Penquin Air/Heat Pump Reversing Valve

[Phil and/or Sue]

I have a problem with my air conditioning and heat pump functions from my Dometic Penguin HVAC unit.

I had thought that the reversing valve normally allowed cooling, and was energized to reverse refrigerant flow to the coils thereby providing the heat pump function. This appears not to be the case.

When I replaced the thermostat with a Comfort Control Center, I also had to replace the control board (with p/n 3312227.000) in the rooftop A/C unit.

After install, I was getting hot air from my cooling cycle, and cold air from my heat pump function. I thought my re-wiring was suspect, so a Dometic email got a response with schematics, and I found no issues.

The diagnostic mode (press Program, Fan and F/C button while off) allows step by step function cycling. When I turn the Reversing Valve on, I get a nominal 120v sent to the reversing valve (verified by meter).

When I disconnect the reversing valve wire harness, I get hot air in all modes, which tells me that the reversing valve is normally in heat pump mode, and requires power to get to (what I thought would be normal) cooling mode. Seems odd to me, but maybe the old control board took care of that.

Maybe the dipswitches need to be different than what I did (only Heat Pump and Furnace switches are on).

I have sent a message to OutofDoorsMart (where I bought the parts), but maybe someone else has experience with this.

Any thoughts would be appreciated.

Phil

[HiJoeSilver]

What wire did you run from the unit to the CCC. Wasn't by chance regular phone line? I think you would have had to run something since the SZLCD and CCC use different wires. If you used regular phone line, that's probably the problem. In their infinite quest for a buck dometic uses a phone line with phone jacks on the ends, but to keep people from simply being able to go buy phone line in store they require one end to be reverse wired. If it's not that may be what's causing the unit to essentially run backwards.
Hope that makes sense and helps.

[Phil and/or Sue]

The wire from the CCC to the rooftop is good (6 wire, correctly oriented).

As I boil this down, it seems to be a question of how the reversing valve is supposed to work. When completely isolated electrically, it appears to be reversed. That is, when I pulled the electrical plug off the terminals so it was unpowered, I got heat in the Heat Pump mode, as well as heat when I tried the Cooling mode.

I was wondering if the old tstat/control board kept the reversing valve off for Heat Pump, and powered it for Cooling. I still have them (packed somewhere in our move), but I'm hoping to find out about what I have installed, and whether I need to change settings on the board. Maybe it's the wrong board for a/c...

[Phil and/or Sue]

By the way, thanks for your thought and time.

Phil

[nrgtrakr]

But it worked normal before replacing the thermostat ...?

[lewster]

Dometic's reversing valves are always on heat pump mode in resting state unless energized by the t/stat when it calls for call for cooling, so your last diagnosis is correct! Heat in resting state, cooling in energized state.

The next thing you have to look at is the compatibility of the board to the CCC-II and your specific upper unit. Call Dometic and give them the part numbers to be certain that you have the correct board.

Also, depending on which board you have, you might have to set the DIP switch for 'heat pump' if it's present in the DIP switch line. If you ran your furnace lines (should be 2 blue wires) into the board, you will also need to activate the 'furnace' DIP switch.

As I recall, the communication cable is a 4 wire phone cable with one R-11 reversed from the other. You might try 2 things: use a 4 conductor cable and try placing it into the second RJ-11 union at the base of the upper unit.

Keep us posted on your progress.

[Phil and/or Sue]

Thanks for your message. My reply got lost this morning.

I am going to talk to Out Of Doors Mart to see how they determined the control board they sold me. I presume I gave them my rooftop info, but I'll find out. Maybe there's a dipswitch setting I can manipulate (although it doesn't look like it).

Phil

[Phil and/or Sue]

Out of Doors Mart has been talking with Dometic. No answer yet, but hopeful that either already - installed board can be configured to support my A/C, or some other simple fix can be found.