Original Penguin AC/Heat Pump control board replacement

[roscott]

First time poster....please excuse the length. I have a 2004 Concourse that was originally owned by my parents...but is now under my care. I am not unfamiliar with RVs as I've had a Diesel Pusher as well as other Class Cs in the past. As I was testing the systems to makes sure everything was in working order, I turned on the AC...it came on for a few seconds then shut off. After that, whenever the house batteries are on or the generator is running, the furnace fan blows and cannot be turned off. The AC does not work and the thermostat looks fine when on, but has no affect on the system no matter if I change the settings. I went on top of the unit and noticed that the AC cover had a very large hole in the top of it. It appears to have been there for some time. Additionally, when I checked the control board, there was a large wasps nest built directly on it. I purchased a replacement control board that is an exact match. The only difference is the red switch with the slide levers were actually toggles on the new unit...and did not have an 'on' label on it. Anyway, I replaced the control board and matched the new switch setting to what was on the original board (ironically, the only setting in the 'on' position on the original board was the furnace toggle). This, however, did not seem to solve my problem as the unit still does not work and the furnace comes on when power is applied to the house...it cannot be turned off. Now to my question: Do I have to replace my thermostat along with the control board? Could this be part of the problem as well? I have the 5 button Dometic thermostat. Any advice is appreciated.

Thanks in advance!

Roger

[chin_k]

This is a tough one there. I think you can manually control the AC without the thermostat by connecting the wires in specific way. From working with my house AC, I think there are two wires for the fan (one low speed, one hi speed), and one wire for AC and one wire for heat pump. You may want to see if there is a way to turn the fan by shorting the wire... I think the safest thing is to call the manufacturer and ask them if the current thermostat is compatible with the new control broad, and if there is a way for you to trouble shoot by connect the control wires to make sure the AC/control board is working properly, before replace the thermostat.

[caconcourse]

This sounds like it may be a wiring mixup. There are two phone-type (RJ11) cables in the AC/Furnace wiring that may be mixed up. One is the digital control cable between the 5-button thermostat and the AC. The other is a two-wire control cable for the furnace. It sounds like they may swapped in your wiring. I think the control cable is a little special in the RJ11's are installed in a "null modem" type configuration.

At any rate, I would inspect those RJ-11 connections and try unplugging one at a time or moving things around to see how things change.

[roscott]

Thanks for the responses. I'll check the RJ11 connections, but this was happening prior to replacing the control board, and to my knowledge, no previous work had been done. If that does not solve the issue, I'll call Dometic. Thanks for the advice.

[68camaro]

If you haven't seen this thread check it out: viewtopic.php?f=7&t=1532&start=10

I purchased a new replacement a/c from Dometic last spring, I could have used the existing thermostat with a control board mod but decided to replace with dated LED version.

Word of caution - Dometic retail tech help SUCKS.....A customer service rep told me I was rude because I kept asking her which version of the specs she was giving me was the accurate one! She kept contradicting herself and got very upset I would ask for clarification, forget asking for manager.....

[roscott]

Update: it turns out that it was a combination of things...most likely a short in the system caused by the wasp's nest. Anyway, Replacing the control board fixed the AC/Heat Pump issue...I just needed to do a reset of the thermostat and ensure the breaker was back 'on' (mobile RV repair guy came out to assist) The furnace blower staying on was an issue with its own controller board getting damaged (ie. most likely wasp related). I left the power disconnected from the furnace so the fan would not constantly blow. I really don't need it anyway as the heat pump will take care of any fairly cold weather instances I may be in. So, for about $400, I have a suitable outcome.

Thanks all, for the input and replies.

Roger

[chin_k]

Glad that you were able to troubleshoot the issue.

I used heat pump almost all the time, esp. when I hook up to shore power. This way, I am not paying for the propane. The heat pump should work for temperature as low as near freezing or even as low as 25F, but efficiency drops a lot. It is still better for the environment than burning propane, however.