EV Mode with Defrost On

Old 01-12-2016, 04:45 PM
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Join Date: Jan 2016
Posts: 3
Default EV Mode with Defrost On

Hi all. I have an 06 MMH with about 110,000 miles on it. I purchased it in 2010 as the 2nd owner. Had just under 50k at that time.

Over the past year or so I have been experiencing some issues with the car and it has been in and out of the dealer for a variety of issues. Most recently my thermostat was replaced. I'm in Northern Indiana with temps around 15 degrees today. As I was driving home today, I realized it had gone into ev mode while I had my defrost/floor heat setting engaged. This has never happened before (that I have noticed) and I was always under the assumption that the "red" settings for the fan (Max A/C, Defrost and defrost/floor) prevented the vehicle from going into ev mode. It continued to do this the entire ride home (maybe 8 miles) with two short stops where the car was completely turned off.

So of course this freaked me out as I have become increasingly more fearful that I am on the verge of some very costly repairs to keep the car going. I checked my manual and it says in these modes the engine will "typically run continuously" with these settings engaged. In searching around through online forums to see if others have experienced this I see over and over people advising others to make sure these settings are not engaged as it will keep the ICE on. And several definitive statements about the vehicle "will never engage ev mode with these settings on."

I have yet to find a post about anyone experiencing ev mode while these settings are on so I caved and make a green hybrid account to ask for help. I have used this forum for many years when I had mechanical concerns as well as to learn to drive my MMH more efficiently. And frankly, gotta say I don't mind it going into ev mode more as long as that doesn't mean something else is broken.... Which I have to assume there is since this has never happened in the 6 years I've had the car.

So, if you can help, please do so in lay terms. I don't know how to do internal temp readings, scan for codes on own, etc. If it's acting up I usually have the codes read at Auto Zone and then do my research so I am relatively prepared when I take it to the dealer... and often to give them some direction on what might be the problem because they frankly still don't seem all that versed in Hybrids even though I have to see some kind of special tech.

My apologies if this has been posted elsewhere. I've been looking around online for about an hour and haven't found anything about ev mode with defrost on.... just lots about turn defrost off to go into ev mode. Any thoughts would be appreciated. And thanks for being such a great resource to me the past few years.
Old 01-12-2016, 06:24 PM
gpsman1's Avatar
Hybrid and Ethanol Expert
Join Date: Mar 2005
Location: All over the Central U.S.
Posts: 3,589
Default Re: EV Mode with Defrost On

It is because you live in Indiana. No really! Actually it is because you are in the cold.

If you are below 32 degrees the A/C system which runs from the engine for both cooling and de-fogging via dehumidifying the air, cannot run.

If the A/C cannot run, which is the only reason to block out EV mode in the "red" settings on the climate control, then EV MODE is allowed.

This happens in my 2005. I am amazed software programmers thought of this but it's true.

I think your car is normal. Mine does this below 32 degrees. (sometimes 33-34 degrees). A few others HAVE posted similar results and confirm this.

😀 John
Old 01-12-2016, 06:36 PM
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Join Date: Jan 2016
Posts: 3
Default Re: EV Mode with Defrost On

Thank you so much for the reply. Makes me feel much better!
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