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Need AC/Heat troubleshooting ideas

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Jim
 Jim
(@j_a_wolfe)
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Morning all. Need some ideas before I dig into why I don't have electric heat from the main unit.

First, it's been working fine, just the way it's supposed to up until today. Went to turn electric heat on and it didn't come on but defaulted to gas. I made sure we were only set at 2 degrees above ambient which is normally fine. Even at 1 degree above it went to gas. Checked AC side of thermostat and unit comes right on so I know there's power up there. It finally did go to electric but took a few tries.

Now - here's the one difference - we are in a spot with 30a only. Think it might be a voltage/amps issue and the unit is switching to gas because of that ? I know it's a smart thermostat but wasn't sure if it is test smart.

Ideas are appreciated. Thanks all !

 
Posted : May 6, 2018 11:11 AM
Jim
 Jim
(@j_a_wolfe)
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Hi Vaughn,
I was hoping I would see some response to your issue. I am having the same issue and, it just started after a year and a half working fine. I found that if I set the temp below ambient, slide to elec heat, then reset thermostat it works fine. That is just a work around though. Wondering if it may be the slide switch. Still searching.

 
Posted : May 17, 2018 7:29 PM
Jim
 Jim
(@j_a_wolfe)
Posts: 10846
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I would suggest that everyone look into getting a Hughes voltage compensation transformer , it also serves as a surge suppressor. Basically what happens is when a high draw device is trying to start up the voltage drops way off and if your on a 30 amp service the wire size to the pedestal is smaller and causing the voltage to be even lower with high draw AC unit. The Hughes unit as a Auto turn on to add 8% more voltage , its the voltage that starts your AC unit so if it drops below 110 volts on start up it make getting a hard start compressor almost impossible to start. this unit just plugs in . This is my 2nd RV using one of these , they work and there is zero drawbacks to having it plugged in. Campers world sells them and other venders like Teewtys rv.
https://hughesautoformers.com/product/50-amp-12000-watt-booster-and-surge/

 
Posted : May 18, 2018 7:14 AM
Jim
 Jim
(@j_a_wolfe)
Posts: 10846
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Need a little more information...

What was the actual temperature outside and inside at the time you tried to use the Heat Pump?

Which Heat Pump are you using? (Dometic, Coleman). We have the Coleman Mach 48004-969 on the 38K.

When you turned on the unit, how long was it before you had any kind of reaction? (Heat Pump or Furnace)

Does the A/C side work?

Do you have a Voltage Meter? What was the Voltage at the time? Do you have a generator? Did you try running the A/C on the Generator set?

The 30 Amp service will have nothing to with it. The Voltage could. Think of a water hose...A 30 amp service is a 1/2" water hose. A 50 amp service is a 3/4" hose. The voltage is the water pressure. Do you have a full 120 pounds of pressure? Or do you have 113 pounds of pressure? Do you have both legs? Or is it possible the RV is only getting 1 leg? In other words, is everything working in the RV where your are? is the Heat Pump your only issue?

Furnaces work strictly on 12VDC Battery (Fan and controls) (Shore power feeds 120VAC thru a rectifier/converter that keeps the batteries charged). The Heat Pump works on 120V.

What year model is your RV?

If you have already solved the problem, please let us know.

 
Posted : May 18, 2018 7:32 AM
Jim
 Jim
(@j_a_wolfe)
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Hi Vaughn;
Just got off the phone with Coleman-Mach. I have not tried the procedure yet but you will understand why as I proceed.

The thermostat has a protocol it follows. Using a temp differential to decide if the heat pump is within it's op range. If not, it defaults to furnace. It also has a three strike rule. Three defaults and the thermostat locks out the elec heat function for two hours and then the system has to be cleared. Here is the procedure:

- Wait 2 hours from the last attempt to start the HP. During this time the furnace can be running. (Edit: Make sure the thermostat is set to Gas Heat during this period and not running furnace on a default withe switch in the Elec Heat position)
- Turn the unit off
- Set the call temp 10* below room temp
- Slide the switch to electric heat
- Raise the call temp to 2* above room temp. After a few seconds the HP should start
- Lower the call temp below room temp to satisfy the thermostat. The HP should shut off.This satisfaction clears the three strikes
- Now raise the call temp NO MORE THAN 5* above the room temp.
- As the room temp rises, raise the call temp in no more than 5* steps to the desired temp
I have an hour before I am going to try. Then we'll see.

Hope this helps, and....works.

Bob

YeeHaw! It works!!

 
Posted : May 18, 2018 4:29 PM
Jim
 Jim
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Bada Bing Bada Boom. It worked!

 
Posted : May 18, 2018 7:13 PM
Jim
 Jim
(@j_a_wolfe)
Posts: 10846
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Ain't electronic stuff great ??

 
Posted : May 18, 2018 10:44 PM
Jim
 Jim
(@j_a_wolfe)
Posts: 10846
Member
Topic starter
 

Yeh......when it works..........

 
Posted : May 19, 2018 10:19 AM
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