Car AC Not Blowing Cold Enough
Car Airconditioning Compressor
I get a lot of questions about car air conditioning systems not blowing cold enough. Especially during hot humid summer days. Most people would like to see frigid cold air blasting from their small dash vents instantly upon request.
Remember when your car has been baking in the sun heat is stored up in large quantities and must be removed before it starts to feel cool inside. But what if the air does not seem to get cold after 5 minutes or so?
There are many factors involved that affect the actual output temperature at the dash AC vents. To follow will be a few examples of common problems that I find when inspecting a car air conditioning system that is not performing as well as it should be.
Without a doubt the most common problem that I find is an incorrect Freon charge. The amount of Freon in the system is extremely critical. The manufacturer installs the exact amount that is required for the system to perform at its peak. This exact charge is so critical it is documented in the vehicle’s engine compartment down to the ounce.
A few ounces short of a full charge can result in inadequate cooling under high heat loads due to lack of reserve refrigerant. A telltale sign of this condition would be for a compressor clutch to cycle on and off faster than usual. The rapid clicking sound generated from this condition can usually be heard from inside the vehicle.
Sometimes when people try to recharge their system on their own they will actually overcharge the system which can cause poor cooling performance just as much as low Freon levels. In extreme examples an overcharge of refrigerant can even cause AC compressor damage and noisy operation.
Loss of AC efficiency
Car AC Condensor
Not as common as the Freon issue mentioned above but one that is common in my area at this time of the year is a radiator or a condenser that has been considerably clogged with bugs, dust and dirt, or road debris and trash.
When this junk starts to reduce the airflow that passes through the radiator and then through the condenser it can cause higher than normal high-pressure readings. This in turn can knock several degrees off of the output temperature in the interior cabin.
This is the kind of problem that slowly gets worse over time. It is very rare that people will take the time to check or clean the radiator and condenser. The fleet company I work for has made this operation part of the scheduled service operations. We have a pressure washer and we physically clean the radiator and condenser fins every 20,000 miles.
AC Test Guages
Although there are lots of other problems that can cause poor cooling the two mentioned above are ones that I find often. If you think your car air conditioning is not blowing cold enough the first step is to check the output temperature at the center duct with a thermometer.
Make sure the recirculation or max air mode is selected and the blower is on low speed. 40 – 50 degrees is perfect. On hot humid days here in south Florida 55 degrees is welcomed. Step 2 is to have a professional connect a manifold gauge set and get some high and low side pressure readings. With these readings a logical path of diagnosis can get your AC blowing cold as it should be.
I put together a repair modules section on my you fix cars website that talks about the theory and operation of car air conditioning. Understanding how the system works is very helpful for problem solving. You can also head back to this blog’s main page and get some more automotive repair information.
Mark Gittelman is an ASE Certified Automotive Master Technician With more than 26 years experience in the auto repair field. See Mark's Car Repair Credentials and Work History on Google+.
Dar Dsa: Very slow Freon leaks are the hardest ac repair to resolve. A 2003 Honda Civic does not hold much freon to begin with. If it takes 2 years to leak out this is a very very slow and hard to detect leak. I would give the shop that installed the dye another shot. If they did install the dye correctly there may be a chance they can detect the location at this time. It boils down to equipment and techniques used to locate the leak by the shop. Finding someone with the skills, equipment and patience to bear down and fix your problem will be challenging.
Hi Mark – appreciate your time and advise. My Honda Civic 2003 LX AC has every 2 years stopped putting out cold air. While it was under warranty the dealer replaced the O-ring and the AC blew cold air. 2 summer later (when the warranty had lapsed 6 months) it was again not blowing cold air. Honda agreed to pay for parts $60 if i paid for labour $200. This time they replaced a valve. 2 years later again it was not blowing cold air. this time i took it to an independent shop. they told me they could detect no leak with dye and UV, recharged the system and sent me on my way (and a $300 bill). the system blew cold air that summer and the next but again this past summer it was no longer blowing cold air. I dont want to spend another $300 to be no better off than before. Any advise on what the problem might be or am i better off just re-charging the system every 2 years?
I have a 2008 ford fusion that I can start 15 to 20 minutes before I need to leave for work. but when I come back out it is still cold and still frosted. then when I begin driving it begins heating up. doesn’t do it every time.
Roman: In the end you will need some hands on diagnosis. But I can say I have seen blend door control motor problems on some of the 2002 Chevy models that have symptoms similar to what you described. The GM dealer can test these motors with specialized equipment making them the best place to go for quick answers to problems such as yours.
Mark,
I have a 2002 Chevy 2500 Duramax. The AC when on max cold only gets cool. If I change to temp setting only one click toward the heat, still well within the cold air setting, it starts blowing hot air. I have take then housing off below the dash and it seems to be blowing cold air but changes to hot as soon as I make the same temp setting change on the AC controls. Is there some kind of “door” that is not moving or could you give me some other advice.
Thanks,
Roman
Hi Mark,
2006 F150 Crew cab with 90,000 on it. A/C works great 95% of the time. Usually gets down to 42-44 while driving. The problem I have usually occurs right after starting the engine or within 10-15 minutes of an engine start and only occurs at idle/low RPMs. The air will cycle hot cold hot cold until i start driving. I’ve been to 4 shops (2 dealerships and 2 neighborhood shops) over the last 12 months trying to get it fixed and no one can figure out why. The funny thing of it is that right after they’ve supposedly “fixed it” the car usually sits outside the shop in the hot sun, I go pick up the car and voila, the issue happens right on the spot before i even leave the parking spot. The guys who worked on it are dumbfounded and after a couple days of trying to find out the issue they usually just give up and call me to come pick the truck back up. I’ve had the clutch replaced, system recharged twice, condenser and manifold lines replaced. The times the problem rears its ugly head is usually if I just sit in park after the car has been in hot sun. It will start blowing cool air, then click off and blow hot, then click on and blow cool again etc etc etc till i start driving down the road. The other usual cause is if it’s been sititng in hot sun for a while and I go for a quick trip to a drive thru (less than a 5 minute drive away) it will do its on off on off stuff while i sit in the drive thru. Everything checks out at the moment from pressures to no leaks etc (according to the shops anyway), yet I can still reproduce the problem on a regular basis (provided the hot weather is available). Everyone’s first diagnosis is either the clutch or low pressure, but both of those have been addressed. At first I was kinda pissed because of the time and money lost, but now this has turned into something kind of amusing watching everyone scratching their heads at my perdicament. Any help or suggestions would be much appreciated.
I changed my ac compressor about 5 times because everytime i changed it, it would get clogged. But they finally fixed it. However, my ac was still blowing hot. So I was told that my radiator is probably not doing a good job in cooling my engine as air does pass through the radiator to cool it down. And i knew my radiator was old, and it actually had a little leak. But once I replace my radiator……BOOM! AC IS BACK TO BLOWING COLD AGAIN!
My ’96 Ranger is now blowing only hot air. For the past month or so it blowed cool air at low speeds but hot air on the highway. I just tried to charge it with r-134, but saw that the pressure was a bit over normal. I see cold sweat on the valves out of the evaporator. Does it sound like the compressor/condensor, or more like a clog in the system? The compressor runs continuously and does not cycle when the A/C is turned on. I live in 100 degree weather. Thanks.
I’ve got a 2010 Ford Fusion, 44k miles, has dual auto-temp conrols. AC temp out of the center registers was around 58-60 degrees, outside temp 95 and humid.. my 94 Taurus and 99 Taurus both blow at 38-42 degrees same outside temp. 99 has auto-temp, 94 is manual.. dealer replaced compressor and associated part on 2010 Fusion, said compressor was failing??? New parts still work like old parts, temp is basically the same 58-60. On a cooler day, register temps will be lower down near 50. This car came from the Carolinas, was actually used by Ford rep, ran between Carolinas and Georgia.. car is otherwisw in pristine conditon. Any ideas???
Thank you
Thanks Mark, the readings low side was 30 and the high side was around 350-400 I thought that meant it was over charged but the shop said that it is not.. But also it did something else to that I forgot to mention it has a pressure release valve on the compressor and it released freon I heard it do it..
Virginia: Hard to make a call on your problem without hands on diagnosis and pressure readings. The shop should be able to determine an electrical problem from a freon or system problem. I can say that the most common thing I find after replacing a car AC Compressor and have these kinds of problems, is clogging of the orifice tube on GM cars.
This comes from improper flushing procedures. Vacuuming down the system is not good enough with an internal compressor failure, you need a liquid AC flushing chemical. As for not being able to reproduce or solve the problem it would seem you need to physically drive with the mechanic. Take him out on highway 95 and make him sweat! No mechanic should give up when the going gets tough.
Hello, Mark I have a 93 Chevy camaro and the A/C was working fine and then the compressor went out on it, I then had the compressor replaced , had a shop vac the system down and then they added freon, it worked great for one day and then now this is what it is doing… When you start the car the a/c works great then when you start to drive it above 35mph it will stop blowing cool air, (it still blows just not cold) the freon is not low had it checked by two different places.. But I don’t think it is freezing up because when the are is working it will get condensation on the line.. Plus, I can turn the a/c off and then shut the car off and start it right back up immediately and turn a/c on and it will work fine again until I start to drive over 35mph .. (not exactly at 35mph) but normally. I have also tried just turning the a/c off and back on with out shutting car off and it does not change. Have also tried turn car off with the a/c still on and starting the car back up and it still blows warm air. The only way it will start blowing cold air is to turn the a/c off and then the shut the car off and the restart …Its kinda strange to me and I have already spent a lot of money on trying to get some a/c in my car.. Do you know what it could be I have been to several shops and I just don’t think they know that much about a/c to be an a/c shop. please help. Its really hot here in Florida and I am in my car all day.
Dan: “Does not get cold until I am on the highway” This could be an indication of a condenser fan problem but other issues can cause these symptoms as well. As for the temperature control issue I have seen both control head problems as well as temperature blend door actuator motor failures on the early 2000 model GM trucks. A diagnostic at a GM dealership might be the best way to go for answers to both problems.
Aaron: “simply add freon to the car or does one really need to vacuum the existing refrigerant before adding Freon” The total installed charge is so important for proper cooling that it’s recommended to recover all remaining freon from the system and then install the exact required amount. The problem with just adding freon is you don’t really know how much is still in there. Also the single serve cans usually come in 12 or 16 ounce. That could put you over and reduce the output temperature and or damage the compressor in some cases.
Does not get cold until I am on the highway, city driving it never gets cold. I have a 2001 Chevy Tahoe.
Is this a condenser or recharge issue?That is besides the problem that whatever position the thermostat is in HOT or COLD, that is what you get no matter how you turn it. To get the air to change temperature I have to turn the car off and then change the thermostat to what i want and then restart. I believe this is a control board problem but am reluctant to spend the $250 and find out I am wrong, thoughts?
Mark,
My 2005 Toyota Camry recently began showing signs of not blowing cold air like my other vehicle (which happens to be a 2001 F150 that has not had problems with the AC) . I’m thinking a recharge could possibly fix the problem (of course if it later begins to blow cool air again, then the system could be leaking). What I’m wanting to know is: Can one just simply add freon to the car or does one really need to vacuum the existing refrigerant before adding Freon? Im trying to find the quickest possible way to fix this problem on my own. Also, is there such a thing as a filter for your ac (somewhere in your compressor?) or is the only “air” filter the main cabin air filter? I appreciate your time and greatly appreciate your response.
Sara: If I understand correctly the ac was charged and is now okay. If this is the case see how long it lasts. This can be an indication of how bad the leak is. Over all it seems that a third opinion is in order. Ask friends and neighbors and co-workers for a recommendation. Make sure to notify the shop that you are there because so and so recommended them. Repair shops are less willing to loose 2 or 3 customers at one time.
Hi Mark,
My car is not cooling enough the mechanic from the dealership told me I have a leak in my compressor. Took my car to another shop the mechanic can’t tell if i have a problem with a leaking compressor or the hose! then I requested to get a freon charge then my car was cooling again like it was used to. What should I do? I’m confuse I don’t know if my car really has a leak or both shop just wanted to rip me off . Or my car just really needed a freon charge.
Hi Robyn, that usually happens because of a malfunctioning blend door that controls the hot and cold air mixture. Usually a simple fix.
Thank you for this article! It saved me a diagnostic fee at the very least. My vehicle has 82k miles and the AC does not blow as cold as my wife’s newer vehicle, which can be a problem with the 100F+ Texas heat. I took your temperature testing range, grabbed my meat thermometer and ran some tests. I used various fan speeds and recirculation settings, and saw the temperature was within range. I noticed the temperature increasing during my tests so I decided to drive around and get some air flowing over the condenser. Wow what a difference that made! My vehicle only has a small fan that covers maybe 15% of the condenser and the vent temperature would rise quite fast at stop lights even with the engine radiator fan running. I used to think higher engine speed made colder air, but that was not the case. I also got my oil changed just before this test and finally gave in and let them replace the in-cabin micro filter for $85. I am comfortable that my a/c system is running well with the new filter and knowledge of how it works.
What if it only blows cold air out on ONE side of the car? The driver side has perfect cold air but the passenger and back seat vents have hot/warm air. Any clue? My dealership (without actually looking but just giving them this info) said they would have NO idea why this would happen. If a dealership has no idea, who is going to?