Issues with Primus heating system

[JoeWilliamson]

I'm still working on my Primus system. Do any of the SP veterans know where the snap disks are located? Especially for the fan under the couch? I have a 1991 SP36.
Thanks,
Joe

[Randy Dupree]

Joe,the fan is on the convertor,and the snap disc will be on the hose going to the convector.
It will be close by,all you can do is open the cabinet where the fan is and do a search.
even if the snap disc is still zip tied to the hose,the hose may be dirty and that dirt may be insulating the disc.
i take the disc off,clean the hose and disc and use new zip ties to attach it back.

[Alever]

I found while working on mine that there was only power to the fan controller when the Primus controller was switched calling for heat. As soon as the thermostat on the Primus would stop calling for heat and the green light would turn off, the fans would stop. Turn the thermostat up till green light turned back on the fans would start right back up.
Just a surprise I found in mine about the fans.
Oh the lines were up to temperature at the time. It takes a long time for the fans to come on when the bus is cold. I thought the snap discs were bad due to the length of time it took for fans to come on.

[JoeWilliamson]

Is this the snap disc, in the photo? If so, then I'll take it off, clean, and re-install. I'm skeptical though because it looks fairly clean and a solid connection. Is it possible for the snap disc to go bad? A friend put power to the fan adjusting knob, and got the fan to run. And we changed a bad fuse.

I found another one for the fan under the kitchen. Both are not working at present. This will be a very easy fix if the snap disc connection is the problem. Boy do I hope that is the source of the problem.

Many thinks to Steve and others for your help.

[Randy Dupree]

Thats the disc,jump the wires to see if the fan runs,you have to have heat from some source to check the disc itself.

[JoeWilliamson]

I jumped the wires on the scan disc under the couch, but it did not turn the fan on. Nor did a hot pipe with a newly cleaned and installed disc. I jumped the wires on the fan adjustment knob, and it did turn the fan on. The wires from the fan adjustment knob are different colors than those from the scan disc. Where do the wires from the scan disc go? I think the source of my problem might be with a fuse, broken wire, or other problem upstream from the scan disc.

[Randy Dupree]

Originally Posted by JoeWilliamson

I jumped the wires on the scan disc under the couch, but it did not turn the fan on. Nor did a hot pipe with a newly cleaned and installed disc. I jumped the wires on the fan adjustment knob, and it did turn the fan on. The wires from the fan adjustment knob are different colors than those from the scan disc. Where do the wires from the scan disc go? I think the source of my problem might be with a fuse, broken wire, or other problem upstream from the scan disc.

You jumped the wires on the adjustment knob and the fan runs?
That makes me think the adjustment knob is bad.

[bwinter1946]

Originally Posted by Randy Dupree

You jumped the wires on the adjustment knob and the fan runs?
That makes me think the adjustment knob is bad.

Agreed. It shows the switch has power.

[JoeWilliamson]

I'll try a new adjustment knob- see if that fixes the problem.

[Randy Dupree]

Originally Posted by JoeWilliamson

I'll try a new adjustment knob- see if that fixes the problem.

take one that works out of the coach and use it for a test.