Kebal

Has anyone used the Freon in a can that Checker sells? Where's the fitting on my 993 C4S?

My AC works, its just not too cold

Thanks in advance!
Ken

amfp

First need to check your A/C pressure and determine if low on freon. My concern in just adding a can you may overfill, plus there may be a leak. Yes, I used it after checking pressure, but in my Volvo, not my 993. I later found best way is to first check if there are any leaks, and if no leaks, you should discharge all freon properly in recycle ontainer, and than fill to required pressure specs. So, with this, I had a A/C tech do for me, it was less than $100.

joon

Best to have all the proper guages when doing AC work. Measuring pressure of the system is critical for efficient AC cooling performace. Proper guages are not expensive, and since you're on the DIY path, the info is available on rennlist (I've read discussions before). If AC is not cooling, does not mean that freon is low. It can be other causes. I would not just attempt to recharge without knowing what pressure is in the system. Last year my AC was not cold, and I took it to the local porsche mechanic. For a 10 year old car, it was 1 pint low, so a minor recharge, and it was good to go.

Ray Calvo

Agree with joon (whoever he is) - and R134a refrigerant has been working great for 10 years, so I'm not mucking with anything different (if whatever Checker is pawning is different).

tj90

R134a prices have gone thru the roof the last year. Mixed products are now entering the market. Some AC shops have been known to use propane as a blend. This is dangerous as it can catch fire. There was a 928 that was toasted due to a leak recently I read about in popular mechanics. Whatever you use to recharge, make sure its 100% R134a (its ok to use the cans that have R134a and oil or UV....)

Kebal

Wow! Thanks for the feedback. It's 100 in Denver and with a black interior I need all the help I can get. I'll check the pressure and go from there. Thanks again!
Ken

dp2boy

Has anyone tried any of the freon additives that supposedly bring down the output temps. at the vents ?

tj90

Junk science....

dp2boy

I know it sounds shaky but according to one of my motorcycle mags the radiator additives (some) can actually lower the operating temps in a water-cooled engine so why couldn't the freon additives act as a catalyst to lower the evaporator temps a couple of degrees ? Any thermal engineers out there ?

mcuozzo

I wouldn't use any Freon that had additives or propane in them. This could severely limit your ability to have your ac serviced in the future. Any reputable AC shop should use a refrigerant ID machine before doing any work on your system. I would think that most AC shops wouldn't touch your ac system if it had a mix of refrigerants\other gases.

Since it became a federal offence to knowingly vent r12 or r134a to the atmosphere, all regfrigerant needs to be recycled\recovered. Most shops have a machine for each refrigerant, or a machine that does both and no one wants to risk contaminating an expensive piece of equipment, or render all their recycled refrigerant.

That's my .02 anyway.

Matt

deltawedge

The additional cooling effect that these coolant additives achieve is derived from the enhanced heat transfer from the hot metal surfaces to the circulating coolant (no surprise). The majority of heat is absorbed through localized boiling of the coolant flowing through the heads (vaporizing water at 212F and 1 atm requires 5 times as much heat as raising the temp of water from 32F to 212F). The Redline product Water Wetter addresses this heat transfer mode by reducing the surface tension of the water/antifreeze mixture such that smaller bubbles are formed (steam pockets are not good conductors of heat, so the smaller the bubbles the better). See their site for a full description.

Redline

Now onto the additives for AC systems. Unfortunately, the principle above can not be used for AC systems, because the refrigerant is not boiling due to heat being added to it (it is already a gas). Instead it is hot due to being compressed, and that heat needs to be removed. Reducing the boundary layer thickness of the R-134a going through the condensor and/or the evaporator would help the heat transfer. Reducing the thickness of the oil film in the evaporator and condensor coils would also help, since the oil is not contributing to the cooling capacity.

The AC booster that I found claims that it reduces the boundary layer thickness of the oil in the evaporator and condensor coils, which aids in heat transfer. It could be true.

Since the booster would be adding to the system, it would be best to evacuate the system and start with known quantities of oil and R134a and then add the booster, but similar results could be had by checking pressures before and after the addition, testing under similar conditions (ambient temp, rpm, steady state cycle times, etc) and monitoring the vent temps.

AC Booster

FlyYellow

it is worthwhile to note that an overcharged system (meaning too much freon) will be less effecient and therefore your cooling capacity would diminish. so really know how to measure the A/C pressure and get the gauge.