trailmug

Thanks, exactly what I needed. I was worried it would be one of the solid state outputs on the Kongsberg like the big boy boost switch which blew, I assume due to inadequate diode protection. I can live without the batt boost, but not the condenser fan. 😁

Switch is working OK since the clutch gets power.. thinking there's a relay, fuse, or solid state relay in the mix somewhere that needs attention.

2008 Signature, I've done extensive work on the dash a/c system over the years, but have yet to run into this.. no power to the condenser electric fan when the compressor is engaged. Goes off on high head when parked (obviously, thanks binary switch). This one doesn't have a switch-controlled fan, so I presume it gets its power from either a discrete power relay or the chassis multiplex unit or fuse box in the front pass-through bay. I always assumed it ran off of the clutch relay, but apparently not. Having trouble finding the condenser fan circuit on the wiring diagrams. The cable does appear to go to the front cargo bay, but I thought I'd reach out and see if anybody had knowledge of how it gets power.

Thanks,
Rob

Yes, might as well get the sensor kit, since it's not cheaper than the cover alone.

Though the sensor is just a run-of-the-mill 6.8KOhm thermistor. 😁

Thanks for the update, my preheat pump quit years ago, replaced the pump with the newer style and it died again. I resorted to block heater to start and letting the engine pump pull the heat in from the boiler (still works pretty well). I'll have to check someday and see if the problem is in fact electrical.

I assume D3 is just connected across the pump leads, and is doing flyback protection for the Q18 driving the pump. I'd grab a rectifier diode with at least 150V of reverse voltage tolerance, but otherwise choose anything that fits, say, a 1N4003RLG.

As long as the tire is carrying at or under its single/dual rated load, I'd use the inflation pressure table from the tire manufacturer for the load range / size you have and run it. Our sig runs 120PSI up front cold, which goes to 140+ in summertime mountain runs! Michelin wanted 115 for the same size / load range. The 75 vs 80 will make a small difference in the revs-per-mile, so adjust your mileage/speed expectation/computation.

If I recall correctly, G tires would work with the rear end of our 45' sig.. I tried to source some Toyo M122s for the rear, but couldn't find them locally. Put the M144 H steer tires all around as our local tire dealer stocked them 4 at a time. Very happy with them, as others seem to be. 5 years (outside covered storage), no checking, stay perfectly inflated over winter.

My understanding is you can also use 11R22.5 truck tires in place of 295/75/22.5.

Found my scope pics from 2021.. nerd alert....

Here's the pogo stick that snubber is filtering:

Inverter 1700W load:

Inverter no load:

Digital TV reception is a pain in the rear.. I think I'd need a toner if I was going to try to hook up the coax to the roof antenna (which has a stripped motor anyway). It's impossible to get a good "set-top" HDTV antenna, I live 6 miles from the antenna farm and I still need a Channel Master in the attic!

It's an original Magnum PS, yeah.. I hooked up a scope to it one time because I was curious, and the quality of the waveform seems to vary a lot with load. I think it would take a pretty expensive filter to smooth out the steps from the FETs.. or mine is just old and has dried up capacitors. For the sake of novel discussion, I did place a car audio 1 farad capacitor across its input with some heavy wire to see if I could cut down on the light dimmers flickering while running the microwave on battery (which I wouldn't generally recommend, but I try not to start up the genset to nuke a hot dog or make a pot of coffee 🙂 ). It helped some, but I'm glad I used heavy wire.. if memory serves, ripple current was as much as 60A. 😮

I wish RV manufacturers used 24V house electrical systems.. It would cut down on a lot of silliness.

Paying a visit to the bus for some maintenance and thought I would post my experiences with the Sharp Aquos TV in the bedroom in our sig. It's an old 720p LCD, but the cabinetry is nicely built around the exact shape of that television, and I was finding it difficult to find a TV that would even fit in the hole, if I even wanted to try to fashion up some trim. I'm not much for woodworking, so I figured I would go for broke and try to fix it.

It works out that there's a common failure in the Delta power supply board used in these. It uses a single zener diode as a snubber for the standby power supply transformer, which is prone to failing short. The part number on the PCB is D7907. I replaced this once only to have it fail again. Maybe it doesn't like eating the stepped sine wave of the inverter, who knows.. The reference design for the SMPS IC is to use an RC snubber, and the board had solder pads for the passive parts, so I soldered them in. It's been working nicely for a year and a half. Here's the replacement parts list, and a photo of the repair, in case anyone ends up wanting to tackle the same issue.. not a bad deal for less than $1 in parts. 😁

R7917 and R7918: 200kOhm 1/8 watt
C7913: 2200pF 1kV Vishay Series F, PN: F222K53Y5RN63K7R
D7907: remove

If memory serves, this power supply has a "hot chassis," so keep your hands to yourself if you have it plugged in with the case off.

I'm wondering a the wrong label(s) were applied to the multiplex output module(s). Also perhaps the multi-speed fan wires got mixed up. We had a couple of low voltage mistakes on our coach, like the driver's side living area reading lights having their ground connected to the window shade output module.. they'd turn off when lowering the shades 😎

Also it sounds like possibly the wire to the multiplex input module that tells it the furnace is called isn't right.. did it ever work correctly? 

Roger that, page 131 of that PDF has the multiplex input/output modules. My bit about the dash air relay might be irrelevant; wasn't able to find the Aqua Hot schedmatic in that download.

Ours is like yours, multiplex button in kitchen that does off/low/med/high. Only is supposed to blow (and light only illuminates) when zone 1 furnace is calling from the rooftop unit. Also I've found that the fan speed can't be adjusted when the fan is not running.

I believe the multiplex signal that lights the galley button LED and commands the fan on comes from the dash HVAC fan relay PINK (GAL A-H BLWR ON-SIGNAL) to the multiplex input module "F" J4-4 (presumably nearby or up in a cabinet overhead). That relay is energized by the #5 FAN wire coming out of the Aqua Hot control panel, which is triggered by the #5THERMO wires from the rooftop unit, presumably subject to some logic in the AH unit like low temp cutout. The fan power itself would be provided by a multiplex output unit that's not on this drawing.

I hope that gets you started, this one might be fun 😑

38071413 (Schematic, Dual Heat Elements, Aqua-hot).pdf

Here's the multplex schematic. Zone 1 fan is driven by 10 CHANNEL OUTPUT MODULE "E", P/S WARDROBE (outputs J2-5, J2-6, J3-1), as you discovered.

38080525 (Schematic, Multi-Plex).pdf

Next visit I pay to the storage facility, I'll try to check out which output LEDs turn on at different fan speeds.

Hey while we're looking at 38071413, can somebody offer me a description or photo of where the galley temperature sensor / thermistor is supposed to be on a >40 ft coach? Ours is not fitted, and Zone 2 has to be set to some wacky temps to make it operate. I assume it was going to be installed on one side or the other of a lunch break, and it's jammed in behind a cabinet fascia somewhere.

I've had this experience. There's a firmware bug on our AH or multiplex where the fans won't come on because of low-temp lockout, even if it's come up to heat using electric. Engaging diesel only for a second (not long even long enough for it to fire) fixes this, and after diesel is turned off, the fans continue to work on electric. Every time I set up the coach for winter electric heat to prevent freezing, I turn on the diesel for just a couple of seconds.

There is a big green connector with low-voltage wires.. maybe 16 of them, that screws into the back of the AH control panel, which is screwed into the plastic fascia on the wet bay, curbside. It's what has the green zone, etc, LEDs on it. I presume that might be the panel you're looking for.

Since we've got a nice searchable thread going, I'll put the rebuild part number for anyone who hates themself (I had a spare on-hand already, valve replacement is a job for future Rob). 😀 It's Asco #302272. Supplyhouse.com has a reasonable price if anyone does.

Bingo, piston returned from vacuum when I pulled the diaphragm off due to plugged weep hole. I think the brass body of the valve is getting galvanic corrosion. Maybe some dielectric unions would help? No, I guess the whole thing is PEX.. 🤔 The steel spring and piston were pretty rusty, despite being 2yr old. Seems like a poor design choice.

34 minutes ago, Harvey Babb said:

You might try a sprinkler valve. Lots cheaper and more available (Lowe's, Home Depot) and they have a manual bypass. While they're made for 24 volt AC I'm pretty sure they'll be ok on 12 volt DC. (They're cheap enough that if it doesn't work out you haven't lost that much.)

 

I like that idea.. used one and three 9V batteries before for a potato cannon with much success. 😀

Our 2008 Signature has an electric fresh tank fill solenoid, which is an Asco Red Hat branded valve. About every 2 years, we end up with a problem where the valve doesn't want to close, which results in the fresh tank overfilling, and the complete inability to pressurize the domestic water system (the AquaJet pump just dumps into the tank until the valve decides to close). I'm getting ready to put my third rebuild kit on it (so I can feed antifreeze into the hot circuit), which replaces everything but the brass base and the electromagnet. Has anyone else struggled with this? Am I missing something? Our house has extremely hard water (>20GPG), so maybe it's just getting jammed with minerals?

Thanks,
Rob

38070806 (Schematic, SCS HVAC).pdf

Here's the relevant schematic.. looks like a second blower motor resistor hard-wired for speed 2, and a relay to take over when the dash system is off.

Coolant will flow through the engine coolant loop and warm up the AH boiler whenever the engine is running. I find that's enough for space heating into the 30s once the engine comes up to temp. The preheat pump will force coolant through the engine when the key is off, but with the block heater, I don't find much of a need for it. I suppose if you were camping off grid it would be a good way to get engine block heat using diesel. My experience is that the preheat pump is prone to failure. Ours was broken, I replaced it, and now the replacement doesn't work. The old pump models aren't available anymore and you have to adapt the plumbing fittings to a new size.. IMO, not worth the hassle.

Our Sig has a second heat exchanger in the dash air vent system for AH, and a pair of boiler lines for it visible on the generator firewall. I'd check the plumbing. 👍

Agreed with all above. On a lot of fittings, you can test fit the o ring by sliding the threads out of the way and making sure it fits snugly into the female fitting, as well as make sure the flange doesn't bottom out with hand pressure. AFAIK, the rings have obtuse metric sizes that are diameter x thickness. If the fittings aren't pitted from moisture, maybe the rings are small? I've always found the sizes I needed in Amazon HNBR kits.