Laredo Electrical Question

sjturbo · 10-08-2014, 06:15 PM

I recently installed an inverter on my 2010 316RL. I tied it to the 15 amp circuit that powers all the outlets , (except the GFI's),and ceiling fan (as far as I can tell). So now the circuit is only connected through the inverter! Situation is that I am plugged into shore power to charge the batteries and when I turned the thermostat switch to fan only it does not turn on. The Air Conditioner compressor turns on when I switch it to that position, but no fan there either. I tried to turn on the fan on the furnace but nothing there either. The air conditioner has its own 120 volt circuit and I assume that the fan is 120 also?. I'm sure that the fan for the furnace is 12v so that may be another issue. One note is that the output of the inverter measures 116 volts. I have not run the ac for likely a year so I wonder if there is a problem not associated with the inverter install. Is the air conditioning fan connection accessible from inside or outside the 5er? Any ideas??

jtyphoid · 10-08-2014, 07:02 PM

The AC fan is indeed 120V. The possibilities that come to mind are: no power to the fan motor, failed capacitor, burned out motor, and failed fan bearings.

I've experienced both a bad capacitor and gummed up bearings with my AC. The fan motor and capacitor are easily accessible by removing the AC shroud up on the roof. It's been a while, but I think that I was able to test power to the fan at a connector on the underside (from inside). This was on a Colman AC.

sjturbo · 10-08-2014, 07:09 PM

Thanks for the quick response jtyphoid! Can I assume that the ac fan is on the same circuit that the compressor is, i.e. the 20 amp circuit breaker for the ac?

**JRTJH** · 10-08-2014, 07:35 PM

The A/C fan and compressor are on the same romex power source supplied by the same circuit breaker. Where it gets a bit "tied in" or "confusing" is when the thermostat comes into play. If your trailer has a wall thermostat that controls the A/C and also controls the furnace, it is a "common link" between the 120Volt and the 12 volt battery supply. The thermostat if set on AUTO will select one or the other and if heat is called for, only the furnace will operate. If A/C is called for, only the A/C will operate. BUT if the thermostat fan switch is set to HIGH or LOW, if heat is called for, the furnace will come on (12VDC) and the A/C fan (120VAC) will come on. If you have the inverter "interconnected" with the circuit breaker panel, you may be backfeeding into the A/C when the thermostat calls for heat. I'd disconnect the 120 volts from the outlet circuit breaker (your inverter connection) and see if the furnace operates properly when heat is called for. If it does, then your wiring is the problem. If it doesn't, then you'll need to troubleshoot further.

mguay · 10-09-2014, 03:11 AM

I would disconnect the inverter and see if it works then. If I had to guess I would suspect the problem is in the thermostat itself, just as JRTJH said. If with the inverter disconnected it still doesn't work, then it is time to upgrade the thermostat.
My Coleman one only lasted a couple of years!

sjturbo · 10-09-2014, 05:35 AM

Thanks! The inverter is wired direct to the circuit romex and does not go through the circuit breaker or panel. I have unplugged the inverter and it does not solve the problem. Can I check the thermostat in any way? Can you recommend a replacement thermostat?

**JRTJH** · 10-09-2014, 06:42 AM

Quote:

Originally Posted by sjturbo

Thanks! The inverter is wired direct to the circuit romex and does not go through the circuit breaker or panel. I have unplugged the inverter and it does not solve the problem. Can I check the thermostat in any way? Can you recommend a replacement thermostat?

You haven't said if you have one wall mounted thermostat that controls both the A/C and the furnace or if you have two thermostats (one for furnace, one for A/C) or if you have a wall mounted thermostat for the furnace and ceiling mounted controls for the A/C.

As for getting a replacement, Lowe's or HD both have digital thermostats that work on battery power (12 VDC) and offer improved features over the older "dial/spring" type of thermostat. But, you need to replace what you have with an appropriate new model. Depending on what you currently have, the choices for thermostats would differ. Also, if you buy a replacement at HD or Lowe's you will lose the A/C fan speed capability, it will only operate on high or on low, not switch between the two. If you want that capability, then you'd need to get an "RV specific thermostat" from an RV dealer. Usually the digital Dometic single zone thermostats are about $40-50, but most dealerships won't have one in stock. There is a modification to the existing wiring/HD thermostat that can be accomplished to have a dual speed capability, but with your troubleshooting, I'd suggest not making more mods until you get the system up and running. So, a new thermostat that you know will work with your RV would probably be wise, but not necessary. Again, your choice.

I still think there's an issue with the way the inverter is wired into the trailer electrical system or an issue with feedback through the furnace, A/C or thermostat. It could be as simple as the voltage drop to the inverter when the furnace comes on (drop in battery voltage) or a demand by the inverter input power (low DC voltage to the furnace/thermostat system) that's causing the issue. Or it could be some other wiring problem as well as a faulty component. BUT: If the systems were functional before the inverter install, I'd suspect that it's the inverter install that is causing the problem, not a "new failure" of a component.

I'd completely disconnect the inverter from the system, rewire the outlets as they were originally installed in the electrical power box. (ie: Put all wiring back like it was originally) Then you can troubleshoot the "original system wiring" and see if it works or not, Once you get that working, then you can start the modification process with the knowledge that the components are, in fact, working as originally wired. If you again get this same failure, you will know it's not the components, it's your modification that is causing the issue.

It's been my experience that an individual component may fail, but not three "malfunctions" (A/C, furnace, thermostat) all at the same time. That kind of multiple failure only occurs with an electrical input surge/disruption(lightening strike, power surge, brown-out, etc), and then you'd usually smell the damage as well as see it. Since there is a modification of the electrical system at the same time as the "3 component failure", I'd suspect it's not the 3 things all went out at the same time.

ADDED: The thermostat works on 12VDC supplied by a fuse on the power distribution panel's 12 volt fuse panel. Even if all the fuses are good, there may be a wire that you knocked off the terminal board when you were changing out the connections on the 120 VAC side. I'd also check to be sure that all the 12 VDC connections are tight, properly wired and that you don't have a broken wire at a terminal. Often solid strand wires will break where they are stripped and connected to terminals. You may have broken a wire when moving the panel to work on it.

Good Luck,

sjturbo · 10-09-2014, 09:17 AM

Ok, somewhat good news. Hooked back to circuit breaker. Checked all fuses (good). Thermostat does work the furnace fan

. Air conditioner compressor still comes on but the fan does not come on! BTW the thermostat controls both furnace and ac. I pulled off the interior ac grill but I need to check the ac schematic, (if I can find one) for wiring ID. So at this point I am led to believe that the wiring of the inverter may be a non issue? I will update as possible.

sjturbo · 10-09-2014, 09:51 AM

Ok, Can anyone help with ID'ing the AC unit on my 2010 Laredo 315RL? I see I don't have any doc's on the ac unit and I would like to try finding a schematic or wiring diagram. The fan spins freely so I don't believe it is the bearings. I would like to check some voltages but would like to check out some docs first. Hope someone can help.

**JRTJH** · 10-09-2014, 10:26 AM

Remove the inside filter cover and use a flashlight to look at the top center portion of the air conditioner. You will see a small data plate with the model number, serial number and a couple of other numbers. The data plate may be covered by tape used to seal between the return air and supply air sides of the plenum. Use the model number on the Dometic website: http://www.dometicmanuals.com/PROD/M...f?Opendatabase

Type in your model number to download the installation/user manuals.

If you can't find them there, then contact Dometic by email at: [email protected]

sjturbo · 10-09-2014, 01:05 PM

Thanks for the location JRTJH. I appears that this is a Coleman AC. I did a quick search but have not located a good web site. This does not surprise me. I will keep looking.

**JRTJH** · 10-09-2014, 01:21 PM

How "unlucky" can you get ?????

If you can't locate the model/serial number tag on the inside, go on the roof, use a flashlight and you can see the rooftop data plate located on the side of the chassis, usually right next to the evaporator mounting on the roadside of the air conditioner.

Try these links for the information manuals:

http://www.rvcomfort.com/rvp/products/rooftop/index.php

http://www.rvcomfort.com/rvp/product...an_mach3_1.php "Generic" documentation and installation instructions are at the bottom of the page

http://www.rvcomfort.com/rvp/tech_info/ This is the link for documentation search for model specific literature.

Good Luck

sjturbo · 10-09-2014, 04:35 PM

Thanks again JRTJH! Appears that Airxcel is Coleman in disguise. I found one of the web sites that lets you enter your model # however mine is no longer made and documentation is not available. A phone call got me a recording something to the effect that only our service centers have the capability to understand such dangerous things a high voltage so contact them. Anyway I will try to determine something from the generic diagrams.

**JRTJH** · 10-09-2014, 04:40 PM

Post the model number and any other significant data you found on the unit, maybe someone has a copy of the installation/owner's manual in PDF format they can post or link for you.

mguay · 10-10-2014, 02:56 AM

The thermostat is a Coleman as well. On the back of it...if it is like mine was...the terminals will be marked as to what they control. If you jump the fan to ground it should come on. If not...then it is in the ac.

I swapped out the thermostat after the first year. We found the temp swing/variation of when it goes on/off was never constant. I grabbed a Honneywell one at HD for around 30bucks that is digital. The directions that came with it were pretty clear and with the terminals all marked on the back of the Coleman one, it was easy to install.

sjturbo · 10-10-2014, 03:07 PM

JRTJH, I created a separate thread with the model # for the Coleman (8335D7564) for more visibility.
mguay, My thermostat (AP7862?) has colors listed and W1-W6 for each wire. Unfortunately no functions are listed.
However, the thermostat cable connections at AC unit have the same color wiring and the green is attached to GH, and the white to GL? I am continuing my quest for a solution.

sjturbo · 10-10-2014, 03:20 PM

Search found Thermostat on ebay that listed the wiring as:
Green Hi Fan
Grey Low Fan
Yellow Compressor
Red +12dc
Blue -12dc
White Heat.

That may help somewhat. Since none are listed as ground, I'm not sure what to jump the fan to, (-12dc, would that be common)?

sjturbo · 10-10-2014, 03:54 PM

OK! I have some information. Thanks JRTJH! listed some web sites that have some generic diagrams and a flow chart for troubleshooting No High Fan. This may be a good start. I will keep you posted.

sjturbo · 10-17-2014, 05:22 PM

I believe I've diagnosed my AC problem (no high/low fan) down to the AC Control Box circuit board. Now my big question is where can I find a replacement board? I was unable to find anything on the Coleman web site and it is to late to call? The circuit board is made by ICM Controls and has two numbers 7834-3, maybe the circuit board number and 833B327, maybe the unit #. Any idea's?
Thanks!

**JRTJH** · 10-17-2014, 08:09 PM

If you have an Appliance Parts store (APA) near you, give them a call. Many times parts for RV air conditioners are interchangeable with home/window units. They may have a reference number conversion to something they stock. I'll assure you it will be half the price of any RV dealer.

You may also like: