What is wrong with my car's air conditioner?

You may be low on Freon due to a possible leak, See a qualified technician.

Time for a trip to the A/C shop. It’s better and cheaper for A//c to go to a auto A/c shop raather than the Auto Dealer. Unless it is under warranty.

I agree that it’s low on Freon, but the question that they need to work on is: where’s the leak?

It could be a valve not functioning well, or, some part freezing up, or a freon leak. Does it get warm when your car is idling, but blow cold again when you’re moving?

You need a recharge of the coolant…coolant fatigues over the years. Make sure you get what the OEM specs for your car (if you still can)

My guess is you need a recharge. Depending upon the car make a model it is easy to do it yourself. You can buy a kit for $20 that comes with a can of fluid (probably R-134a but check the manual for your car), the necessary fittings and a hose, It will take you 10 minutes.
Or you can pay $80 and have it done by a pro.

@Cruiser What kind of coolant are you talking about? The antifreeze or the Freon?
Antifreeze has corrosion inhibitors that break down within a year and the coolant must be replaced (or have new corrosion inhibitors added) to keep the corrosion protection up. And antifreeze doesn’t have much to do with the A/C system, especially if the engine isn’t overheating.
Freon never goes bad.
Freon can blind you since it is so cold when released from the pressurized can or system. Have a pro do the job!

@kritiper AC/coolant…putting radiator coolant in the AC system would be both foolish and near impossible to accomplish. Read the owners manual to determine what is best.

Yes. Correct. So, like I said, Freon doesn’t deteriorate (Or, as you put it, “fatigue.”). And as long as there are no mechanical problems in the system and no metallic debris, the refrigerant oil won’t go bad either.

Here’s a little known fun fact. The Freon leak spec for a certain unnamed auto manufacturer is 25 grams per year for a new unit. The system’ makeup reservoir holds 100 grams. That means you can expect to add Freon once every 4 years for a newer vehicle and more frequently for an older vehicle. Some vehicles luck out and last for a decade with no service.
Unfortunately there are no sight glass windows or dip sticks for Freon levels. Customers simply get it serviced when the system stops working correctly.

^^My old Nissan Stanza went 10 years, and never an air conditioning problem. 3 of those years, the last 3, in South Florida. I had more than one person comment to me about how well the air worked, and I never understood the fascination. I’ve never had a car air stop working (knock wood). The only air conditioner we have had to address was a used Porsche we bought that was over 20 years old.

@JLeslie Yes, it is possible to have microscopic pieces of debris actually seal small leaks resulting in a system that maintains correct levels for 10 or more years. It is also possible to win the lottery. It is just luck of the draw. We should not count on it.

I had a 1990 Nissan Sentra (bought brand new) and when it was still relatively new and under warranty, I felt the AC wasn’t as cold as it should be. I took it back to the dealer and they corrected the issue. I remember them telling me “we just charged it up a little.” I didn’t know what that really meant but I see someone above mentioned charging it, so that might be relevant.

I had a 2008 Honda Civic (also bought brand new) and I put a lot of mileage on it, with over 500 miles on it per week. At one point when it was getting up there in mileage, the AC was not working that well. I had a friend who is an HVAC mechanic (on residential and industrial, not on cars) come take a look. He got a can of freon which you can get at any auto parts store. He tried to put the freon into the car’s AC (where ever it goes). He told me if the AC doesn’t need freon, it won’t accept it. It didn’t need freon so it never came out of the can. Obviously there was something else wrong with it. Luckily the hot weather had already passed that year and the following Spring, the car went for good with over 210 miles on it. Never had a major problem which is what made me a “Honda Convert” for life. Anyway, if you get the can of freon and that’s not the problem, not much lost out of your pocket other than $20.

You can also bring it to the dealer for diagnosis for not a lot of money. It will tell you definitively what the issue is.

@jca Of course, it depends on which type of Freon your car takes. New (er) cars generally take R-134-A, old(er) cars took R-12. You can’t mix them but R-12 may be impossible to find or very expensive.
A A/C system can take more than what’s required, it just depends on how hot the can is. The hotter the can, the higher the pressure, the more will go into the car. A pro knows when it’s full (by his/her pressure gauges) and won’t put in too much. And some systems do have sight glasses.

Thanks, all.