Holiday season greeting all,

I have a 2003 Marathon H3-45 with intermittent Webasto operation. On a typical Las Vegas cold morning (30s), while testing the unit, I turn on 12 V Heat switch and call for heat from thermostats (double push on heat buttons). The unit comes on as it should and the coach starts heating. After about 1-2 hours, I check the coach and Webasto turns off with cold air blowing into the coach. When I try to turn the Webasto back on right away, it starts (motor whirring and cold air from exhaust pipe) but never ignites the diesel heat. After a few minutes the unit turns off as it should with no ignition. If I wait long enough to cool off, the unit starts over just fine, and sometimes stays on cycling on and off as needed for heating.

Same issue when turning on Webasto through 12 V Water Heater. It is a hit and miss.

I had it checked from Marathon in Coburg earlier this year in July, and they saw similar issues. They services the unit and changed out the igniters and it worked fine when they tested it. Next time I tried it after leaving the shop, same intermittent operation started again.

Sounds very much like a control box or sensor type problem. Just checking to see if any of you have thoughts on how to troubleshoot this.

Appreciate the responses.

Regards,

Shahzad Lateef
2003 Marathon H3-45, DS