Hey All
I am a new to me Fit owner and have been experiencing issues with my AC. I have searched this forum and could not find an exact answer so I hope someone could help me diagnose what's wrong or where I should start.

Day 1 - AC blows warm. I thought I checked everything when I bought the car used, turns out I did except something so simple as the AC. Dumb mistake but I am living with it now! The rest is solid and couldn't be happier!

I charged the system with R12 canned stuff and system blows cold. It still does however the issue is that when I run it for a while when I'm driving it will stop blowing cold. Also if I stop and park and turn on the car again in a hot day, it will blow warm. Driving along sometime I can feel the air get colder as I drive but warmer at idle. When I say warm, I feel by touch that the air is slightly colder than it is outside so I feel like it is working but very minimal.

Sometimes when I start the car parked indoors and go on my drive, the car will blow cooooolllddd. To the point that the air coming out the vents fog but then slowly dissipates. I've even had frost shooting out the vents, but also this goes away after driving for a while.

AC compressor and clutch kick on without issue. There is no restriction in air flow. So I am thinking it isn't the compressor, relay, or evaporator icing up. But that's based on my uneducated forum research.

I was thinking it could be an overcharge but not sure. What PSI on the lowside is normal for the fit? Can anyone help me with some steps to diagnose? TIA!!

 

First off, R12 hasn't been used in cars since the early 90's. You need an EPA license (at least in USA) in order to buy and handle R12. If you meant R134a, then I would advise you to take it in and let a professional fix the system. If you did put R12 into the system you just cross-contaminated the refrigerant that was in the system. No honest shop will work on the system because there is no way to recover the refrigerant.

 

It is indeed R12A. I am in Canada and we can get R12A on the shelves. I read that R12 can be mixed with R134A and even says so on the can. But I don't want to turn this into a refrigerant debate. Any ideas what mechanical issues might be causing this?

Anyone know what is normal for low side pressure with the AC Compressor is on? Thanks!

 

R12 uses mineral oil, R134a uses pag oil. The two oils are not compatible. The oil has to be compatible with the refrigerant in order for the refrigerant to be able to carry the oil to lubricate the parts that need to be lubricated.

https://community.cartalk.com/t/mixi...-with-r12/3195

Since R134a is the prevailing refrigerant for car ac system, why didn't you just recharge with R134a? If R12 is available in Canada, I'm pretty sure R134a should also be available. Sorry but I never mix the two refrigerants in order to get an AC system to work so I'm not sure what low side pressure you should be looking at.

 

I think the other responders here do not understand R12A vs. R12. While I would have used R134A, you have already gone the R12A/ R134a mixed route. R12A will work with any oil, (Mineral, PAG, etc) Yours is probably PAG 100. It will also work mixed.

If you were completely charged with R12A (Duracool, HC12, Frosty cool) we usually set the low side at 20-22 PSI with the AC on full and the engine speed around 1500 rpm. If it was charged with R134 the low side pressure would be much higher. So with the mix you have you are going to have to try something above 22 PSI.

You do have a symptom of being SLIGHTLY undercharged. I would stick a thermometer in the center vent and check the air temp at 1500 rpm with the AC on full and running in recirculate. I would look for the minimum temp at 1500 RPM and then add enough R12A to bring the temp up about 4 degrees or the low side PSI up maybe 5. It should not take much. Then go try it again and make more changes as necessary.

While R12A will give you a little better cooling, if you do not know what you are doing, I would remove what is in there, vacuum the system, and reinstall the correct amount of R134 by weight. There is a sticker on the AC evaporator shroud under the hood stating exactly how much R134 it takes to fill the system from scratch.

You can get about 15% better cooling using R12A but you need to know what you are doing when you install it. The last time I was in Brandon, MB I picked up several cans of R12A (Duracool brand) at Walmart. You can buy it here but I only know of one company where I can walk in and get it. That place is 80 miles away. Everything else is online and delivered by USPS or UPS. I primarily use it in vehicles that had R-12. On rare occasion I will use it in R-134 vehicles.

 

The Original Poster in his first post stated he used R12, later he change it R12a. R12a is NOT a refrigerant that is permitted to be used in cars in the USA. It is illegal to replace R12 with R12a in cars in the USA. R12a is composed of Propane and Isobutane, both highly flammable gases. R12a is permitted to be used in refrigerators. The chance of a refrigerator being involved in a crash in which the gases can escape is slim to none. The chance of an automobile being involved in a crash in which the AC system can rupture and allow the Propane and Isobutane mix to escape is more probable. Most DIYer do not have the recovery equipment to recover refrigerant from an AC system. A reputable shop will not work on recovering the mix of R12a and R134a because it will contaminate their equipment.

Here's a Wiki info link on R12a.

https://en.wikipedia.org/wiki/HC-12a

 

Nothing has changed over the years. Same arguments from people who have no experience with the product. Lots of scare tactics like it can burn but no examples world wide of it ever happening.

I personally have seen a fire where R-134 burned. It was not much of a fire because there is only a small amount of refrigerant in a vehicle. BTW, anti-freeze, engine oil, ATF, and gasoline also burns. All are available in larger quantities than the refrigerant used.

R-12 to R-12a conversion is illegal in the USA for on road vehicles. It is used all the time for things like huge farm vehicles. I buy mine at a local farm supply store or inline. R-12 to R134 to R12a is legal in the US. So there is a path to get there for an R-12 vehicle. R-134 to R12a is also legal in the US. I had a major engine fire in my motorhome. Over $10,000 damage. About the only thing that did not burn was the AC system with less than 1 pound of R-12a. I was more worried about the 18 gallons of propane, and 50 gallons of gasoline on board. The fire was a gasoline fueled fire. I fought the fire and won with AR-AFFF.

The guy in this thread is in Canada and was going from R-134 to R12A. So none of the above applies. If he ever crosses the southern border with that vehicle, I'm sure the Refrigerant police will not catch him because he is not doing anything wrong.

I install R-12a in R-12 vehicles and R-134 in R-134 vehicles. I still have part of a 30 lb container and a few small cans of R-12 around. Nobody wants it installed due to the cost.

 

Since you are not in Canada but in the good old USA what you are doing is Illegal. Maybe you're one of those people that believe the law doesn't apply to you. My reply to the OP was that he should have used R134a. Canada may not have a law against the use of the R12a in cars and trucks, but it is illegal to use R12a in cars and trucks in the USA and there are many people on this forum that lives in the USA. They may read your comments that they can get better cooling if they use R12a, but aren't aware of the laws regarding the use of R12a in cars and trucks.

 

Thanks for this response! I am running closer to 30-35 PSI so I think I may be overcharged. Do these symptoms also reflect an ovecharged system also? I As you and other have mentioned, I think I will just need to evacuate, clean and recharge the system properly.

I felt compelled to comment though, laws are laws but some are more reasonable than others. I feel like running R12A is a far less crime than say owning a gun without proper documentation. Or smoking weed. An endless debate but I am happy to say I am happy running R12A refrigerant with confidence that it will have minimal impact on the health and safety of others.

Thanks again!

 

Here is the problem. From your description we do not know if the evaporator is freezing up or if it is over charged and tripping the over pressure limit on the high side. We also do not know what the mix is between the R12A and the R134A. The two refrigerants have a different water freezing point pressures. I believe, and this is a guess, that you have more R-134 in the system than R12a (Duracool). If this is true then your evap pressure at the freezing point should be on the higher side and near the R134 value. From memory R134 evap at freezing point is somewhere in the 40's PSI, while Duracool is somewhere in the 20s. So I believe you are freezing the evaporator. If this is true, then adding some additional refrigerant to the system will raise the pressure above the freezing point and stop ice accumulation on the evaporator.

We were talking legal and illegal. While it is NOT not illegal in the US and Canada to install Duracool (R12A) in an R-134 vehicle, it is illegal, and also poor practice, to mix refrigerants. I normally would say to evacuate the system and refill with R12a or R134A. In this case since you have already mixed it, I am willing to see what we can do to save what you have and get it going.

Good Luck