Problems Checking Freon Levels on 1997 Toyota Corolla

I own a 1997 Toyota Corolla in moderately good condition, but yesterday I used the A/C for the first time this year and it blew hot air. It happened before, approximately 6 years ago, and I believe there is a very slow freon leak. However, it might be something else so I purchased a can of freon that is packaged with a pressure gauge to show the existing freon levels to verify that the freon was indeed low. However, the gauge that comes with the can will not fit onto the nozzle for the 1997 Corolla. I also own a 2001 Corolla and the same gauge works fine on that car.

Do I need an adapter? Is there a different type of gauge I should look for? How do I check freon levels this car?

I am a complete DIY kind of guy. And admittedly, I have messed with A/C refrigerant. But I actually think it’s a bad idea given the expertise and tools required to properly and safely service AC systems. So first, I’m going to say that you should get the system checked out and have a shop with an AC specialist recharge the system if needed, add dye, find the leak and have the whole thing repaired.

But with regards to your question, the AC system has two ports. One is the high pressure port and you must not mess with it at all unless you are a trained professional with the right tools. The other is the low pressure port and that is the one that your DIY gauge goes on. The high pressure port is larger and the fitting will not go - and lucky for you. So my guess is that you still need to find the low pressure port.

Are you sure you’re trying to connect it to the low side port? Because it won’t connect to the high side port.


If I were you…I would take the Corolla to an independent AC shop and have the pressure checked and get your AC problem identified. Simply using a can of R-134a refrigerant with a pressure gauge is not an accurate way of determining the charge in your system. If you are trying to connect to the “high” side…you could possibly cause the can to explode and do harm to yourself in the process. When an AC system leaks down you have to first repair the leak and then vacuum the system down before adding refrigerant.

Hi/lo side ports are 2 different size. The lo side port u use for cheapo 134a fills is standard on all cars. Toyota or ford or GM. Just in different places. What does ac label say for info? 134a?

I don’t recall exactly when the shift to R134a happened - but it was prior to '97. I will say, however, that the guy who runs my local A/C specialty shop changed his personal vehicles over from R134a to R12. At least I think that’s what he did. Maybe I recall wrong and the vehicle was originally R12 and he keeps it on that as he is licensed to handle the stuff. In any case, if this is a used car I wouldn’t rule anything out.


That guy probably changed from R12 to R134a

There are plenty of inexpensive conversion kits out there . . . the service ports, for the most part

As far as I’m aware, there are no kits to convert from R134a to R12

Mechanics are supposed to be licensed to handle refrigerant and work on the systems

I am, but I know that many of my colleagues . . . past and present . . . are not

That said, the 609 license is very easy to obtain

I don’t do that anymore. Last year I was at a Walmart and a lady asked the clerk where they had the “air conditioning stuff”. He showed her the cans and she picked up a couple. Sheesh.

I’m not sure when they moved to 134a either but either you’re on the high pressure side which can blow the can up or you’ve got R12 in the system and mixing the two is not good. Back in the old days I’d dump a can of R12 in every couple years but now just take it to someone, have them check the pressure and refill properly, and add the dye in the system so you can see where the leak is. Its just not worth wrecking your compressor or getting blinded.

What I was told by a mechanic is that adding one can of R134a after six years is fairly normal, so I’m not especially worried about the leak.

Does anyone know where the low pressure port on a 1997 Corolla is located?

There’s a website to locate low pressure ports that may be handy for others who have this problem. The list is not exhaustive, but it could help.
Also this video might be useful:


I really like the dye

Even if takes months, that stuff is quite visible, provided you actually do have a leak

It’s a real time saver, in the long run

@Robk98, the low side port is typically along the passenger side fender skirt. I have seen them directly on the compressor with Toyota’s, as well.

@db4690, no. I’m quite certain that it was still on R12. That’s why I would remember it. Changing from the 12 to the 134 is routine and not worthy of note in my mind. What I am probably remembering wrong, as I noted, is that it was originally an R12 system and he has kept it that way. But I will also say that this is a shop and a guy that have been around doing auto HVAC since, I think, about the last ice age. Kit or no kit, I’m sure that if he wanted a vehicle on R12 he’d do it - even if it meant swapping an older R12 system into a newer vehicle.