Perry 951

I removed the sticker when I painted the engine bay, and I cannot remember how many ounces of R-12 were in the original system.

I'm gonna charge her up with 134a tonight and need to figure out the 80% of the R-12 charge.

Also... although the system is clean and new.. I have not had a chance to get a vacuum pulled on it yet. Am I asking for trouble? I have about 16 hours of driving to do beginning Monday, and I gotta have some AC for this trip, since temps are supposed to get back to normal in the Midwest.

TIA!!

AndyK

Does the number 33.4 make sense? I seem to remember seeing that on the yellow sticker. can't check since car is at home...

Perry 951

34 oz rings a bell.... but I wanted to be sure.

Jeremy Himsel

Perry,

33.5 is the right r-12 amount. If you have the drier installed without pulling a vacuum there's a chance of allowing moisture into the system but it's not likely that will affect your system's performance very much unless it's extremely humid where you live. What I would do is pull a 20 minute vacuum, charge the system with about 6oz of 134, and then pull another deep vacuum. The freon introduced into the system will help get rid of any moisture that is in the system.

Perry 951

I am going to do a system flush before the charge to help get any moisture out of it. The problem is that the service shops around here won't just pull a vacuum on it for me without doing the freon charge, and the ones that will do the vacuum are booked until next Friday.

I'm gonna do it right when I get back, but was wondering if I am gonna cause issues doing the charge without pulling a vac on it. The system will be charged for a week, and used on the trip out and back. (16 hours)

This is what I get for my procrastination... :P

nine-44

Brian, I have a vaccume pump, you can use it here along with our guage set too. It's dad's tools, he doesn't let stuff leave. If you can make it, call me, I'll be under mom's car and probably not able to check this post.

Randy_J

Perry - did you keep the OEM system or install a retrofit? Keep us posted on the progress - have to do my son's 944 NA aircon sometime soon.

Thanks

951Tom

Perry, go to FR Wilk's link below. He's got a copy of the PCNA tech bulletin for upgrading cars. You need 860g of R134a.

http://frwilk.com/early944/ac/page05.jpg

nine-44

I'd vaccume it, you don't want the moisture in there if you have an option not to. It's hard on the compresor, moisture repels the already thin oil in the system. Your call tho!

Perry 951

Andy - I'm there! Probably about 7:30 or after... today is the long day. You have a compressor so I can blow out the flush, right?

Oh.. I'll grab the big wrenches for ya too.

Perry 951

FYI.. 860 Grams is 30.33 ounces.

Perry 951

Andy K - I read your other post and was getting ready to respond. The OEM compressors will work fine with R134a. You'll want to get all the oil out of the old compressor and fill with retrofit R134a oil, since there will be residues of the R12 oil in it. The retrofit oil is supposed to be compatible. My retrofit is using my stock, cleaned out compressor..

New Drier and O rings are a must, and it's not a bad idea to change the expansion valve. After that, a good flush is needed, and also pulling a vacuum (where I am at) to make sure moisture is out of the system.

EDIT -where did his post go????

nine-44

Cool man, I'll be here. You may want to bring a section of hose for the compresor. I don't know if the hoe we have i long enough to reach, I've got two 944s in the air and can't get all the way back to the garage right now. Seeya then!

nh3

Pulling a vac on the system is not done to remove moisture, that more of a side affect. Pulling a vac is done to remove air from the system. When you have air in the system, the air will hang up in the condenser reducing it's condensing capacity. This in turn will give you a higher than normal discharge pressure which will raise your suction pressure because you are now introducing hotter than normal liquid back to the reciever then fed via the Tx valve to the evap. This will now cause your evap pressure and temp to go up resulting in not so cold vent temps. Keep in mind pressure and temp go hand in hand. Higher pressure = higher temp. The lower the pressure, the lower your temps. Also with the higher discharge pressure due to air in the system your compresser should cut out on high discharge pressure via the high pressure switch reducing what little cooling you had while air is present in the system. I have never tried it but I have a friend who made a vacuum pump by hooking up a air compessers intake, and letting it dischare to atmosphere rather than the air compressers tank, to the refrig system to pull a vac. Also if a large amount of moisture is left in the system it could form ice inside the Tx valve and starve the evap of liquid.

nh3

triscadek

I recharged a Toyota p/u without doing an evac. and another problem is very little cooling at idle.