Samsung EH035CAV mini split, 101 communication error

zimmerdale

I have a Samsung mini split that has worked great for three years. It is the slim concealed duct version with a wired controller / thermostat. A few weeks ago the unit was not running on a hot day, and the controller displayed an error code of 101, which is listed as a 1 minute time out communication error. It was working great one day and not at all the next.

My local reputable HVAC service has been working on this for over three weeks now, with no success. I was present during each visit and repair attempt.

First, they called Samsung tech support and we worked through a diagnostic process of checking line voltages, integrity of the communication wires, blinking LEDs, etc. Then we disconnected several things from the outside PCB and checked something. The Samsung tech said it was definitely the outside control board. The board was ordered.

A week later, the outside board arrived, we installed it, restarted the unit, and a minute later got the same error code.

He called Samsung tech support again, we went through another series of diagnostic processes, and the tech said it was definitely the inside control board. The board was ordered.

A week later, the inside board arrived, we installed it, restarted the unit, and a minute later got the same error code.

Both the local HVAC tech and I were getting more than a little perturbed at this point. He called Samsung tech support for the third time, and the guy immediately claimed it was because we forgot the "thermo-grease." It quickly became clear that he didn't know what he was talking about. After about 2 hours on the phone with him, and lots of back and forth until he understood what we were talking about, he stated that the problem was most likely a programming error on the NEW inside control board that we had just installed. He told us we had to order another inside board. He couldn't explain why or how he thought this, but insisted that was the problem and there was no way to test or verify this.

By this point in the ordeal, my local HVAC tech had also attempted to verify that Samsung would back their tech support and either accept returns of the boards that were apparently unnecessary, or refund us for the cost of the unnecessary or bad boards they had sent. Samsung and/or the distributor he was dealing with said they would not accept any returns and would not refund my money. I decided to stop at this point and try to figure out my options.

If you're still reading, thanks! I now have a non-working mini split with new indoor and outdoor main control boards, a large bill for non-existent repairs, and no idea where to go from here. Can anyone help me out?!

Notes: I'm a small time, tech savvy, remodeling carpenter. I ordered and installed this mini split myself to save money on my own home. I believe that makes me ineligible for their warranty. The unit is dated 2012, but I installed in 2013. Installation was simple and the unit worked perfectly for three years. I have some experience with electronics--I can test and replace capacitors, fix cracked solder joints, etc.

Is there any way to run some more specific diagnostics on this unit to figure out the problem? Is there any way to, at a minimum, convince Samsung or the distributor to take back the parts that they told me I needed but which I apparently don't?

Any other helpful advice?

Thanks for your time,
Jason
Newton, Kansas

Harvey Ramer

Have you checked the wiring integrity? Any high voltage anywhere close creating crosstalk on the communication wires?

zimmerdale

Yes, wiring integrity was checked and verified by the tech.

My HVAC tech also mentioned high voltage interference, but then discounted that idea once he knew the unit had worked fine for three years. Do you think that is an issue that could develop suddenly like this, when there was no problem for several years?

My communication and power are run close to each other, so it may be worth a look to eliminate that as a possibility. Does aluminum flex conduit provide any shielding?

Thanks for your response,
Jason

Paul S_3

was shielded wire used??? we use shielded 14/4 stranded not solid wiring....solid wiring can cause communication issues.

zimmerdale

The instructions that came with this unit were very confusing and poorly translated from the Korean. This unit uses two wires for communication. They call for .75mm2 wire (which would be between 18 & 19 gauge, according to the chart I looked at).

I used 16-2 stranded and shielded wire.

Thanks,
Jason

R Mannino

I'm with Harvey, run some temporary wiring and see if it works.

BobC

Also make sure the ground is solid, a loose ground can cause all kinds of problems.

Bob

Harvey Ramer

Just to give you an idea. An unshielded cable running in parallel and immediately beside a high voltage cable (romex), for 15 - 20' picks up about 5 volts.

Also check the back side of the terminal blocks in both the indoor and outdoor unit. Any blocks have even the slightest corrosion present? This mostly happens in wet environments, but I have seen a micro film coating of minerals and corrosion creating a conductive path between a terminal and equipment ground. Usually not a big deal till your working with sensitive electronics. Check continuity between every terminal and ground. The reading should be infinite.

Might as well check the continuity on the communication cable as well. The resistance should be almost as low as when you put the 2 probes together. Every conductor should be the same.

Check any cable fasteners (staples). If they are 2 tight, it can cause intermittent problems.

Is the cable protected from the weather, namely sunlight, in all areas. Sunlight can crack a cables sheathing, allowing moisture the enter the inner jacket and set up intermittent conductive paths.


I know you said they checked the wiring. But did they REALLY check it?

All that I mentioned I have had the pleasure of troubleshooting and fixing.

zimmerdale

Thanks, Harvey, for your comments. I will spend some time checking over the things you point out. I will probably run a separate, temporary communication line first to see if that solves the problem, and if it does, I'll start working to find the fault.

I've had to do some similar kinds of detective work on my old Volvos, which also tend to have strange electrical faults. I've found that DeoxIT spray is very helpful in cleaning contact points and making good connections.

It's been very helpful to hear several of you indicate that I'm likely dealing with a wiring issue, not a faulty board issue. I do hope that is the case.

Thanks again,
Jason

Ironman

Did you twist or use wire nuts anywhere in the cable? If so, that could be a problem. Any splices, terminations or connections must be done using butt or stake type connections, not twisting or wire nuts. Somehow, the twisting can cause communications errors.

SWEI

Wow -- I had no idea they were that fussy. That tends to indicate substandard engineering either of the protocol (insufficient forward error correction) or the implementation (most likely the input stage and/or power supply decoupling.)

We use unshielded 18/4 CL3P (dual marked as CMP) on the Fujitsus and have had no issues. OD is only 3/16" which makes routing really easy. We regularly pull it in the same conduit with other electrical circuits for 10-12 feet. It fits (along with with three #14's) in a 1/2" Carflex whip making for a neat outdoor unit installation.

On commercial jobs where there are a lot of TRIAC dimmers and switching supplies, we use a dedicated run of 1/2" EMT to provide shielding.

zimmerdale

No luck so far.

Over the last week I've checked every connection and run new communication wire between units and between the indoor unit and the wired controller. I can get different error codes if I disconnect things or change the system addresses, but I still can't get rid of the original error code.

Talking to Samsung HVAC tech support, I asked them to start from the beginning again. This time, when I gave them the error code, the tech said it meant an indoor sensor fault. What? I ordered the $10 thermistor assembly and installed it this morning. Same error code. I'm convinced they're just guessing.

I'm getting conflicting reports on my error code. It flashes alternately:

Er 101
Ad 1F

The first time we talked to tech support, they said a 101 code is a communication error. I can find that in the service manual: "Indoor unit Communication Error." Follow-up measures are to change indoor and outdoor boards, which we did.

This latest time they said the alternating codes indicate a sensor fault. They pointed out the page in the Wired Remote Control installation manual that references Er--A* codes. (I have a total of five manuals for this unit, and while there's overlap sometimes, they don't always seem to agree, and none of them covers everything). The code explanation they referred to is: "EVE IN sensor separation error of the indoor unit."

Nothing changed when I installed the new sensors (air temp sensor and coil temp sensor). But when I started the unit with the sensors unplugged (as a test), I got a "Er 121/Ad 1F" error code. This seems to correspond with a 121 code: "Indoor Temp. Sensor (OPEN/SHORT ERROR)."

In one of the error code lists, it indicates that "Er" means: "Error of setting option for wired remote controller COM2."

When I search for the "Er 101 Ad 1F" error code on Google, the only hits I get are in Spanish. They seem to indicate that this error code happened for them after a power blackout. We had a series of large thunderstorms go through the area, so maybe this is all a result of lightning issues or a power outage?

I'm at a loss.

Anyone have any more ideas before I scrap this system and drop $3300 on a new Fujitsu system?

Harvey Ramer

A lightening strike will definitely take out the inverter board.

I am sorry, I don't have much more to offer on the Samsung product.

ratio

The manual I found for that unit lists diagnostic LEDs as well, what do they indicate? Same thing? Were there any power/lightning events right around the time it stopped working? Power company crews "fixing"things? It certainly sounds like nearly everything has been ruled out, which does point back to a bad board. It's conceivable that the indoor board failed in such a way that it toasted the new outdoor board before it was itself replaced; I have never seen that happen in real life.

Astonishingly, the manual I linked to above gives enough detail to allow component-level repairs to be (tediously) made, although firmware doesn't seem to be included. Another check might be to scope the data bus & see if communication is present, but an oscilloscope might not be in your tool box. A multimeter should give you enough information to hazard a guess-- voltage fluctuations between two or three distinct points is almost certainly serial comms. Check the power supply at the outdoor unit, if perhaps the AC reactor were damaged it might be letting enough noise through to the digital board that it's inhibiting reliable communications.

There a checkout procedure for comm issues starting on page 140. It basically says check that everything is plugged in right, then replace either both boards or the outdoor board. Check for blown fuses. Did the replacement boards come populated with fuses?

When you checked the wiring to the indoor unit, did you use a megger? I've come across intermittent wiring faults that showed clear with a multimeter, it took the high voltage of a megger to prove it was failing.

Welcome to the wonderful world of highly efficient electronic devices!

zimmerdale

ratio said:

The manual I found for that unit lists diagnostic LEDs as well, what do they indicate? Same thing?"

That is one of the manuals I have. The exterior unit diagnostic lights indicate "1min. Time out Communication" (p 3-4, Table 3-2, Number 14).

There are also three lights on the indoor unit, but I can't find a chart that corresponds to those. Everything either refers to the ductless indoor unit (mine is the slim duct) or the wired controller.

ratio said:

Were there any power/lightning events right around the time it stopped working?

I don't remember the exact day that the error code showed up (it was now close to a month ago), but we did have a couple weeks of almost daily lightning/thunder storms rolling through. It is very possible lightning is the cause.

ratio said:

Check for blown fuses. Did the replacement boards come populated with fuses?

The fuses in both boards checked out in my initial testing, and both new boards also came with new fuses.

ratio said:

Check the power supply at the outdoor unit, if perhaps the AC reactor were damaged it might be letting enough noise through to the digital board that it's inhibiting reliable communications.

The initial round of Samsung tech-guided testing included testing for correct voltages at several places on the outdoor unit. Are you talking about something more extensive?

ratio said:

When you checked the wiring to the indoor unit, did you use a megger? I've come across intermittent wiring faults that showed clear with a multimeter, it took the high voltage of a megger to prove it was failing.

I'm afraid this is above my paygrade. Are you talking about the communication wiring between the two units? The HVAC tech did a basic continuity test of the communication wires, and I repeated that test later and also checked for any grounding issues. I also tried running new communication wires between the units and between the indoor unit and wired controller. I was hoping that these things all together would eliminate the possibility of communication wiring issues.

ratio said:

Welcome to the wonderful world of highly efficient electronic devices!

Don't I know it.

headmaster

Hi Guys I have a Samsung 24 000 BTU and was work 2 years good, but now 101 error (1 min Time out Communication). Ok, I check all wire connection, inside and outside, Check voltage, ground, fuses, but the same. I open the main board and push all connectors, wire, nothing. Tomorrow I think run new 2 wire only for communication, but for supply I want to use the same. All together we try to find a problem.

kernowgav

Hi guys, I'm researching for a similar problem on a Samsung AQV24 - Zimmerdale, did you get anywhere with fixing this issue?

zimmerdale

kernowgav, I never solved the problem. After many, many calls to Samsung tech support, 3-4 visits from a local reputable tech, replacing all the boards on the entire unit, double checking all the wiring and power specs, replacing the communication cable, etc. with no results, I gave up. I have no idea what's wrong with the unit.

I had a local firm install a Fujitsu unit that they had installed many times in the area. They spoke highly of the unit's reliability and their experiences with factory support.

Sorry to hear you're experiencing the same problems.

Timsfla

Hello SAME ISSUES HERE with a senville 36,000 dual mini split. They even sent a new outside unit and one inside unit and the E1 error was still there. But the new inner unit was installed before the outside unit. Only 3 months old.
I am trying new com wires this weekend that are stranded but not shielded. Orgininal are solid. Not sure how important the shielding is, but will run thru window for test.
Tech support does not know. Very helpfull but just do not know. they sent a new inner and outer board for the NEW replacement inner head and outer unit. STILl get E1.
SO the new FUJITSU unit solved the issue? Thoinking of doing the same. but want to make sure no underground shorts first.

donaldburgess

installed 3 matching 24,000 Fedders in 3 separate apts, all comm. wires in same raceway. after just over a year Apt A failed with communication Error code(Manufacturer went dark one month after we made the purchase! ) Local trusted HVAC ran temp separate communication wires, no help and he was done saying with out tech support or parts he can only recommend new install!! But it IS NEW! I will put a scope on operational unit and generate that waveform and amplitude for each of the three motors and switch full on only wired to an old style wall thermostat.
If I had the chance.... I would have bought all of the indoor and outdoor boards I could have found and paid almost anything for them! What else could it be right? the other two units are humming along flawlessly since '15, let me know if anyone ever solved!!

NY_Rob

donaldburgess said:

...I will put a scope on operational unit and generate that waveform and amplitude for each of the three motors and switch full on only wired to an old style wall thermostat.

Well that is an interesting solution.

Just curious... How will you generate the waveform? Arduino, Raspberry Pi, 555 timer, etc???