Thermostats on cool with no 120VAC to ACs... any harm?

[Second Chance]

This is a travel day question. Is there any harm in leaving the thermostats on and calling for AC when not connected to shore power (no 120VAC to AC units)? These are Coleman Mach 15s with individual thermostats. I'm wondering if there's any risk of damaging a relay or something if there's a constant call for cooling but no AC to power the ACs (clear as mud?).

Rob

[Yoda]

Rob - I don.t think so for traveling unless there is a constant 12V draw. However when you connect to shore power the next time it might create a pretty good surge trying to start as you plug in. That could cause issues.

Just thinking
Keith

[JCR GD]

I guess it would depend on the duty cycle of any relays involved. Since the 12v load is low, I would think it wouldn't hurt.

[StephenO]

I would ensure that the breaker at the pedestal is off when connecting to shore power at your destination if the AC is switched on. Like Yoda said, you'll probably have a pretty good inrush current and you would want to ensure you have a solid connection for it, and not having the plug halfway connected.

I doubt the OEM thermostat would care, but just incase you've upgraded yours, our home thermostat will throw an error if the call for heating or cooling is taking too long and no change in temperature is observed. Again, our home has a smart thermostat though and the OEM one would be fairly simple.

[Second Chance]

I would ensure that the breaker at the pedestal is off when connecting to shore power at your destination if the AC is switched on. Like Yoda said, you'll probably have a pretty good inrush current and you would want to ensure you have a solid connection for it, and not having the plug halfway connected.

I doubt the OEM thermostat would care, but just incase you've upgraded yours, our home thermostat will throw an error if the call for heating or cooling is taking too long and no change in temperature is observed. Again, our home has a smart thermostat though and the OEM one would be fairly simple.

Thanks... I always make sure the 50 amp breaker is off before plugging in. I usually just leave one AC on to prevent both coming on at the same time initially. It helps get a head-start on cooling the rig down while I finish unhitching and leveling on days like today. The thermostats are OEM and have never thrown an error.

Rob

[StephenO]

It helps get a head-start on cooling the rig down while I finish unhitching and leveling on days like today.

Rob

Lately on days like today, I am jealous of everyone with power sites. We are headed to a campground with no power this weekend and there are heat warnings again

[Jlawles2]

Second Chance Rob, the AC's should be on opposing legs of the 50A service so starting both at the same time should not be an issue. I've done it by accident before, but since there are 2 or 3 of us moving around the unit, it gets unhitched and leveled before any of the utilities are hooked up. After the jacks finish their dance and the power is hooked up, she heads in to start A/C and get slides out while I finish water and sewer.

[pengle]

Second Chance Most of us have surge protectors that won't pass the voltage to the load of the ACs (if they are on) until 15 seconds (Progressive Dynamics) or so after you plug into the pedestal. So, even if you forget to check and the circuit breaker is on, you won't create an arc between the male plug end and the receptacle with a surge protector installed.

[Second Chance]

Second Chance Most of us have surge protectors that won't pass the voltage to the load of the ACs (if they are on) until 15 seconds (Progressive Dynamics) or so after you plug into the pedestal. So, even if you forget to check and the circuit breaker is on, you won't create an arc between the male plug end and the receptacle with a surge protector installed.

Yes - we have a Progressive Industries HW50C, so thanks for that thought.

Rob

[bertschb]

Rob- I still can't believe you actually asked a question here. That's almost like Cate&Rob asking a question about plumbing.

[Second Chance]

Rob- I still can't believe you actually asked a question here. That's almost like Cate&Rob asking a question about plumbing.

Brian, I'll take that as a compliment (I think). The fact is, I don't have expertise in RV air conditioners or their control circuits. I thought there might be folks around who do. To quote an infamous former Secretary of Defense, "There are known knowns, there are unknown knowns, there are known unknowns, and there are unknown unknowns..."

Rob

[Jlawles2]

Second Chance Rob, You might try and see how the unit reacts when you first turn it on. I think the fan comes on for several seconds, then the compressor kicks in. If that's the case, then it should not make that much of a difference. The only time you may have issues is when connected to a 30A instead of 50A.

[Second Chance]

Second Chance Rob, You might try and see how the unit reacts when you first turn it on. I think the fan comes on for several seconds, then the compressor kicks in. If that's the case, then it should not make that much of a difference. The only time you may have issues is when connected to a 30A instead of 50A.

Yeah - I'm pretty sure that's the case. My primary concern, though (my original question), was whether or not a constant call for cooling from the thermostat when 120VAC was not present for the AC unit during travel would harm anything (like relays) on the AC control board.

Rob

[Jlawles2]

No different than it running all day to combat the sun.