Zone 2 temperature sensor?

[jfaberna]

In Florida it is getting warm enough to let me play with the A/C units and test them out. The system has been working both the Zone 1 main unit that is located over the rear of the coach and Zone 2 over the bedroom at the front.

However, yesterday, I was trying to cool down the front bedroom a little and the A/C would never come on. I started checking things out and noticed that the Inside temp when I was on Zone 2 read 52-54 degs. The Zone 1 inside temp was 75 and outside it was in the 70's. Just for testing I put Zone 2 on Fan only and let it run, then noticed the Zone 1 inside temp was back to normal at 74. So I set the Zone 2 A/C target to be 71 and it came on for a while then stopped. Now the Zone 2 inside temp is back to 52-54 and the A/C will not run.

Zone 1 continues to work fine for both Furnace and A/C.

It's a good thing I don't really need A/C yet, but I need to get this fixed before summer. Obviously, it's the Zone 2 temp sensor or a connection from it to the thermostat.

Any idea where the Zone 2 sensor is? I'm guessing the Zone 1 is in the Dometic CCC2 Thermostat.

[HOOK]

There is an extrusion on the ceiling . It is round and 1 1/2 ins in dia. Looks like a pointed hat. That is your area 2 sensor. It is in the bedroom.

[WaltBennett]

We don't have a second AC, but Larry's right about what the sensor looks like. Ours was wired for two and has the sensor screwed to the ceiling just as he said. It's pretty easy to find, but if you can't, I wonder if they left it in the ceiling plenum next to an AC duct from the rear one, and that's why it's reading so cold. If it were mounted on the ceiling, there's no way it could be getting those temps.

[jfaberna]

Well, I took the cover off the sensor and found the solid state sensor soldered onto the cable going to the electronics board inside the Zone 2 A/C unit. Seems it's just a cable assembly that plugs into a Molex connector in the A/C unit. I also found that if I hold the sensor close to my body I can raise the temperature to a max of 71 degrees. I called Dometic and it sounded like a bad sensor to them also.

This would be a warranty issue that would cost me more in fuel and time than the part, tax, and shipping; about $40. Should I report this to my dealer so he can keep track of the warranty issues. I might be able to get him to get me the part under warranty and let me replace it at home instead of dragging the 5W to him.

Thoughts?

[DQDick]

If it were me, I would place a call to Keystone Customer Service and see if they would pay for a local person to fix it under warranty or what other options they'd approve. They did this for me with another issue. The reason I would be concerned is what if it isn't the sensor but a problem with the AC unit itself in some way. I just always like to cover all the bases and have never had a problem with Keystone when they were my first call.

[jfaberna]

After talking to Tiara, they suggested talking to Keystone as well. I'll do that tomorrow. I can always wait until I get back home in March.

[scott-pati]

I try and do any warranty work myself. It just isn't worth the time to take the rv to the shop. I've called the manufacture and they send the parts free to the door.

Jim, now there's a proud man standing in front his Ram and Montana! New picture I see. It's a good one! We need to have a convoy of us and others with the same setup going down the highway. lol

"If you can't Dodge it, Ram it!"

[TAKPAK]

In our 3725, ours is in the bedroom as well, in the corner. I swear, these guys are definitely not HVAC people. The corner is the worst location for air flow you can get. Side note too, watch which way your diffusers are pointed. Ours was aimed right at the sensor, which, of course, caused the AC to shut down prematurely, thinking the room had cooled down, when it was only that one spot!!!

[jlb27537]

Since you are in Fl. There is probably a mobile RV service tech that comes to the RV park. He can probably get the part and submit a claim to Dometic. Maybe ask the office who is the mobile guy for their park?

I used a mobile guy in Colorado to replace the control board in Zone 1 and here in S Texas used a service to fix the Attwood Furnace. Both agreed to the no service charge deal. Just work on it when you are there doing normal customer pay stuff. No problem.

Unplug the molex plug at the A/C and see what the remote sensor is reading.

OHM reading are listed below

Section C - Components, contíd.
For the specific temperature surrounding the sensor, the
ohms reading should be as follows:
Room Temperature Ohm Reading
Temp Ohms
55#F 11667
60#F 10212
65#F 8959
70#F 7876
75#F 6939
80#F 6126
85#F 5418
90#F 4802
95#F 4264
100#F 3793

The service manual is located here for your reading pleasure, see page 35 of 126.
http://bryantrv.com/docs2/docs/acservice.pdf

I find it is sometimes easier and cheaper to just fix it my self time you pay for fuel and aggravation.

Jim

[jfaberna]

Jim,

I'll ohm it out tomorrow and see if it's the sensor.

Thanks,

Jim A

[MDL]

quote:Originally posted by scott-pati

I try and do any warranty work myself. It just isn't worth the time to take the rv to the shop. I've called the manufacture and they send the parts free to the door.

Jim, now there's a proud man standing in front his Ram and Montana! New picture I see. It's a good one! We need to have a convoy of us and others with the same setup going down the highway. lol

"If you can't Dodge it, Ram it!"

I can't join the 3402 club with my little 3100, but man that rig looks good! I'll just have to follow up and pull in when you guys are all setup and have a drink waiting for us! LOL

Good troubleshooting on the sensor, Jim! I'd also call Keystone and see how they can support you!

[jfaberna]

quote:Originally posted by jlb27537


Unplug the molex plug at the A/C and see what the remote sensor is reading.

OHM reading are listed below

Section C - Components, contíd.
For the specific temperature surrounding the sensor, the
ohms reading should be as follows:
Room Temperature Ohm Reading
Temp Ohms
55#F 11667
60#F 10212
65#F 8959
70#F 7876
75#F 6939
80#F 6126
85#F 5418
90#F 4802
95#F 4264
100#F 3793

Well, I'm reading 6850 for about 73/74 #F so it's not far off. with one data point.

Jim A

[jlb27537]

OK, now we know one thing it is not. Need to study where the resistance is changed to a temp display. In the CCC2 thermostat or in the control board in the Zone 1 unit or Zone 2 unit.

My bet would be the Zone 2 control board.

Isn't Hook there with you? Swap thermostats and see if any change. I'll go read the book.

Jim

[PackerFan]

Jim, Thanks for that link to the site with all of the service manuals. Great resource to have!

Scott

[MDL]

Wow, this is awesome data. I just love this forum!!!

[jlb27537]

Jim, we need a update. Jim

[jfaberna]

Jim,

I have not tested further at this point. One A/C unit is keeping up cool enough and since I'm pulling back home next week, I've made plans to stop by CW in Fayetteville, NC to let them quickly diagnose the problem and order the right part. I can let them look at some other warranty issue while I'm there.

Jim A

[jlb27537]

Thanks, let us know. Jim

[jfaberna]

interesting development today. It's 85 outside today and the Zone 1 A/C is running all the time to maintain 77 inside, because the sun in beating down on the living room slide out windows. So I'm looking at the Dometic CCC2 thermostat and decided to check the inside temp in Zone 2 to see if it's still incorrect and what do you know it's now reading 80. So I put the Zone 2 to Cool and that A/C starts running. It's been cycling most of the afternoon to hold 72. So I figure now that I'm documenting this, it will stop working. I just checked the Zone 2 inside temp and it's 68. So we"ll see. The Zone 1 is still around 75, so having the Zone 2 working is helping. Not sure if I still have a problem with Zone 1, but with Zone 2 being intermittent, is going to make finding the problem a nightmare.

[jfaberna]

Back to having Zone 2 read 52.