Ready To Throw This ProHeat Through A Window...

If I could rip it off the truck, I would. Unless I can get some useful suggestions here. I have an '07 KW T600 with a Gen 4 ProHeat APU. Let me state what HAS gone wrong with it so we don't suggest things that are fixed. A/C didn't work summer before last, but I dealt with it. This past summer, I couldn't do it again. Had the A/C repaired. Unlike I commonly read in here, it had nothing to do with leaking freon or A/C lines. I don't recall what exactly the part was that the Carrier dealer replaced, but it was a small electrical component that attached to the unit under the bunk. They fixed it and the A/C works...Not great, but good enough for me. Now here comes the winter. The first time I got into weather that was below 60, I'll have the APU set to comfort monitor--->73 degrees. It'll click on as soon as I shut the key off, run for 2-3 minutes and then shut off. The screen reads "HVAC BREAKER. PRESS ESC/RESET". So, I do. 2-3 minutes later, it shuts off again. Lived with this for about a week. Finally broke down and bought a tiny ceramic space heater to plug into the electrical outlet under the bunk. The APU will run, keep the batteries charged and allow me to operate the space heater. Until this morning. Woke up to 32 degrees in the sleeper. APU was running but the space heater was not. Hmm...From old habits, I automatically press the reset button on the APU control panel to no avail. Then I press the heat button on the APU control panel. That's not working either. Same with the A/C button. Now I'm wide awake as I can't figure out what's going on. I notice the APU is running, as previously stated, and idling normal EXCEPT for a funky noise I'm hearing. Sounds almost like empty soup cans being dragged on pavement. Turn the APU off, noise goes away. Start it back up, noise returns. And still no electric power or HVAC power. Got dressed and went outside, took off the APU cover checked the fluid, looked to the little lights inside to see if I was missing something...Nothing. Everything was as it should be. Until I started it back up and that God awful noise came back. It is coming from the APU engine somewhere. Anybody else have one, if not both of these problems? I'd rather fix it myself as depending on Werner to make sure it's done right will cost me a week of sitting around. Any advice is appreciated. Any ideas are better than none at this point. Thank ya much.

 

I did go out and check the belts...Both were on. They do however look loose. I was a mechanic before I became a driver, and I know how belts should look when the engine is running. They definitely appear loose to me. And the noise...Seems like when I put my ear closer to it, it almost sounded as if it was coming from the alternator itself. Did a visual inspection as best I could of that and found no loose bolts, wires or the like. I'm beginning to wonder if a loose belt on the alternator could disrupt the pulley, causing the noise and lowering the electrical output. Have you heard of such a thing?

 

I agree. There's some things even I won't mess around with, and APUs are one of them unless I'm certain of what it is and have the proper tools for the job. The loose belt theory is sounding more plausible especially now that the APU won't even start up. It cranks but won't turn over now. Loose belt(s) could cause that, I'm sure. Looks like there will be a trip to the Carrier dealer tomorrow.

 

I second that # never using a ProHeat/Carrier again. The thing has let me down and let me roast in the summer and freeze in the winter. I've been tinkering with it since I woke up to my deep freeze. Got it to start back up and it sounds terrible. Idles fine, save for that pulse-stopping noise. Took a closer look and listened more keenly and it seems to be coming from the crankshaft(?) or balancer pulley. The belt has absolutely zero tension there, so I'm guessing the lack of tension is causing the balancer to stray a bit and create that grinding noise. Maybe even the bearings are bad? I've read about that issue on this unit elsewhere (can't recall where), and at 10,432 hours on the APU clock, it seems entirely plausible now. I appreciate all the feedback. It's helping me eliminate implausible ideas and showing me more likely causes. Thanks, ya'll.