I'm sure this has been debated here before, but I haven't seen anything about it. If you shut off your A/C before shutting your engine down yield longer life to the A/C unit. Would it vastly effect voltage upon start-up? Or does this method only reduce the life of the on/off switch in the console by changing it just two more times each day? In the 2012 Ford Transit owners manual, it explained that you should shut down all devices first, including DC external devices and the radio, so I abide those instructions. In my Fiat book, it didn't mention anything. But I still did it. What are your thoughts?
A/C off when shutting off engine
- Thread starter 79sunrunner
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If you've noticed the radio and ac cuts off when starting so you're not really overloading anything.
I've noticed that too. hmmm
I shut off the A/C and switch to outside air about a block before I get to the house, but not to extend the life of the A/C or to reduce energy consumption. It's just to run hot dry summer air over the evaporator core for a little.
I'm in and out of cars all day and it seems to me that the ones that leave the A/C on all the time have a more mildewy smell on start up.
I'm probably not actually doing much to help, but it doesn't seem like I am hurting anything either.
I'm in and out of cars all day and it seems to me that the ones that leave the A/C on all the time have a more mildewy smell on start up.
I'm probably not actually doing much to help, but it doesn't seem like I am hurting anything either.
JHZR2
Staff member
My father always abided by the all off when shutting down, then verifying all off for startup. I guess his theory was less load from the old days.
Someplace I read to turn on the headlights before startup to "warm" the battery.
A vehicle like a transit can likely be fit with all kinds of high load devices, as its a working vehicle. That and/or legacy language put that there.
In good weather on a healthy system, likely nothing to ever worry about. But turning off some load likely is smart.
Now the AC system cycles regularly, so cutting power, which ends the cycle by declutching the compressor is nothing new. It will drop load on the engine at shutdown. But most AC systems won't allow the clutch to be engaged at startup anyway, so you're really just talking fan load, which can be 10A+!
Someplace I read to turn on the headlights before startup to "warm" the battery.
A vehicle like a transit can likely be fit with all kinds of high load devices, as its a working vehicle. That and/or legacy language put that there.
In good weather on a healthy system, likely nothing to ever worry about. But turning off some load likely is smart.
Now the AC system cycles regularly, so cutting power, which ends the cycle by declutching the compressor is nothing new. It will drop load on the engine at shutdown. But most AC systems won't allow the clutch to be engaged at startup anyway, so you're really just talking fan load, which can be 10A+!
JHZR2
Staff member
Originally Posted By: Spazdog
I shut off the A/C and switch to outside air about a block before I get to the house, but not to extend the life of the A/C or to reduce energy consumption. It's just to run hot dry summer air over the evaporator core for a little.
I'm in and out of cars all day and it seems to me that the ones that leave the A/C on all the time have a more mildewy smell on start up.
I'm probably not actually doing much to help, but it doesn't seem like I am hurting anything either.
Not sure what Arlington youre in, but I'm guessing TX or something. Doing this in humid areas just makes for humid air in the cabin.
I shut off the A/C and switch to outside air about a block before I get to the house, but not to extend the life of the A/C or to reduce energy consumption. It's just to run hot dry summer air over the evaporator core for a little.
I'm in and out of cars all day and it seems to me that the ones that leave the A/C on all the time have a more mildewy smell on start up.
I'm probably not actually doing much to help, but it doesn't seem like I am hurting anything either.
Not sure what Arlington youre in, but I'm guessing TX or something. Doing this in humid areas just makes for humid air in the cabin.
On older cars I know that the compressor would still be engaged if you left the AC on; likely on newer computer controlled vehicles they are disengaged on startup.
I like Spazdog's idea of running non conditioned air through the system on shut down; makes sense to warm it up some to reduce condensation.
I like Spazdog's idea of running non conditioned air through the system on shut down; makes sense to warm it up some to reduce condensation.
from spazdog "It's just to run hot dry summer air over the evaporator core for a little." Thats the same reason I shut mine off 5 miles before I reach point B while driving.
I shut everything off. Habit I got into 62 years ago when I first got my license. Besides my Dad said to do that.
Originally Posted By: CharlieW618
I shut everything off. Habit I got into 62 years ago when I first got my license. Besides my Dad said to do that.
I do the same out of habit, just hasn't been 62 years.
Dad always said back then, turn everything off then shut off the engine. If you have a battery on its last leg, the little voltage boost from less load just might make a little difference next start.
I didn't do it because i believed him or not at the time, I did it because it was his vehicle and what he wanted. Better than getting a mouthful from him anyway. So it became habit.
I shut everything off. Habit I got into 62 years ago when I first got my license. Besides my Dad said to do that.
I do the same out of habit, just hasn't been 62 years.
Dad always said back then, turn everything off then shut off the engine. If you have a battery on its last leg, the little voltage boost from less load just might make a little difference next start.
I didn't do it because i believed him or not at the time, I did it because it was his vehicle and what he wanted. Better than getting a mouthful from him anyway. So it became habit.
Originally Posted By: CharlieW618
I shut everything off. Habit I got into 62 years ago when I first got my license. Besides my Dad said to do that.
I shut everything off when I turn the key off. When I restart, everything is automatically cut off while the starter is engaged. This has been my habit since I got my license in 1952. However, I did not get an airconditioned car until the middle 1960's. I'll be 77 this year. Did you have an airconditioned car 62 years ago?
I shut everything off. Habit I got into 62 years ago when I first got my license. Besides my Dad said to do that.
I shut everything off when I turn the key off. When I restart, everything is automatically cut off while the starter is engaged. This has been my habit since I got my license in 1952. However, I did not get an airconditioned car until the middle 1960's. I'll be 77 this year. Did you have an airconditioned car 62 years ago?
Originally Posted By: Spazdog
I shut off the A/C and switch to outside air about a block before I get to the house, but not to extend the life of the A/C or to reduce energy consumption. It's just to run hot dry summer air over the evaporator core for a little.
I'm in and out of cars all day and it seems to me that the ones that leave the A/C on all the time have a more mildewy smell on start up.
I'm probably not actually doing much to help, but it doesn't seem like I am hurting anything either.
I do the same. And maybe for more than a block. Dry it out a little and I think it helps keep down that stank.
I shut off the A/C and switch to outside air about a block before I get to the house, but not to extend the life of the A/C or to reduce energy consumption. It's just to run hot dry summer air over the evaporator core for a little.
I'm in and out of cars all day and it seems to me that the ones that leave the A/C on all the time have a more mildewy smell on start up.
I'm probably not actually doing much to help, but it doesn't seem like I am hurting anything either.
I do the same. And maybe for more than a block. Dry it out a little and I think it helps keep down that stank.
Originally Posted By: 79sunrunner
from spazdog "It's just to run hot dry summer air over the evaporator core for a little." Thats the same reason I shut mine off 5 miles before I reach point B while driving.
lol, I'd run my A/C about once a month if I did that.
There is no reason to do this. Even on older vehicles the compressor should be on a circuit not hot in 'start' so it wont actually be pulled in during cranking. On modern vehicles its computer controlled so even less point.
from spazdog "It's just to run hot dry summer air over the evaporator core for a little." Thats the same reason I shut mine off 5 miles before I reach point B while driving.
lol, I'd run my A/C about once a month if I did that.
There is no reason to do this. Even on older vehicles the compressor should be on a circuit not hot in 'start' so it wont actually be pulled in during cranking. On modern vehicles its computer controlled so even less point.
Originally Posted By: Colt45ws
Originally Posted By: 79sunrunner
from spazdog "It's just to run hot dry summer air over the evaporator core for a little." Thats the same reason I shut mine off 5 miles before I reach point B while driving.
lol, I'd run my A/C about once a month if I did that.
There is no reason to do this. Even on older vehicles the compressor should be on a circuit not hot in 'start' so it wont actually be pulled in during cranking. On modern vehicles its computer controlled so even less point.
5 miles is a bit much for me. But, what he is speaking of has nothing to do with computer control and starting. Rather drying out the condensor to reduce mold.
Originally Posted By: 79sunrunner
from spazdog "It's just to run hot dry summer air over the evaporator core for a little." Thats the same reason I shut mine off 5 miles before I reach point B while driving.
lol, I'd run my A/C about once a month if I did that.
There is no reason to do this. Even on older vehicles the compressor should be on a circuit not hot in 'start' so it wont actually be pulled in during cranking. On modern vehicles its computer controlled so even less point.
5 miles is a bit much for me. But, what he is speaking of has nothing to do with computer control and starting. Rather drying out the condensor to reduce mold.
Originally Posted By: bvance554
Originally Posted By: Colt45ws
Originally Posted By: 79sunrunner
from spazdog "It's just to run hot dry summer air over the evaporator core for a little." Thats the same reason I shut mine off 5 miles before I reach point B while driving.
lol, I'd run my A/C about once a month if I did that.
There is no reason to do this. Even on older vehicles the compressor should be on a circuit not hot in 'start' so it wont actually be pulled in during cranking. On modern vehicles its computer controlled so even less point.
5 miles is a bit much for me. But, what he is speaking of has nothing to do with computer control and starting. Rather drying out the condensor to reduce mold.
Im aware. I was talking on two different subjects. I should have specified 'no reason to do this to save the battery' or something, I guess.
Originally Posted By: Colt45ws
Originally Posted By: 79sunrunner
from spazdog "It's just to run hot dry summer air over the evaporator core for a little." Thats the same reason I shut mine off 5 miles before I reach point B while driving.
lol, I'd run my A/C about once a month if I did that.
There is no reason to do this. Even on older vehicles the compressor should be on a circuit not hot in 'start' so it wont actually be pulled in during cranking. On modern vehicles its computer controlled so even less point.
5 miles is a bit much for me. But, what he is speaking of has nothing to do with computer control and starting. Rather drying out the condensor to reduce mold.
Im aware. I was talking on two different subjects. I should have specified 'no reason to do this to save the battery' or something, I guess.
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JHZR2
Staff member
Originally Posted By: bvance554
Originally Posted By: Colt45ws
Originally Posted By: 79sunrunner
from spazdog "It's just to run hot dry summer air over the evaporator core for a little." Thats the same reason I shut mine off 5 miles before I reach point B while driving.
lol, I'd run my A/C about once a month if I did that.
There is no reason to do this. Even on older vehicles the compressor should be on a circuit not hot in 'start' so it wont actually be pulled in during cranking. On modern vehicles its computer controlled so even less point.
5 miles is a bit much for me. But, what he is speaking of has nothing to do with computer control and starting. Rather drying out the condensor to reduce mold.
I dont believe it dries the evaporator (condensor is outside) at all. The coils are cold, so they will still condense moisture when you turn off AC. Then youll have a wet environment. Unless youre in the desert, likely there is a good amount of humidity, so what will happen is youll have saturated air in the coils, because of the humidity coming in plus the moisture in the closed area. It is a very slow process to actually dry it out by flowing air, and there will always be a ton of humid air passing through.
Originally Posted By: Colt45ws
Originally Posted By: 79sunrunner
from spazdog "It's just to run hot dry summer air over the evaporator core for a little." Thats the same reason I shut mine off 5 miles before I reach point B while driving.
lol, I'd run my A/C about once a month if I did that.
There is no reason to do this. Even on older vehicles the compressor should be on a circuit not hot in 'start' so it wont actually be pulled in during cranking. On modern vehicles its computer controlled so even less point.
5 miles is a bit much for me. But, what he is speaking of has nothing to do with computer control and starting. Rather drying out the condensor to reduce mold.
I dont believe it dries the evaporator (condensor is outside) at all. The coils are cold, so they will still condense moisture when you turn off AC. Then youll have a wet environment. Unless youre in the desert, likely there is a good amount of humidity, so what will happen is youll have saturated air in the coils, because of the humidity coming in plus the moisture in the closed area. It is a very slow process to actually dry it out by flowing air, and there will always be a ton of humid air passing through.
Originally Posted By: JHZR2
Originally Posted By: bvance554
Originally Posted By: Colt45ws
Originally Posted By: 79sunrunner
from spazdog "It's just to run hot dry summer air over the evaporator core for a little." Thats the same reason I shut mine off 5 miles before I reach point B while driving.
lol, I'd run my A/C about once a month if I did that.
There is no reason to do this. Even on older vehicles the compressor should be on a circuit not hot in 'start' so it wont actually be pulled in during cranking. On modern vehicles its computer controlled so even less point.
5 miles is a bit much for me. But, what he is speaking of has nothing to do with computer control and starting. Rather drying out the condensor to reduce mold.
I dont believe it dries the evaporator (condensor is outside) at all. The coils are cold, so they will still condense moisture when you turn off AC. Then youll have a wet environment. Unless youre in the desert, likely there is a good amount of humidity, so what will happen is youll have saturated air in the coils, because of the humidity coming in plus the moisture in the closed area. It is a very slow process to actually dry it out by flowing air, and there will always be a ton of humid air passing through.
In theory, maybe, but in practice I noticed that shutting off the AC a mile or so before arriving does reduce moldy smell.
When my wife and I commuted together in our Mazda 3, I was behind the wheel most of the time and I was shutting the AC off just before arrival, unless it was really hot and humid.
Now we have two cars and Mazda 3 is my wife’s daily commuter. She never shuts off the AC and on our last trip together she even commented that the air is starting to smell moldy when AC is used, I noticed the smell too.
From experience, I think that shutting the AC off, at least in Southern Ontario, does reduce bad smells coming from the vents.
Originally Posted By: bvance554
Originally Posted By: Colt45ws
Originally Posted By: 79sunrunner
from spazdog "It's just to run hot dry summer air over the evaporator core for a little." Thats the same reason I shut mine off 5 miles before I reach point B while driving.
lol, I'd run my A/C about once a month if I did that.
There is no reason to do this. Even on older vehicles the compressor should be on a circuit not hot in 'start' so it wont actually be pulled in during cranking. On modern vehicles its computer controlled so even less point.
5 miles is a bit much for me. But, what he is speaking of has nothing to do with computer control and starting. Rather drying out the condensor to reduce mold.
I dont believe it dries the evaporator (condensor is outside) at all. The coils are cold, so they will still condense moisture when you turn off AC. Then youll have a wet environment. Unless youre in the desert, likely there is a good amount of humidity, so what will happen is youll have saturated air in the coils, because of the humidity coming in plus the moisture in the closed area. It is a very slow process to actually dry it out by flowing air, and there will always be a ton of humid air passing through.
In theory, maybe, but in practice I noticed that shutting off the AC a mile or so before arriving does reduce moldy smell.
When my wife and I commuted together in our Mazda 3, I was behind the wheel most of the time and I was shutting the AC off just before arrival, unless it was really hot and humid.
Now we have two cars and Mazda 3 is my wife’s daily commuter. She never shuts off the AC and on our last trip together she even commented that the air is starting to smell moldy when AC is used, I noticed the smell too.
From experience, I think that shutting the AC off, at least in Southern Ontario, does reduce bad smells coming from the vents.
^^^GM makes an "after run module" that cycles the fan after the engine is off to dry out the system and prevent the moldy smells. I had one installed for free at the Chevy dealer just by complaining about the smells. Surprised me that they went out of their way to do that for me. I never knew such a thing existed.
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I shut everything down when I turn the car off, but only because I'm OCD like that. I hate turning a car on and have the stereo blasting, startling the cr*p out of me, fan on full blast, wipers on, etc. it's just too much stuff going on at once. I like everything to be OFF when I start the car, then I turn things on as I need them.
Originally Posted By: Kuato
On older cars I know that the compressor would still be engaged if you left the AC on; likely on newer computer controlled vehicles they are disengaged on startup.
I like Spazdog's idea of running non conditioned air through the system on shut down; makes sense to warm it up some to reduce condensation.
My 74 Volvo didn't have the compre3ssor engaged at startup...how OLD are we talking about...back when the evap was in the TRUNK?
On older cars I know that the compressor would still be engaged if you left the AC on; likely on newer computer controlled vehicles they are disengaged on startup.
I like Spazdog's idea of running non conditioned air through the system on shut down; makes sense to warm it up some to reduce condensation.
My 74 Volvo didn't have the compre3ssor engaged at startup...how OLD are we talking about...back when the evap was in the TRUNK?
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