Intellitec EMS Problem

dougrainer wrote:

Gau 8 wrote:
Upon further study of the manual, the relays 1-4 are normally open. However, the low voltage relays use the normally closed position to control the ACs. So, if you pull the fuse, both ACs should work.

Only 1 AC is shed controlled. Usually the rear AC. Sorry, pulling the fuse will not allow power to ANY shed controlled appliance. There are only 4 relay's. Where you are mistaken in your reading is the section about COMPRESSOR shedding, NOT the complete AC power. Some AC systems allow the Compressor to NOT have power to come on instead of the Complete power to the AC shut off. That means the fan will still have power to run, but the Intellitec system tells the AC control board to not allow the AC onboard compressor relay to energize and close to allow the compressor to run. As I stated, when an Intellitec system malfunctions, NONE of the shed controlled appliances will operate. Doug

The manual clearly lists relays 5 and 6. It also states that the NC tap is used to INTERRUPT the operation of EACH AC. A NC relay is CLOSED with no power.

To prove my point I just turned both ACs on with 50A shore power. I the pulled the 12V fuse in the control module. BOTH ACs CONTINUED TO OPERATE.

You are a hard man to convince.

??

To prove my point I just turned both ACs on with 50A shore power. I the pulled the 12V fuse in the control module. BOTH ACs CONTINUED TO OPERATE

If the system was malfunctioning, WHY did BOTH AC's come on BEFORE you pulled the fuse? Power down the system (120 and reconnect 120) and see if the AC's operate. Why am I hard to convince? Because I have worked on SCORES of Intellitec 700 and 800 model shed systems over the years and have NEVER had any power to the Shed appliances when it malfunctions. THAT is a common complaint when the Intellitec does malfunction--- it is HOT outside and they cannot get their rear AC to operate. Are you positive the compressor came ON and it was not just the fans operating. As I stated, the Front AC is not affected by the Intellitec shed system. What Year/Brand/Model RV do you have? Doug

From the Manual. Your AC/W/H are NOT low voltage loads

The remainder of the relays, relays 5 and 6, are intended to switch low voltage loads. Relays 5 and 6 are single-pole, doublethrow
relays with all contacts available.

You have a Thor product and I believe they do indeed utilize COMPRESSOR shed which means the AC fans will run regardless of the Intellitec, but the compressors will not come on if the Intellitec is out of the loop. You may have the shed relays fused closed also. I have never seen it,but if you do indeed have complete power to the Roof AC compressor and fan, that is the only way. The LOW voltage shed relay's are for the tstat compressor control thru the roof AC compressor.

If you are a self designated expert on this model 800, why do you state that there are only 4 relays. I am an engineer and have designed electrical circuits and controls.

Before my test, all equipment was operating properly. However, the remote display was alternating between 50 and 30 amp with the ammeter showing 0 while at the 30 display.

On genset, the display alternates between 30 and genset with 0 amps. I have confirmed proper voltage at the breakers and the proper 12v run signal from the genset.
The system is using two high voltage relays for the washer/dryer and the water heater. The breakers to the airs are wired direct.

When the ACs startup you hear the fan start with the compressor starting sound 1 to 2 secs later and blowing cold air.

Since I have accounted for all Four of the hi load relays, that only leaves the two low voltage relays fot the two airs. It appears they are setup to interrupt the airs if necessary.

I believe the reason for the shutdown of one of the airs in my original post was due to the outside temp being 65 and the unit icing up. Today it is 78 and both run fine but the remote display is wonky.

Both airs still continue to run when the fuse is pulled. I also tested the relays and all are operating normally.

Over to you.

P.S. My system is set up to shed BOTH ACs if necessary.

1. As I stated, YOUR system uses Compressor shed and NOT shed of complete 120 power to the AC unit, hence the AC's "run". That is a NICE feature of using the 800 system to utilize Compressor shed and leaving complete power to the AC units. THAT info would have been helpful at the start. But if the 800 has a major malfunction, the Compressors will not come on. You CAN make them come on if the system malfunctions by disconnecting BOTH yellow wires at each AC at the AC control board accessed thru the air filter grill
2. YES, I AM a EXPERT, NOT self professed. I have been working on and FIXING RV's for 35 years now. Despite what some Engineers think, they are NOT experts at ALL things. I AM an expert and know MORE about the 800 system than you will ever know.
2. Lets get back to your original problem, IF all wires are secure and no corrosion, the fact that your system remote was going bonkers, shows the Main control board is malfunctioning.
3. Your system (roof AC) CANNOT ice up despite any temp. They have a freeze Thermister in each Evaporator that prevents that despite ANYTHING that could cause Ice build up. But, as an Engineer, you knew that. Sorry, you did NOT know that. So, you are not as smart as you think:B
4. As I stated, when you have compressor shed the systems ARE designed to shed either or both compressors instead of the 120 power. But if complete power shed they only shed the rear AC unit power.
5. The 800 system has extra design parameters that can include compressor shed. Very few RV makers utilized compressor shed back then.
6. You probably need a new 800 control module. Have you check for 12 volt signal at the Genset wire at the quick connect at the module board J2 pin 2? IF you have 12 volts on that wire and it does NOT state GEN on the remote panel, then the module is defective.
7. Last, curb you sarcasm, I am an expert and trying to help you. YOU posted asking questions because you obviously do NOT know what you are doing. YOU keep changing the parameters and scope of the problem, and I have to catch up. Doug

You sir are full of yourself and wasting my time. You accuse me of sarcasm yet slander all engineers. Who do you think designed this system. It was not an RV repairman. Please ignore my posts in the future.

For everyone else, after digging in the manuals I see that my dometic ACs have a dedicated load shedding feature that allows the EMS to disable the unit. This is two wires that are routed to the normally open contacts of the relay. This means that the two wires must be connected for the load shed to function. This also means that the EMS must close the relay. If you simply pull the connector or the fuse, no load shedding occurs. This explains why my ACs continued to run after I pulled the control board fuse. This load shedding can be for one or both of the ACs contrary to some "expert" opinions. My 40 years as an engineer trumps his 35 as a technician.

I am going to permanently remove this Intellitec junk and buy a remote display for the Progressive HW50c I already have. That way, if I have to run on less than a 50A service, I can monitor my own usage and do my own load shedding.