Yes, we have found that too. From online research it's and overheating issue. We were running it with the compartment door open. We did not have the cover on the front off.I checked my 7 page Onan 5.5 trouble code PDF and for my model there is no code 33....it jumps from code 32 to 35.
Either you miscounted the blinks or my PDF doesn't cover your exact model for proper diagnosis.
Our temps were high yesterday, but not that high. Worried since we have a trip planned next week. We don't need the generator when we get there but would like to run it off and on traveling to keep it comfortable in the camper.Here is one explanation of a code 33:
How to Fix Fault Code 33 on Onan Generator? (Error Solved!)
Under certain conditions, your Cummins Onan generator may show the fault code 33 after shutting down by itself, by blinking the status LED on the control switch 3 times followedwww.rvandplaya.com
Here is another:
Fixing Onan Generator Fault Code 33 (What Does It Mean?)
This code seems to be missing from the manual as well. The reason for that omission is that the problem is an uncontrolled shutdown due to overheating.thecampingadvisor.com
Everything I have read about code 33 is related to overheat condition. I have seen an article where the air-cool does not have a code 33, as stated.
Back in April a park we were at in Palm Springs, had an electrical issue. We were on/off generator power from Wednesday to Saturday, and the temps was around 105. The way I prevented the overheating was I left the bay door open and pulled the cover off the generator for better air flow.
Great, glad draining a little amount of oil out that help it out.Just an update. My husband read where if the oil is completely full that may be causing the problem. He drained a little. Just returning from a trip to Texas it ran great in 115 heat.