Electrical problems w/Mach 10 Coleman

SeeTheUSA · 02-28-2022, 05:20 PM

Our 2018 View has a Coleman Mach Ten 15,000btu with heat pump and it began acting strangely. First manifested itself when I was exercising our generator at the storage facility. What I typically do each month is start the generator, let it power up and run for a few minutes, then load it by running the Mach Ten heat pump or air conditioning, depending on ambient temperatures.

When I toggled the thermostat for electric heat the other day, the Mach Ten fan started as usual, but when the heat pump portion tried to kick in, the generator began to strain, lost rpm then within about 5 seconds stalled (perhaps it shuts down that way by design when it detects an issue). The generator control panel (it’s an Onan RV QD 3200) then displayed “SHORT CIRCUIT!”

Since then I’ve inspected all I know to eyeball regarding the generator, electrical panel, wiring and transfer switch. I discovered nothing tripped, nothing burnt, no loose connections.

I’ve attempted to operate both the A/C and Electric Heat with the generator and shore power. The Electric Heat doesn’t heat but the A/C seems to be working with either power supply. After quite a few cycles of trying things, I’ve never tripped a 20 amp breaker at home shore power, but did once stop the generator when turning on the A/C and got the “SHORT CIRCUIT!” alert. The next time I tried it, it worked fine. Otherwise have successfully operated the A/C on both generator and shore power. Simply get no heat from the Electric Heat, though.

Any thoughts? Is my Mach Ten about to go south without me?

Appreciate your help.

powercat_ras · 02-28-2022, 06:46 PM

There is a 120 volt operated reversing valve in the heat pump that may not be working correctly , that is the only thing that is different electrically and mechanicaly between AC mode and Heat Pump mode. Your unit does not have any test ports for a AC tech to connect gauges to determine the problem. Someone might be able to take it down from the roof and add test/charge ports in a specialty AC workshop. If it was determined the reversing valve had failed this could be replaced in a speciality AC workshop. That said rooftop RV Heat Pumps are not designed to be serviced in this way, so it will be out of most AC workshop's comfort zone to work on.

All that said, you would be hundreds of dollars in just to pay someone to figure out what is wrong and the eventual cost to fix could end up close to replacement cost.

If it works fine in AC mode, here's what's different when it is in heat pump mode ...

The reversing valve "flips" the inlet and outlet sides of the compressor around ...

The 120 volt operated reversing valve changes refrigerant flow direction in heat mode, so that the hot compressed gas that leaves the compressor goes to the inside heat exchanger, then goes thru the expansion valve that causes it to liquify and become cold where the refrigerant moves between the inside and outside parts of the AC. Then the outside heat exchanger causes the liquid to vaporize and give up the cold to the outside air. The compressor compressing the gas causes it to heat up in a continuous cycle so long as the compressor and dual exchanger blowers fan motor is running.

SeeTheUSA · 03-01-2022, 07:24 AM

Thanks Randy. Maybe a dreaded trip to the shop of my choice is next.

Vinnfizz · 03-06-2022, 05:34 PM

Our Coleman-Mach 10 A/C heat pump quit on us in our new 2021 Winnebago 34T. The compressor would kick in but drew very low amperage when it started. Tech said he suspected the Freon leaked out and compressor was running but not pumping anything. Eventually it would have locked up from lack of the oils circulating. Thankfully it was replaced under warrantee as fall temperatures allowed just using only the front regular A/C but living without the rear in coming spring weather in Florida would be difficult for one A/C to keep up. Plus waiting for our dealer to get around to getting it fixed took three months in the Covid supply channels. Wish you luck!

bkg · 03-06-2022, 08:07 PM

Quote:

Originally Posted by SeeTheUSA

Our 2018 View has a Coleman Mach Ten 15,000btu with heat pump and it began acting strangely. First manifested itself when I was exercising our generator at the storage facility. What I typically do each month is start the generator, let it power up and run for a few minutes, then load it by running the Mach Ten heat pump or air conditioning, depending on ambient temperatures.

When I toggled the thermostat for electric heat the other day, the Mach Ten fan started as usual, but when the heat pump portion tried to kick in, the generator began to strain, lost rpm then within about 5 seconds stalled (perhaps it shuts down that way by design when it detects an issue). The generator control panel (it’s an Onan RV QD 3200) then displayed “SHORT CIRCUIT!”

Since then I’ve inspected all I know to eyeball regarding the generator, electrical panel, wiring and transfer switch. I discovered nothing tripped, nothing burnt, no loose connections.

I’ve attempted to operate both the A/C and Electric Heat with the generator and shore power. The Electric Heat doesn’t heat but the A/C seems to be working with either power supply. After quite a few cycles of trying things, I’ve never tripped a 20 amp breaker at home shore power, but did once stop the generator when turning on the A/C and got the “SHORT CIRCUIT!” alert. The next time I tried it, it worked fine. Otherwise have successfully operated the A/C on both generator and shore power. Simply get no heat from the Electric Heat, though.

Any thoughts? Is my Mach Ten about to go south without me?

Appreciate your help.

Warren, reading your post carefully, I'm trying to sort what are you calling "electric heat". You mention heatpump which is reversed operation of the cooling circuit, however, you also mention electric heat - this is an option for a true electric heat strip which can be added to the Coleman (or comes equipped if ordered). If you do have the electric heat option, I would unplug it at the control box and try everything all over again with the heat strip unplugged. If it works like it should, there is a faulty component in the electric heat unit which can be anything from a heat element insulator to a diode. The easier route might be to replace the entire strip (note: the part in the link was not matched to your particular Coleman unit - the link is simply for reference).
If you have knowledge on the use of an amp meter, I would use it to check the amp draw of the Coleman in different cycles (cool/heatpump/heatpump with heat strip) and try on each shore power and generator power.

Bobby

Geosman · 03-07-2022, 07:50 AM

I would gamble that the electric elements are not meant to be run via the generator and that if they are trying to run in combination with the compressor in heat mode the load is well above what a 3200 W generator will supply for the starting load causing the generator to fault. The starting current on the Mach 10 is roughly 4 times the running current. It occurs for a split second but with additional loads at the same time it is enough to stall out the generator. I installed an RV soft start kit on my Mach 10 and have no problems but also do not have electric elements with the heat pump. My thermostat controls the propane heater at a significantly lower load if not using the heat pump function.

SeeTheUSA · 03-07-2022, 08:08 AM

Thanks for the responses …

I do not have an electric heat strip add on, what I was referring to as “electric heat” is the reversed operation of the compressor. Sorry for the confusion.

I’m still sorting out the problem, but not quickly.

**creativepart** · 03-07-2022, 08:20 AM

Reading the original post it seems clear he is talking about simply running the A/C unit on the heat pump function is not working on generator power.

And, his RV is designed to run the Mach 10 unit on generator power.

It does sound like his Mach 10 is having a problem that is using excessive amperage when starting in heat pump mode that he needs checked out. That is unless he is also running another large amperage device at the same time, such as the microwave, a coffee maker, toaster oven, space heater or similar.

Running the Mach 10 with any of the above high amperage items on generator can overload the generator and cause it to bog down

Geosman · 03-07-2022, 08:28 AM

If you were attempting to start the compressor in the heat mode after setting in the cold for a long time, it may have been flooded with refrigerant which will migrate to the coldest portion of the heat pump system. The compressor is meant to manage vapor and not liquid. The fact that you were able to later start it in AC and apparently again in heat? tends to verify that warmth added by the windings when it faulted the generator was sufficient to boil off residual refrigerant that had migrated to the compressor. There is a thermal / high current sensor attached at the compressor terminals that will often prevent it from tripping a breaker but still the current load is too great to manage with a 3200 watt generator and sometimes even a 20 amp land line. If possible I would suggest using a 30 amp 120 volt land line or just know that if using a 20 amp line and 12 gauge extension cord to run the heat pump that the chord and circuit are running close to their limit and will likely over-heat the plug connections or trip that 20 amp breaker if left on for a sustained period.
If you need to run the Mach 10 via generator, I strongly suggest you might invest in the RV soft start.
https://www.softstartrv.com It will likely overcome your startup issues.

Geosman · 03-07-2022, 09:04 AM

Reading back through your original post, I now get the impression that despite the ability to run in the AC mode that it simply faults the generator whenever set for heat?
Powercat's response may be closer to the issue when he suspected the coil or wiring to the reversing valve by be causing the short circuit. If you are not into HVAC service it is best to have a tech check the reversing valve coil to see if it is burned out or shorted causing your issue. Replacements should be easy but require knowledge of the coil manufacturer and its voltage to obtain a correct replacement.

bkg · 03-07-2022, 05:44 PM

Quote:

Originally Posted by SeeTheUSA

Thanks for the responses …

I do not have an electric heat strip add on, what I was referring to as “electric heat” is the reversed operation of the compressor. Sorry for the confusion.

I’m still sorting out the problem, but not quickly.

Then I suggest what I stated above: "If you have knowledge on the use of an amp meter, I would use it to check the amp draw of the Coleman in different cycles (cool/heatpump)". If operating a amp meter is a weak area for you, then do you have an EMS such as the Progressive Industries HWS30 or similar. Most of these have a display that will provide amp draw.
You need to see what your amp draw is before running the A/C on both shore power and generator then check again with just fan on, then the amp load on cooling. This information will help determine if there is something wrong with the Coleman, If anything, it could likely be a failing/failed capacitor. Voltage surges tend to stress an aged capacitor.

Bobby

SeeTheUSA · 03-17-2022, 10:34 AM

I had my dealer troubleshoot the problem, conclusion was the heat pump mode isn’t functioning properly. New unit has been ordered, ETA four to five months.

Thanks all for your replies.

Geosman · 03-18-2022, 09:56 AM

Just wish you were here in northern KY I would check it myself. With over 40 years of heat pump control knowledge, I suspect there could be a simple low-cost solution.

SeeTheUSA · 03-18-2022, 09:38 PM

Quote:

Originally Posted by Geosman

Just wish you were here in northern KY I would check it myself. With over 40 years of heat pump control knowledge, I suspect there could be a simple low-cost solution.

Wish I was close! Sure seems to be a fairly simple malfunction. Like so many things nowadays, there are more parts changers than technicians.

Thanks.