mdadmd

Tried the ac for the first time on my new '91. Very little cold air. Someone told me it was easy to recharge. Is recharging the ac a "do it yourself" job or should I take it to a mechanic? If so, how do I do it? Thanks.

Drew_K

Do you have R12 or R134a? Reason I ask is that R12 is very expensive and hard to find. If your car still has R12, you may want to consider converting to 134. Last time I checked, R12 was $75/lb and R134 was $3/lb.

mdadmd

Drew,

I have no idea on the difference or how to find out. Is there a way to find out what I have?

jimq

91 came with R12 from factory. The easiest way to tell is by the fill nipples on the compressor. I cant tell you what the difference is besides size. Only will fit either R12 or R134 tho.

LouZ

Take a look at the (2) caps on the side of the compressor. If they are colored - I think "BLUE" & "RED", then it has been converted to R134. If that's the case, it is a DIY project!

Johnny-Cat

And if it is still R12, you will have to take it to a place to have it recharged. I had my 91 for about a year now, and always had A/C issues. I just took it to a friend of mine that works at a service station who has the proper equipment. He did a evac, checked for leaks...found my two Schrader valves leaking, so we replaced them, tested again, then recharged. Yes the bill was close to $200.00, but I know it was done right with the right amount of refrigerant installed. I did some reading on my own regarding converting to the 134a. Since the car has LOTS of a/c lines, it is a bad idea to convert that car. Apparently the molecules of the 134a are actually smaller therefore causing more frequent recharges?? But I am thinking for the price difference in refrigerant, who cares if you have to top it off once in a while with r134a available everywhere!
Also in the 964’s, since the condenser coil is so small, the A/C is and will never be as cold as say a “normal car”. Mine was blowing about 45 degrees at the vents after the recharge. But for me and for that car, it is currently running correctly, and I am happy.

greenjt

If you convert, don't forget to install a new receiver/dryer (easy DIY, up under the left front fender) before you have a shop vacuum the r12, swap the valves, and install the 134 with the appropriate oil.

Steven C.

Also requires a different expansion valve and a sticker for the fan shroud anouncing the 134a in the system. The sticker is a 993 part#.

stevepaa

https://rennlist.com/forums/attachme...chmentid=95061


Factory does not change expansion valve between -92 and 93-.

Steven C.

You are correct, just what I thought was smart since I was replacing the drier and had the system open. Also emptied a bunch of oil out of the front condensor. Got 40 degrees out of the center vents at 80 degrees outside.

stevepaa

How much new oil did you add? I am about to do mine.

springer3

As long as you can get the gas and the tools, refrigerant recharge is easier than changing the oil (especially on a 964!). Production of R-12 was banned by the Montreal protocol after January 1, 1990. Porsche used old R-12 inventory through MY 1992.

Do a search - there was a debate about refrigerants a couple of years ago. There are several "drop-in" replacements for R-12 that are compatible with mineral oil. They are a good stop-gap if you need to buy another season before investing in repairs and change-over to R-134a. All "drop-ins" will have problems because they are mixtures, and the lighter chemical in the mix leaks out faster than the heavy one.

www.epa.gov has good technical information on R-12 replacements, including the chemical formulas, performance, and mix ratio if it is a mixture. It is one of the few internet technical resources on refrigerants that is not trying to sell a product.

The expansion valve does not need to be replaced unless it has failed. It is a flow-control valve that adjusts refrigerant flow based on temperature at the exit from the evaporator. R12 and R 134 both use the same valve. The air will blow at the same temperature regardless of R-12 or R-134a in the system. R-134a will consume a little more power for the same cooling capacity. IRRC, the difference is a couple of percent - not enough that you will notice. R-134a change-over requires flushing out the mineral oil and replacing it with ester-based oil. R-134a requires "barrier hoses". I don't know if all 964 models are included, but I understand Porsche used barrier hose and ester oil even on the R-12 964s. Ester-oil is compatible with both R-12 and R-134a.

I am still running R-12 and not leaking. Anyone still using it?

craig001

I am still R12. I usually juice the charge once a year or so. I have about 15#'s R12 left in my tank so I just slap on the manifold gauge and flow it in. I had the Porsche shop near Hershey do a system check and charge will at the 2005 Parade because my wife was complaining it didn't get cold enough. Ran me $180. Shop labor was about $40 less an hour there than here in Saint Louis.

Steven C.

Steve,

Sorry but I do not remember and I just pulled the reciept and the oil is not there? The part number for the sticker though is 964-573-943-00 My mechanic thought that flushing the oil out of the condensor probably made the biggest difference. I don't know but the system was not working well before and was after.

agentmacguyver

Hey everyone, new member here.

I have an '98 944 S2 and want to add some R12 equivalent to recharge the system, but can't seem to find the low pressure port. Does anyone know where it is located or a site that would have the technical info I need?

By the way, I'm planning on using Freeze12 which is supposedly environmentally safe, inexpensive ($60 on ebay for 3 cans and oil & pressure gauge), and cools better than R12, so WAY better than r134a. But it's all marketing to me until my AC is working again. If I can find the low pressure port, I'll let everyone know my results.