Jim McGarvie

Thanks, Richard. I already have that manual. You may all know that the Dometic Penguin AC's come with four wire RJ-11 connectors to connect the AC's to the normal Dometic thermostats, but our Dometic AC doesn't know that. It did NOT come with four-wire RJ-11 connectors, but with a cable containing six conductors. There is no adapter. I know you guys are all very knowledgeable and experienced. The only thing I can think of to explain this apparent contradiction is that maybe our AC is NOT a 600315.321. I was relying upon the parts list that came with the coach from the factory. Maybe it is some other Dometic DuoTherm? I have attached a picture showing the baseplate of the Honeywell thermostat showing the wiring connections. Only four of the six wires are used; the other two are taped and stuffed back into the wall.

Thanks for the link, Richard. That should be helpful. I can't speak for "normally", but I can tell you unequivocally that when we picked up this 2002 coach at the Monaco factory in August of 2001, it had a thermostat with no buttons whatsoever. I threw it away when it died a couple of years ago so I can't send a picture of it, but I have attached one of the bedroom A/C thermostat. The original front thermostat was identical but for a switch for heat for the furnace. Nary a button in sight. For those of you who have asked how I wired this thermostat, I have attached a diagram I found somewhere online. I think it is pretty clear, and worked fine. The only way in which I varied from this is I did not add a switch for hi fan. I just wired it to always use hi fan.

The thermostat is a Honeywell RTH7600D. I use it for both heating and cooling, but I only use the programming feature for heating. I'm sure it would work fine for cooling as well, just haven't found the need.

Thanks for the input, Ray. But I guess since you are recommending I replace my thermostat you must be assuming there is something wrong with our current one. Can I ask what makes you think that? Because I really don't want to lose the programming capability if I can help it. I don't use it for cooling, but for heating it follows a schedule keeping the interior at 72 degrees until 9 pm, then letting it drop to 55 (which it very seldom does) until about 1/2 hour before I usually get up in the morning, then warming it back up to 72 by the time I get up. I don't have a reason to believe there is some reason a programmable residential thermostat shouldn't work properly with our particular A/C, primarily because it worked perfectly for two years. What am I missing?

Thanks for your confidence in me, but I'm not sure I know how it works. I think the batteries in the thermostat are primarily for display and memory. The thermostat it is replacing is really only a switch, right?

Thanks for the reply, Vito, but our 2002 (made in 2001) coach never had any buttons. It was a really old fashioned thermostat, just a couple of switches and a rheostat. Our residential thermostat worked perfectly, for the furnace and for the A/C, for two years.

Our front roof A/C is a Dometic 600315.321. Intermittently (don't we all hate that word?) the compressor will come on without the fan. I can switch the fan from Auto to On on the thermostat and solve the problem temporarily. Or I can turn off the circuit breaker for the front A/C or remove the thermostat from the wall plate, either of which, of course, stops the compressor and the fan. Sometimes when it is acting up I will remove the thermostat for a while, and when I plug it back in the A/C comes on normally. The thermostat is a residential programmable Honeywell. When this same issue occurred last month my troubleshooting led me to believe the problem was in the thermostat, so I replaced it with a new one of the identical model. That seemed to have solved the problem for a while, then yesterday it returned to its previous behavior. Any and all suggestions welcome. Thanks. Jim

Thanks David.

Thanks for the clarification, David. I should have realized the Deutsch connector at the rear of the coach was a type of OBD. How does one go about determining whether a port is J1939 or J1708?

I'm fairly confident our coach does not have OBD. The only diagnostics port I'm aware of is the only one mentioned in manual for our coach: the round 9-pin (J1939) port with the word "ENGINE" at the rear below the oil dipstick. I have spent way too many hours under the dashboard, and have never found a port there. I would love to be proved wrong, but.... Or is it possible to plug a Bluetooth adapter into that for a scan tool up front?

Thanks, David, that's a good thought. Any particular recommendations? Any recommendations? How do they interface with the vehicle? Our Cummins ISB 5.9 has no OBD port.

Ha! I do that too! But not while I'm driving. I often check the trip meter, which I reset when I fill the tank, to get a feel for how much further we can go before refueling.

This has been an issue since we brought the coach home from the factory 20 years ago. It probably hasn't gotten worse, but my eyesight has. Has anyone experienced this problem and found a solution? Can't make it any larger, but a stronger backlight might help. Thanks. Jim

Spot on, Rick. Our coach does not have air leveling, and deflating the air bags deflates the entire system, tank and all. And as you point out in your last sentence, within a couple of days our bags are fully deflated no matter what we do.

Richard, Nope, no switch to dump just the bags, only the entire system, bags and tank. I would love to be able to just dump the bags. And yes, we have four bags.

My system is different: I don't have air bag leveling, but I have to hold the Air Dump switch on the dash as I am going in and out, and eventually the air parking brake sets itself. So I release the air switch until I can release the parking brake and proceed further. Lather, rinse, repeat. But I am quick enough now I can usually drive in or out on one cycle of the procedure.

Our hangar ceiling is also exactly 12' high and I have to do the same thing. I am waiting for the day I forget! I wish I could figure out a way to dump just the bags (I have to empty the tank too) and turn off the air to the bags. It could probably be done but the plumbing is complicated (to this geezer, anyway).

Thanks, Richard, but that doesn't work. The fan would stop, but not the compressor. That's why I suspect a stuck relay on the A/C control board. Since I suspect it is not good for the compressor to run without the fan, I resort to tripping the breaker. When we want to run the A/C I turn the circuit breaker back on (which starts the compressor) and then use the thermostat to turn on the fan.

Disregard. Problem solved. I found a post on IRV2 which said all circuit breakers must be on for the EMS panel to function normally. I had turned off the circuit breaker for the front A/C because it is running continuously (another issue; stuck relay maybe?). I turned that breaker back on and the EMS panel is now indicating correctly.

We have an Intellitec 50 AMP Smart Energy Management System (EMS) Model 750. We are currently plugged into a good (verified by Progressive PT50C) 30A receptacle. At one point our EMS indicated a 50A source rather than 30. I started the generator and the panel correctly indicated "GEN SET", but when I killed the gennie it went back to indicating 50A. I was able to reset it by killing all power (AC and DC), waiting a bit, then re-establishing power. It indicated normally for a day or so, then went back to the 50A indication. I tried the reset procedure again, twice, but this time it didn't help. So my questions are, what causes this malfunction, and how can I fix it? Do I need a new control board? Thanks. Jim

Thanks to those that responded. I have to admit, though, that even as a fairly capable DIY mechanic the job sounds a bit more daunting than I expected. I.e., I did not anticipate the need to remove the radiator etc. I think this is beyond my desire, if not my skill set, and we don't have time before our next trip to have it accomplished. I do agree, though, with the suggested work while the radiator is removed. But for this trip I will just carry a new pump, tensioner and belt, JIC. The leak is so small at this point there is no coolant on the floor.

My mechanic was trouble-shooting something else and noticed coolant leaking from the water pump weep hole. I think that means I need to replace the pump pretty soon, before the leak reaches the pump bearing. Is this the same pump as on the Dodge pickup with that engine? And how big a job is it to replace in the motorhome application? Thanks. Jim

That is one reason I also have the Progressive EMS.

Hi Chuck, I'm curious about Bill's recommendation. We have both the Hughes Autoformer and the Progressive portable EMS. I installed the Hughes first, after a brown-out in an RV park cost us a TV. But I think the capabilities of the EMS are more important.

I've been using mouse milk for years on the Pacbrake. I use it because we use it on turbocharger wastegates for airplanes, and those get pretty warm too. But I'm a big fan of Tri-Flow so might switch to that.