which leads to erratic probe readings. each vat has its own transformer and it is dual voltage 12vac and 24vac. Hope this helps.

Thank you for your comment.
I have exactly same problem at a KFC. The problem can not be reset by just turning controller off/on, but can be reset after disconnect/reconnect the harness between controller and interface board. Is this same with your case?

[caheiman30]

I work for a McDonald's Owner on there in-house maintenance team, and I have seen this when the vat heats up to fast because the blower wheel that feeds air to the ignitor is closed to much. Once opening the housing vent up to allow more air to flow the problem went away.

I'm working on a frymaster deep fryer at a mcdonald's. I have been having intermittent hot hi and probe failure problems. I watch the temperature show very erratic readings intermittenly then work normally most of the time. I already replaced the interface board, wiring harnesses, front panel (board), temperature probe, ingitor cables. Tech support thinks it's an interference problem with the ignitor cables, but it happens when not calling for heat. I actually have this problem on split vats at 2 mcdonald's. I'm geussing it may be a heat issue so I tried putting a small cooling fan toward the control box but it didn't seem to work. Any help would be appreciated.

[mwright]

What's the model # on your unit? If its the same or close to mine there is also a high limit sensor on it. I didn't see you say you changed that. I had mine going out on high temp and changed the temp probe but didn't take care of it. Changed the high limit and all was fine.
Just a little advise. If you have to change either the temp probe or the high limit, change both of them. For the price of them and the pain it is to change them, change them both and get it don't. I've found that if one goes bad the other isn't far behind.
Hope this helps.

[western]

thanks for the help, sorry I didn't update but it was a connector to the back of the board.

[rango]

Just an FYI for HOT-HI on MCD's fryers by Frymaster. It means that the computer is reading a temp that is over the set point. First thing to check is whether or not the TC is covered with carbon (insulator) which will cause delayed readings. Second is for grease (insulator) on the plug terminals on the back of the interface board. The TC will crap up on electrics more than on gas, especially if the store does not boil out the vats regularly. Just throwing this out there for future reference.

Rango