Any at home tests for car AC?

[badatmath]

I'm thinking like "stick a thermometer in the vent" or something super super simple.

It is running around 118 outside and IDK what is reasonable to expect to cool off a car that has been in the sun for 2 hours so I don't feel super inclined to go spend $300 on diagnostics if I am just being cranky. I have been driving way more lately on short trips so it could be me but my neighbors are like it only takes 2 minutes to cool the car. Um not mine.

It blows cool-ish air at a good rate but not what I'd call cold for some time. Usually farther than I need to drive to get home. I sorta think it might be my expectations being off but it could be developing an issue too.

No leaks of anything alarming have showed up on the garage floor.

I don't have a trusted mechanic so I will have to hope good reviews are right if I need to pick a shop.

I kind of assumed they typically failed in a huge obvious way but I realized I have no idea as I have not ever had a problem with one.

 

[aja8888]

Leaks are freon gas (or equivalent) and vanish so you won't see anything on the garage floor. The best way to test the A/C is with a set of gauges (hi and low pressure sides). Low freon will eventually make the A/C cycle (cool/warm) or not come on at all. If you have a leak, the pressure test will reveal it. Then the tech can use a sniff tool to try to find it. Worst case is they use a dye and a black light to find leaks.

Stick a thermometer in the vent and see what you get . It should be somewhere around 40 - 50 F if it's working well.

There is no free lunch with A/C units.

 

[Time2]

I'm thinking like "stick a thermometer in the vent" or something super super simple.

It is running around 118 outside and IDK what is reasonable to expect to cool off a car that has been in the sun for 2 hours so I don't feel super inclined to go spend $300 on diagnostics if I am just being cranky. I have been driving way more lately on short trips so it could be me but my neighbors are like it only takes 2 minutes to cool the car. Um not mine.

It blows cool-ish air at a good rate but not what I'd call cold for some time. Usually farther than I need to drive to get home. I sorta think it might be my expectations being off but it could be developing an issue too.

No leaks of anything alarming have showed up on the garage floor.

I don't have a trusted mechanic so I will have to hope good reviews are right if I need to pick a shop.

I kind of assumed they typically failed in a huge obvious way but I realized I have no idea as I have not ever had a problem with one.

I have read you can expect near a 25*f difference between intake and output temperature on a car air conditioner. I don't know what difference that extreme 118*F will make to that. Now, I did a search and I see this;
Taking into account 50-60 % relative humidity and a 77 F,
86 F, 95 F, ambient air temperature, the discharge air temperature at the center vent should be in the range of :50-54 F that's 23* to 27* difference.

56-60 F that's 26* to 30* difference.
63-70 F that's 25* to 32* difference.
That's with blower on high and a list of other conditions (which I would would probably ignore, but that's me)



https://autoacrepair1.com/how-cold-should-my-ac-be-at-the-vent-in-my-car/

 

[badatmath]

Thanks guys. I did find a promising write up that I am currently trying to read through that I will add here in case some future searcher has this question too. https://aa1car.com/library/ac98.htm

Editing to add according to the weather our humidity right now is 15% . . . /sigh. I will text a guy from w*rk that might have some gauges too.

 

[Walt34]

The type of car can make a difference too. My 2003 GMC pickup truck has that big flat grille, which makes for lousy gas mileage (18 mpg on a good day) but the plus side is that it leaves room for a gigunda size A/C condenser right behind that grille. The A/C in that truck will give you frostbite on a 100° day. Okay, it's not quite that good, but close. I very rarely run the A/C on high, and if so not for more than a few minutes.

The newer 2014 Honda Accord is much more streamlined and has a sloping hood which is great for gas mileage but it doesn't leave much room behind the grille for the A/C condenser, which is a wimpy little thing and it takes the A/C in that car quite a bit longer to get the inside comfortably cool on a hot day. It will do it eventually but the difference between the A/C on the Honda and the GMC truck is dramatic, which I attribute to the noticeably larger condenser in the truck.

It is so noticeable that on the hottest days if we are both going out we'll take the truck because the A/C in it is so much better than the car.

 

[njhowie]

Go to Walmart and pick up a can of AC Pro. Easy to use, simple instructions. Has the gauge and hose attached. Anyone can do it. I used it two or three years ago and AC is still blowing cold, no issues.

 

[aja8888]

Thanks guys. I did find a promising write up that I am currently trying to read through that I will add here in case some future searcher has this question too. https://aa1car.com/library/ac98.htm

Good luck! And we know the only time A/C's fail is when you need them the most, even home units.

 

[HarveyS]

Go to Walmart and pick up a can of AC Pro. Easy to use, simple instructions. Has the gauge and hose attached. Anyone can do it. I used it two or three years ago and AC is still blowing cold, no issues.

+1

 

[badatmath]

Yeah I have AC on the brain hoping my home AC does not fail right now in this heat wave. It seems to be chugging along fine so far but it is 25 . . .

 

[freedomatlast]

Use the recirculation mode if not doing so already in 118ºF heat.

 

[Time2]

My 2003 GMC pickup truck has that big flat grille, which makes for lousy gas mileage (18 mpg on a good day) but the plus side is that it leaves room for a gigunda size A/C condenser right behind that grille. The A/C in that truck will give you frostbite on a 100° day. Okay, it's not quite that good, but close. I very rarely run the A/C on high, and if so not for more than a few minutes.

We have a 2005 GMC cargo van that we previously used in a business. Because of the nature of the business, when I got it, I built out the inside and had it spray foamed and nicely paneled. That van is the coldest in town!

 

[tfudtuckerpucker]

Another option is one of these videos. Personally I prefer Scotty.

 

[gauss]

At least there is no capacitor to go bad in an auto a/c unit.

-gauss

 

[EarlyandLate]

Use the recirculation mode if not doing so already in 118ºF heat.

Yep, try the recirculate. If that doesn't do it you may need to recharge as suggested above. I did it on my 2004 Honda Accord and it was one of the simplest things I have ever done to a car's mechanicals. Worked like a charm.

 

[JoeWras]

Other dumb stuff has to be considered. Stuck blend doors can mix heat in. Control units can run hot.

My 2011 Honda Odyssey Touring is too smart for itself. This was top of the line back then. It has humidity and solar sensors. It knows the latitude and date. Based on all this, it will sometimes act on its own, despite the setting. People complained and they made it dumber in following years.

 

[badatmath]

Other dumb stuff has to be considered. Stuck blend doors can mix heat in. Control units can run hot.

My 2011 Honda Odyssey Touring is too smart for itself. This was top of the line back then. It has humidity and solar sensors. It knows the latitude and date. Based on all this, it will sometimes act on its own, despite the setting. People complained and they made it dumber in following years.

Kinda funny! It is just too hot to spend much time poking at it even if I knew what I was doing. Tomorrow I will try to decide if it is just a "me" problem. Which I sort of suspect so. Normally we don't run quite so hot around here.

 

[ERD50]

Kinda funny! It is just too hot to spend much time poking at it even if I knew what I was doing. Tomorrow I will try to decide if it is just a "me" problem. Which I sort of suspect so. Normally we don't run quite so hot around here.

Don't forget - to get a hot car cooled down quickly, open the windows for a couple minutes with the fan on HIGH and NOT on recirculate - this helps blow the hot air out.

Then close the windows, put it on recirculate, and as it gets a bit cooler, lower the fan speed to get colder air circulating.

On one of my cars, it was noticeable that when you got moving to 35+ mph, the AC got significantly cooler. The outside unit needed some air flow to dissipate the heat. Sitting still, the A/C wasn't as effective.

If you've done all that, and it still seems marginal, follow the other checks. But give it a chance to work by helping it with the above tips.

-ERD50

 

[Montecfo]

Just from your comments OP I think we can surmise your AC will need repair. So may want to begin shopping for a good independent mechanic.

I like to ask their shop labor rate. It is a decent proxy for how expensive they will be.

 

[The Cosmic Avenger]

I like my IR thermometer, I picked one up a few years ago for under $20. I would probably point that into a vent before I start the car, then check the temp in there every so often to see if it is cooling down. It will measure the temp of the surface, not the air, but inside the vent you should see it dropping more quickly than in the passenger compartment, where it might not feel noticeable.

But I agree, it's probably time to recharge it, either yourself or professionally.

 

[badatmath]

I got new priorities for the day for storm cleanup! Ugh.

I haven't found any serious damage unlike the neighbors.

 

[skyking1]

I just wanted to add that many systems on newer vehicles will put a pressure reading into the OBD2.
My ram truck does that. You can hook up an OBD2 scanner that will pick up the high and low side pressures. It's a pretty cheap diagnostic tool to have.
The same system will allow me to read my fan speed on the cooling fan and see that that part of the system is working as intended.
It's not as invasive as putting on a gauge set and you can do it when you're going down the road with one of those Bluetooth scanners.

 

[Piper20]

Normally there is a site glass on top of the Freon filter dryer. After the AC has run for a few minutes there should not be any bubbles in the site glass. If there are bubbles you’re low on Freon.

 

[RetMD21]

I see guys on youtube sticking dial type meat thermometers in thee ac vents. I imagine that the cooling that works at 85 isn't going to be very satisfying at 118

I am guessing that a lot of people don't change their cabin air filters as recommended and that can affect cooling

 

[badatmath]

Yeah cabin air filter was my first thought but it isn't very old and I barely drove last year since WFH.

 

[SJhawkins]

I just wanted to add that many systems on newer vehicles will put a pressure reading into the OBD2.
My ram truck does that. You can hook up an OBD2 scanner that will pick up the high and low side pressures. It's a pretty cheap diagnostic tool to have.
The same system will allow me to read my fan speed on the cooling fan and see that that part of the system is working as intended.
It's not as invasive as putting on a gauge set and you can do it when you're going down the road with one of those Bluetooth scanners.

Thanks for this, I need to look into this more. I have a set of gages but I like this idea too, much faster and easier.