Refrigerant Question

bryceshagen

Registered User
I have done some tests regarding my non-functioning A/C in my 1991 SC and found out that it is low on refrigerant. I am a little sketchy on what to use, how much to use, and everything else concerning the A/C compressor. Thank you for all of your time.

Bryce
 
If it's never been touched and is still running R12 you'll need to convert it to R134A. The kits are at all of the auto parts stores for $35 Just follow the directions and it's not difficult to install. They come with enough refrigerant to fill the system and you can get extra 12 oz cans for $6-$7. They also have little gauges for $10 to check the low side (blue fitting) pressure. You can check your compressor by turning the clutch and feeling if it turns smoothly for several revolutions. If it has a tight spot every so often as you turn it the compressor is probably bad, otherwise it's probably Ok. I just went through this with my 35th and one of our local chapter members is a Ford factory A/C mech and did it for me.
 
Ixnay on the onversion-Kay.. If you have a good compressor, IMO, find/fix the leak, replace the accumulator, pull a vaccuum, and recharge with R12.. even though its more expensive, it'll be cheaper in the long run and work better (colder).. the key thing is though, your system has to be in good condition and the only problem truely is a leak through one of the Orings.
If your compressor is locked up, or the leak is in a key component such as the compressor, evaporator, or condenser, think about converting to r134a; its going to be a bit pricey to start with to do it right.

You can take a short cut and buy the Interdynamics kit, and cross your fingers, but the kit short cuts the work which ensures you system will live longer. (e.g. no flush, no vaccuum, no accumulator), just load and go. :cool:

I replaced my A/C a couple of summers ago and retro'd with r134a; its OK, but even with the new serpentine condenser, IMO, it still doesn't work quite as well as the original R12.
 
I called an A/C shop today and the cost of R12 is about $4.50/oz. For the 32 ozs that the system holds that's $144 just for the freon. Yesterday cruising at 40mph with an outside temp of close to 90 and my window halfway down, the thermometer stuck in my center vent read from 46 to 51`. I've been wondering how well that smaller condenser coil works.
 
Mike Puckett said:
I called an A/C shop today and the cost of R12 is about $4.50/oz. For the 32 ozs that the system holds that's $144 just for the freon. Yesterday cruising at 40mph with an outside temp of close to 90 and my window halfway down, the thermometer stuck in my center vent read from 46 to 51`. I've been wondering how well that smaller condenser coil works.
Well you certainly did the right test. That would be mediocre to not great performance. Most shops would say it doesn't quite meet specs since its about 40 degrees below the outside temp, but if they don't care about your business, they'll say its fine :rolleyes: They generally state that 50 is the standard. You wouldn't be real happy if it were 100 out, although Max A/C (recirculate) would get it colder.

Mine is hitting 44 from 95 outside on norm and 40 on recirc and that's with r134, a 6mm serpentine condenser, and a few oz of refrigerant missing due to a slight blunder on my part when taking some pressure readings. :eek: :eek: I intend to tune it later as I think 39 is achievable.

Also, the 90 holds 40oz of r12 and the rule of thumb is 80% of that for r134 which is 32oz. So for $180, it might be worth the conversion, but factor in another $150, or more, for an upgraded condenser to get better than mediocre cooling and you can see that retrofits aren't necessarily any cheaper. The condenser really is optional but much less optional if the compressor blew.
Usually, you want as big of a condenser as you can get and a tight set of small diameter coils which run in 2 or more parallel paths. The original r12 condenser is a tube and fin with bigger coils and 1 split path. It works great with freon.

I'd be curious as to what a shop charges for new orings, new accumulator, flush, vaccuum, fill, and the cost of the refrigerant which is what a reasonable job would include.

Anyways, most of the decision is up to the owner. There are low cost quicker ways that have a track record of killing A/Cs (the pros call them compressor death kits) and there are higher cost ways which aid the longevity of the compressor. Now factor in that a pro probably would discourage the kit cuz that's their business, but there are a few that say that the only way they'll warranty their work is if its done a certain way and none of them expressed any desire to do rework.

Due to a number of factors, mostly wanting to preserve my compressor warranty, and the cost and time of the job, I chose to do the full up job. In my case, my old compressor had siezed up. :cool:
 
With windows up and on max cool the thermometer will go to 37` cycle off and warm to about 46` and cycle back back on. It'll freeze my butt! I lose about 10` with the window down. That's with a new liquid line, too. The shop I called, just a random one out of the yellow pages, actually encouraged the conversion to R134A.
 
Mike Puckett said:
With windows up and on max cool the thermometer will go to 37` cycle off and warm to about 46` and cycle back back on. It'll freeze my butt! I lose about 10` with the window down. That's with a new liquid line, too. The shop I called, just a random one out of the yellow pages, actually encouraged the conversion to R134A.
Sounds like you may be getting a bit of evaporator freeze up. 37 is a bit cold as the evap core is probably below freezing. You can adjust this somewhat by pulling the pressure switch off and turning the screw about 1/4 turn CW and then see if how it affects the swing. Sounds like they, or you, hit the sweet spot though if its getting that cold on a hot day. Too much or too little refrigerant and it doesn't cool as well. It has to be juuuuuust right.
 
i tried the interdyamics retrofit kit yesterday. my situation is a little different. when i did my motor mounts i removed my compressor. i took the lines off the back not knowing much about A/C system and the R12 escaped by accident. i know i know, i'm now a wanted criminal but i'm pleading the 5th. i figured since the system was discharged, that i could just use the retro kit to recharge with R134. I followed the directions to a tee and after i charged it my compressor started kicking on and off every 5 seconds. now it's blowing hot air. i'm thinking that the R12 wasn't completely out? I got the R134 with the gauge on the hose and it says the pressure is good. I'm just gonna bring it to a shop and get bent over I guess. :mad:
 
Any time you open the system to the atmosphere you need to vacuum pump it to remove the air and inherent moisture. This moisture can freeze inside the lines and block them not to mention mixing air with the freon. So, you'll need to dump the system, pump it down, and recharge it with fresh R134A and oil. You'll need someone with the equipment or take it to an A/C shop to have it done. More than likely no real harm done. Dump the system 1st so they don't charge extra for that.
 
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