A/C recharge question
 

I need to get some R12 added to my system for the summer. The person who has done it in the past had Porsche experience, but has disappeared. I am wondering if I can just go to any auto a/c shop that has R12, or should I look for a place that has Porsche experience. Last time I called a local a/c place, picked from yellow pages, the guy tried to persuade me that he would have to convert the system to R134. I nearly fell for it.
I recall some postings a long time ago from an Atlanta Pelican who was also in the a/c business. I think he said there were some special techniques to recharging a 911, like making sure you keep the engine lid closed while recharging (damage to compressor otherwise?).

You need to keep the lid close so that air can be drawn thru the rear grille to cool the condensor.

Alternate is to use a fan to blow air thru the condensor, just be careful you don't scratch your car.

Some a/c shop use water to cool down the condensor, but with the condensor in a porsche you will have water leaking all over the engine.

The 134 retro fit kit for your car costs 25.00 bucks from NAPA

also the cost of 134 is about 1/4 of the cost of R-12.

You need to flush the system and replace the drier/receiver and change to barrier hoses if you decide to switch to R134a. If you factor in the cost to flush plus to replace the drier/receiver and new barrier hoses vs just topping off the system with R12 it may be cheaper and R12 is still a better refrigerant than R134a for the older porsche a/c system.

EPA licensed A/C service operations are not allowed to just top off with R-12; I believe they are required to check the system for leaks and repair same before adding R-12.

If the R-12 hoses are not leaking they do not need to be replaced when doing a conversion to R134a; the old oil stays in the hoses as it is not miscible in R134a and seals the R134a well against leakage through the hose wall. Only the condensers need to be flushed ($13.00 can of aerosol flush complete with dispensing hose and nozzle will do them both); the majority of the old oil is in the condensers, the compressor and the receiver drier which should be replaced. The compressor needs to be drained and refilled with new ester oil ($8.00 a bottle at AutoZone). The receiver drier needs to be replaced (available at AutoZone and NAPA for $20 to $30). Also conversions should include an over pressure shutdown switch for the compressor; switches that mount on the compressor discharge port are available. Then the charging fitting adapters are installed. Usually in the conversion kit, but I've found that some of the kits do not have the proper high pressure fitting adapter for 911's. Then vacuum pump down, check for leaks, then charge with R134a using a R134a refrigeration harness. Cheers, Jim

Another Urban Myth.

Most competent A/C Technician will check for leaks, but it is not an EPA requirement, but if they can't find a leak, they can still top off a system

See this link or read excerpt from EPA website

http://www.epa.gov/ozone/title6/609/recharge.html


My technician told me that EPA regulations prohibit topping-off the refrigerant in my car without getting the leak fixed first. Is this true?

EPA regulations do not dictate any particular service, as long as your technician is certified to work with refrigerant and any recycling equipment he uses meets EPA standards. EPA does not require that leak repair be performed before refrigerant is charged into a vehicle, although certain states and localities may require leak repair.

In addition, EPA does not require that the refrigerant be evacuated and cleaned prior to recharging the system with refrigerant. In other words, if your technician tells you that EPA requires evacuation and recharge and does not permit top-off, he is mistaken. If you are unsure about any EPA regulations governing auto air-conditioning, call the Hotline at 800-296-1996.

It depends upon which "Urban" one lives in! The EPA doesn't require leak checking prior to "topping off" but some states and localities require it; from the Bay Area Air Quality Management District:

Subpart B of 40 CFR 82 is amended to include the following additions standards.

12-7-301 Prohibition of Service

No person shall add refrigerant to any motor vehicle air conditioning system unless that system has no detectable leaks as determined by the following procedure:............

Didn't you state in your previous post that

EPA licensed A/C service operations are not allowed to just top off with R-12; I believe they are required to check the system for leaks and repair same before adding R-12.

Yep, I was wrong about the EPA. It appears the State of Colorado also requires leak checking prior to topping off so it just isn't the People's Republic of San Francisco Bay. I didn't check the Land of Lincoln regulations, have you? Cheers, Jim

I live in florida and we need a/c. My shop is using enviro tech since 3 years and it works great as a r12 replacement. the pressures are 25% lower and the efficienty is better. cost to refill is only $ 40.- or so.
Search internet for that.

thanks, harold