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AC cold when driving, warm while idle/stopped

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Old 04-11-2015
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AC cold when driving, warm while idle/stopped

Hello,

I have a 2001 Civic 4 Door EX, 100k miles. Recently just noticed that my AC is cool at idle/stopped but gets immediately cold when I start driving(say after a stop light).

Does anyone have an idea what might be the cause? Of note, I just brought it to the dealer and they checked the AC saying it needed to have the Freon flushed/charged for 200 dollars. I did not have(or at least notice any AC problems until I brought it to the dealer). Could checking the AC have caused this problem by letting out coolant?

Thanks for any input.
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Old 04-11-2015
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Re: AC cold when driving, warm while idle/stopped

If the system is low on refrigerant then it could cause the temp to fluctuate. I would get it charged and see if it helps. It gets colder as you move because the compressor is spinning faster so it is able to move what refrigerant you have through the system better.
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Old 04-20-2015
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Re: AC cold when driving, warm while idle/stopped

Hello TXcivic2001ex,
has your car over heated?? because if it had you many have a blown head gasket it. I recently brought a 2001 civic on craigslist and one of the first things I noticed was the car would blow cold air when stopped at a light and hot when i was driving then it overheated a few times headgasket job cost me $900. But it could just be your cooling system that might have a leak that's a cheaper fix.
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Old 04-21-2015
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Re: AC cold when driving, warm while idle/stopped

Heat and AC are 2 different critters. Yes, low freon is a possible cause of those symptoms, also make sure both your fans are turning when the AC is on at idle. These things don't hold much freon...
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Old 04-21-2015
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Re: AC cold when driving, warm while idle/stopped

thanks for the replies.

Yes, both fans behind the radiator turn on and off when I push the AC button on and off. The compressor also spins likewise when I switch the AC button on and off. While in park, I step on the gas to rev the engine and it immediately starts blowing cold. Kind of weird.

It's just that I never had this problem until I took my car to the dealer for an oil change and they checked it. Could checking the pressures have let some coolant out causing this problem now? Would they have had to let out a lot because obviously it is still cold when the engine is more than idle.
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Old 04-21-2015
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Re: AC cold when driving, warm while idle/stopped

It's just that I never had this problem until I took my car to the dealer for an oil change and they checked it. Could checking the pressures have let some coolant out causing this problem now? Would they have had to let out a lot because

IF they connected a machine to do any pressure tests, it's POSSIBLE it could have let enough freon (refrigerant, R134a) out of your system to make a noticeable difference.

It takes a certain amount of freon to fill the empty hoses of the test equipment, and when the car uses such a small AC system there is not much room for error, and any loss of refrigerant could be noticed. If the system only holds less than a pound of freon to begin with, a loss of just a couple ounces starts to affect system efficiency in a noticeable way.

Did you get a printout (or anything) showing AC system pressure readings that were taken during the test? If not, good luck getting anyone to admit a machine was connected, or do anything about the problem for free..

and they checked it.
Did you request the AC be "checked"?
If the AC blows cold and works correctly, I would not pay to have it "checked". Turn it on and use it.
Save your money for when there is a problem.
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Old 05-30-2015
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Re: AC cold when driving, warm while idle/stopped

UPDATE:

Had the freon recharged and dye test. No leak, they said it was 1/2 lb low on coolant. A little better after filling it up. AC is still much colder when driving than when idle. Cool when idle, pure cold when driving or when I push the gas when in park (immediately gets cold).

Any ideas what could be the problem? Perhaps the compressor going bad? Any way to check that? I bet thats pricey to replace.

Any idea what could be causing
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Old 05-30-2015
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Re: AC cold when driving, warm while idle/stopped

Cool when idle, pure cold when driving or when I push the gas when in park (immediately gets cold).
That's kinda typical, but I can't tell you if you still need the freon level tweaked a bit more, or if you have a real problem, or not.

PLUS your system apparently has a leak that hasn't been found and repaired as of yet.
You can't really tell how rapid this leakage is yet, it may be slowly leaking out?


When I charge a system I use the higher weight spec on the underhood info label.


An AC system is less efficient when the compressor RPM is slow.
When doing an AC performance test we are supposed to keep the engine RPM at 1500-2000 during the testing, because the systems are not real efficient at idle.

AC efficiency increases quite a bit as RPM is raised and airflow through the condensor increases (airflow increases with road speed)
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Old 05-30-2015
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Re: AC cold when driving, warm while idle/stopped

What do you mean by "higher weight spec"? More PSI depending on the outside temperature?

They said the if the problem isn't fixed, to bring it back and they will run the UV light again to look for a slow leak that wasn't there the first time. The thing is, I had it filled yesterday and this afternoon the car was doing basically the same thing as before the recharge however the temp when idle is a little cooler now.

This whole thing started until I noticed a sound a slight vibration when the AC was on. It worked completely fine at idle and at speed though. I told the dealer when getting my oil changed and they said the coolant was low when they checked it. While driving home from the dealer I started noticing that the car wasn't blowing cold unless I was driving. Any thoughts?
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Old 05-30-2015
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Re: AC cold when driving, warm while idle/stopped

What do you mean by "higher weight spec"?
If you find the AC label somewhere in the engine compartment, it will probably give a weight range for the freon charge. Example would be something like 0.50kg-0.55kg

More PSI depending on the outside temperature?
Freon is measured by weight. Ounces, pounds, grams, kilograms. AC machines use an electronic scale and charge by the weight of the freon. Temperature is not a factor in this part.

Operating pressures will vary widely with temperature, heat loads and other system variables though.
They said the if the problem isn't fixed, to bring it back and they will run the UV light again to look for a slow leak that wasn't there the first time
Yep. It has to be in operation to get the dye circulating, and it needs to have time to leak while in use before any dye would be found on the outside of the system parts or fittings. It could take days, weeks or months depending on the size of the leak.
And water or rain can sometimes rinse away some of the dye evidence and make it real difficult to find.

The thing is, I had it filled yesterday and this afternoon the car was doing basically the same thing as before the recharge however the temp when idle is a little cooler now.
Could still be a bit undercharged, or there could be a problem. I'd kind of expect that if it cooled good before but not now, it's still a bit low?

An experienced pro should be able to diagnose most of it by watching the pressures.

The AC machines are designed to be simple enough that almost anyone in the shop can successfully recharge an AC system, and that might get 90% of the cars cold again for a while. But when there's a real problem with a system, most of those kids are just lost.

The AC machine can't diagnose problems by itself.
This whole thing started until I noticed a sound a slight vibration when the AC was on. It worked completely fine at idle and at speed though.
I didn't see that in your post before.
Vibration issue?
Or is it a noise issue?

Is it still an issue now?

and they said the coolant was low when they checked it.
Terminology problem here?

Coolant = antifreeze = radiator
Freon = refrigerant = AC system

What system did they check if you asked about coolant?




Oh damn, I might be mixing up replies for different threads. Sorry.
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Old 05-31-2015
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Re: AC cold when driving, warm while idle/stopped

This whole thing started when I noticed a slight tapping sound when the AC was on. I turn on AC, noise starts. Turn off AC, noise stops, even if the fan is still blowing. I took it to a different Honda dealer and they diagnosed it as a worn left and front engine mounts and but also said my AC needed to be recharged. My car since has been not cooling well at idle but blowing cold at higher RPMS. The system also did not cool when it got really hot. Occasionally on the highway it would intermittently go warm and cold even with continuous driving.

I took it to different dealer on Friday who said it was low and needed to be recharged. They said the front engine mount needed to be replaced but the left one was completely fine. The first dealer even had me feel the space to show that the left front one was worn and causing the tapping sound. I did not have either of the engine mounts replaced due to the discrepancy in diagnoses.

After reading on the internet, it sounds like the whole problem with the noise and AC function maybe from the compressor going bad? What do you guys think?

http://www.ehow.com/how_10036687_tel...t-vehicle.html
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Old 05-31-2015
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Re: AC cold when driving, warm while idle/stopped

is there a way to test the compressor function? Should either dealer have picked up on this the first time? When replacing the compressor, does the system need to be recharged? Do shops charge for recharging the system when replacing the compressor?
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Old 05-31-2015
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Re: AC cold when driving, warm while idle/stopped

My car since has been not cooling well at idle but blowing cold at higher RPMS. The system also did not cool when it got really hot. Occasionally on the highway it would intermittently go warm and cold even with continuous driving.



I took it to different dealer on Friday who said it was low and needed to be recharged.
So did they recharge it? That's a whole lot cheaper than replacing the compressor needlessly.
This whole thing started when I noticed a slight tapping sound when the AC was on.
A failing compressor generally won't make slight noises. It's usually a constant continuous buzz or growl that would vary speed and intensity with engine RPM, and come and go as the compressor cycles on and off.

Use a stethoscope to listen for noise source.
Long screwdriver, long wooden dowel, or a rubber hose held to your ear.

If the compressor is real noisy, it should be obvious through a stethoscope. (Compressors make noise anyway, they are not exactly quiet when in operation.)

Something loose can make a lot of noise too, like maybe a loose alternator bolt? Stethoscope.

If a motor mount has collapsed causing vibration, you can gently raise the engine a little bit with a floor jack and probably feel the difference through the body of the car.

is there a way to test the compressor function?
As I said earlier, pressure gauge readings and experience.
Should either dealer have picked up on this the first time?
Maybe, maybe not.
See earlier explanation about "the machine".
When replacing the compressor, does the system need to be recharged?
Of course.
Do shops charge for recharging the system when replacing the compressor?
Of course.
It may be rolled in to the price, or it may be a separate line, but it's there.

After reading on the internet
Heellllllooooo!!!
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Old 05-31-2015
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Re: AC cold when driving, warm while idle/stopped

Thanks for the comments.

Yes, they recharged it on Friday and did the dye test. No leak was found but nothing has really changed since they recharged it. Still cool when idle/low rpms and pure cold when driving or at higher RPMS.

I'll call them tomorrow and see what they say.

Regarding the motor mounts, should it not be pretty obvious if one needs to be replaced or not? Does it seem weird for one dealer to say the left and front need to be changed but another dealer say the left is fine but the front needs to be changed?
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Old 05-31-2015
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Re: AC cold when driving, warm while idle/stopped

Yes, they recharged it on Friday and did the dye test. No leak was found but nothing has really changed since they recharged it. Still cool when idle/low rpms and pure cold when driving or at higher RPMS.
I thought you have had two different shops check this out.


Regarding the motor mounts, should it not be pretty obvious if one needs to be replaced or not? Does it seem weird for one dealer to say the left and front need to be changed but another dealer say the left is fine but the front needs to be changed?
No they aren't always obvious.

Terminology may be an issue. Front of the car, or front of the engine? Big difference. Even my service manager doesn't get this one correct most of the time.
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Old 05-31-2015
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Re: AC cold when driving, warm while idle/stopped

Yes, I did bring it to two dealerships. Didn't have any work done at the first one other than an oil change. Was going to have it all done when my airbag recall gets in stock but ended going to a different shop closer to where I work.

Ok. The first shop printed out the price quotes for front and left engine mounts. The 2nd shop said only the front needed to be changed. Even after I told them the another shop said both needed to be changed.

Inconsistencies between the two dealerships in what needs to be/not needs to be fixed make me skeptical. That's why I'm trying to figure out what maybe wrong with my AC still not working properly after recharging. The car is 14 years old and never did this before especially when I lived in Texas the first 10 years. First AC problem of the car.
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Old 09-19-2016
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Re: AC cold when driving, warm while idle/stopped

Hi!

I have the same problem with my 2007 Civic, A/C runs properly or better when the car is not on idle or if its a cold day but when you stop it blows out warm air. Both fans are working, compressor is running when you turn the A/C on. Would a simple recharge fix the issue?

I was thinking of getting one of these, Interdynamics AFK-11CS Arctic Freeze Ultra Synthetic Recharging Kit with UV Dye and UV Light to fix the issue, do you guys think its a good idea to try it rather than go to the dealer? or is there a better product I could use for a recharge?

Thanks!
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Old 09-19-2016
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Re: AC cold when driving, warm while idle/stopped

Use plain R134A, with UV dye.
If you ever have to take it to a shop that cares about their equipment and you don't have the correct refrigerant in the system, you may be sent away.



You can buy a blacklight later on if you need to. If the system has a really slow leak it may take years before it leaks enough to be noticeable (you'll have lost the light by then LOL). You'll know when it doesn't cool right again, then you can start looking.

The system is quite small, it is very easy to overcharge it and cause more problems than you started with, and by the time you can see it on the little gauge they gave you, it's too late.
I'd add just a little bit at a time, and check vent temps after each little burp of freon added. Quit adding when it gets cold air out of the vents.
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Old 09-26-2016
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Re: AC cold when driving, warm while idle/stopped

Originally Posted by ezone View Post
Use plain R134A, with UV dye.
If you ever have to take it to a shop that cares about their equipment and you don't have the correct refrigerant in the system, you may be sent away.



You can buy a blacklight later on if you need to. If the system has a really slow leak it may take years before it leaks enough to be noticeable (you'll have lost the light by then LOL). You'll know when it doesn't cool right again, then you can start looking.

The system is quite small, it is very easy to overcharge it and cause more problems than you started with, and by the time you can see it on the little gauge they gave you, it's too late.
I'd add just a little bit at a time, and check vent temps after each little burp of freon added. Quit adding when it gets cold air out of the vents.
Is there a plain R-134A with a UV dye that you can recommend?

The one I have is saying R-134A+ on the can, apparently people are saying there is something added to it because of the "+". The one i bought has a black light included with it.
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Old 09-26-2016
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Re: AC cold when driving, warm while idle/stopped

Originally Posted by tlim9146 View Post
Is there a plain R-134A with a UV dye that you can recommend?
Consumer level? No.
You have to check product yourself. Make sure it really is the correct product in the can, nothing other, nothing else.

I was scared of the long fancy expensive sounding name "Interdynamics AFK-11CS Arctic Freeze Ultra Synthetic"

No need to pay extra for fancy words. It only needs to be R134a with UV dye.


The one I have is saying R-134A+ on the can, apparently people are saying there is something added to it because of the "+". .
What's the plus mean?

Read the back of the can.
R134a is
1,1,1,2-Tetrafluoroethane
Formula: CH2FCF3

Plus the UV dye, which may be described along with some oil, hopefully a PAG type of oil.
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