How to Tell If RV Thermostat is Bad?

The RV thermostat is part of the system that helps to regulate the temperature in the motorhome, trailer, or camper.

Sometimes, you may be getting strange readings, an unresponsive display, or a furnace that activates and deactivates under odd circumstances.

How to Tell If RV Thermostat is Bad?

A thermostat may not instantly fail and no longer respond. It’s a little like when a battery that’s down to a 5-10% charge.

Should that happen, the control unit it’s powering could work intermittently or erratically sowing confusion. Is there a ghost in the machine? Hopefully not!

Do bear in mind that some of the causes of bad thermostats can overlap with other ones.

So, while the list below of how to tell if the RV thermostat is bad is not exhaustive, it’s also a good idea to consider other likely causes.

Do some RV thermostat troubleshooting (we have a troubleshooting section to take you through step-by-step what to do).  

How do I know if I need to replace my thermostat? Look at these possible indicators first:

  • Furnace or AC won’t activate – When the thermostat is either not providing a reading or it’s an inaccurate one, then depending on the settings on the control panel, it may prevent the furnace or AC from activating. This is because the system relies on the thermostat’s reading about whether it’s already too hot or too chilly. Of course, that may not be true, but that’s what a dying RV thermostat is communicating incorrectly.
  • Short-cycling problems – The RV or camper’s HVAC system may fail to complete a full cycle. Therefore, if the furnace should be warming the living space up or the AC cooling it down, the system deactivates before the ideal temperature is achieved. Either you can try again, and the thermostat gives the correct readings on the second occasion and the living space becomes more comfortable, or the same thing repeats itself.
  • A failure to communicate – Changing a temperature setting on the control panel typically creates clicking sounds when the action triggers the cooling or heating to start up. Then once that happens, the clicking sound usually goes away. However, when the clicking doesn’t occur or it does, but nothing happens, then there’s a failure to communicate. It’s like at this point that the RV thermostat requires replacing pronto. It’s not going to get any better from there!
  • Programmed memory issues – When the thermostat has previously accepted some programmed settings but now it’s completely lost the plot, then you want to despair. Reprogramming the thermostat is the first thing to try. However, if the new settings disappear again or don’t work correctly, it’s probably either a battery issue or something more serious.

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Coleman 83303862 Digital Thermostat

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What Causes a Thermostat to Go Bad in Your RV?

While a decent RV thermostat probably has a useful life of 10 years and possibly even longer, it’s still a piece of electronics.

We all know that electronic devices – and parts within them – can fail unexpectedly.

While the thermostat itself might have a decade or longer of potential life, that doesn’t rule out RV AC thermostat troubleshooting or work needed to the RV furnace thermostat to resolve small problems.

Deteriorated wiring, dust infiltration, a bad circuit board, a display with a life of its own, or a set of faulty batteries could be causing new issues.

Also, the casing could have become partially dislodged, was knocked or damaged resulting in it no longer sitting flush, the digital display on the front could have failed, or it might be something else entirely.  

Read Also: How to Repair Delamination on RV

RV Thermostat Troubleshooting

A bit of troubleshooting is necessary to assess RV thermostat problems.

This way, a proper determination can be made.

Think of it like a doctor running tests to double-check their previous diagnosis; it avoids you replacing anything before it’s needed.  

How to Test RV Thermostat?

Whether you’re having Dometic RV thermostat problems or some Coleman Mach Thermostat troubleshooting is required, follow the suggestions below:

  1. Battery failure? Newer digital thermostats need one or more batteries to provide power to the control unit. It’s a good idea to swap out the batteries regardless of how new they are and to re-check all the malfunctioning features. Low-charge batteries can deliver confusing results, but a fully drained battery makes the thermostat look dead too.
  2. Examine the digital display. It should be lit up. If the light is dim, and it’s a backlit or a side-lit display, then perhaps the internal bulbs have failed or are failing (many laptops with an older TN panel have this problem). If there’s no screen display at all, then it could indicate the thermostat is not sending information through to show on the screen. It might also suggest that the screen display itself has failed.
  3. Are the circuit breakers fooling you? It would be easy for the circuit that controls the heating and cooling equipment to have silently tripped. Usually, you won’t know unless you double-check it to be sure. If one or more have tripped, then reset the affected ones, and check the thermostat and related facilities once again.
  4. Consider where the thermostat is positioned. An RV thermostat could be situated in a place where direct sunlight is shining on the thermostat panel, which didn’t happen previously. Alternatively, any holes or gaps behind where the thermostat is installed could allow cooler air to affect readings. Either of these two situations could change the thermostat’s internal temperature readings leading to inaccurate results.
  5. Settings go wonky! When other factors like failing batteries are a problem, then the settings can get messed up too. Decisions relating to the temperatures for when the heating should come on/off or the AC, respectively, can mysteriously change due to other factors. So, don’t get thrown off by that. Account for other possibilities that could be playing with your settings as if there’s a ghost in the machine.   

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Is it a Digital RV Thermostat Heat Only Model?

If the RV or camper is new, or it’s previously owned and the thermostat was replaced from the factory fitted model, you may believe you have a heat and cooling thermostat. However, you could be mistaken.

It’s an obvious yet easy mistake to make.

Perhaps your motorhome has an RV thermostat heat-only version, but you’re confused why you cannot get any cooling function to work (or you cannot find the option).

Not every system includes cooling.

You could add an AC unit and replace the RV thermostat with a digital heating and cooling model to manage the upgrade.

How Do I Reset My RV Thermostat?

The process to reset the RV thermostat if you believe it’s become “confused,” but the display panel is still functional, is to reset it.

Resetting might be either a soft reset or a hard reset; the latter will likely clear any programmed settings such as the times to turn on/off heating or cooling, whereas a soft reset usually doesn’t lose this information.

With RV digital thermostats, the correct procedure varies both between manufacturers and even between models in their range.

The most frequent way to perform a reset is to use a dedicated reset button.

This will then be held down for a fixed amount of time, typically around 4-6 seconds, to trigger the reset process (the duration may differ between thermostat models).

Sometimes, holding the reset button down for a longer duration will trigger a hard reset instead.

A power reset is a secondary process to try if the reset button isn’t doing anything, you cannot find it or the model doesn’t have one.

For battery-powered thermostats, removing the batteries for a short time and then putting them back in can trigger a reset.

Removing any internal fuse will also do it.

The wire harness could also be disconnected, and this might work too (turn off the power completely first for safety).

Failing all else, reaching the breaker panel and flipping the correct breaker to deactivate the RV thermostat for several minutes can work too.

Also, bear in mind that whether you own a Dometic DuoTherm 4, a Dometic 3 button, or a Coleman model, they each have a product manual that will include detailed instructions on how to reset their thermostat.

The manual will be available online for download.

When the general suggestions above do not seem applicable to your RV thermostat model, access the product manual for the next steps.

How Does an RV Thermostat Work?

The RV thermostat is what allows you to turn different features of your HVAC system on or off as required.

Wires come into the thermostat unit from the various systems, such as the furnace, AC, and so on.

Thermostats have different levels of sophistication for their control systems.

Also, many of the programmed settings are stored inside the circuit board. Should this begin to fail, it will need replacing.

The front panel commonly incorporates an LCD digital display or basic control system.

Depending on whether there are physical touch buttons or it’s a touchscreen panel (less common), this provides an interface to control the HVAC systems.

As such, the RV thermostat doesn’t just read the ambient temperature level in the living quarters but provides control over the systems with it too.

Closing Thoughts

With RV thermostats, care must be taken to avoid drawing erroneous conclusions.

A thermostat that’s currently playing up could be something as simple as a dud battery, dust on the wires causing connections to be touch and go, or the circuit board might be failing.

Methodical troubleshooting of the RV thermostat is required to rule out possible causes to reach the correct conclusion. Then you’ll know what needs replacing to fix the problem.

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