Hey fellas,

I need some help from the A/C gurus here. I know many threads have been floating around on the subject, and I have searched and read a good few of them, but I still have some unanswered questions. Hopefully someone can chime in and help out an ignorant soul.

My '91 XJ has A/C... but I have never used it. IIRC (God it's been so long since I bought it... and my memory is already escaping me), the owner mentioned something about the A/C. I cannot remember. Anyways, I have never really tried running it on just A/C out of fear of something exploding or God knows what. HOWEVER, I have used the defrost many a time since I have bought it, and it does it's job well. I believe the A/C compressor does cycle for the defrost right? I have also noticed if I switch from one side of the HVAC controls to the other and pass through the A/C section, the compressor will seem to kick on for the split second and back off as the switch passes over. Good sign?

Anyways, I want an A/C overhaul. I imagine a 22 year old system could use some TLC. So where do I begin? I believe I must switch to R134a. But I remember one thread mentioning it has a higher risk of escaping through old R12 lines? Does this mean I should replace the lines as well? Also, how would I go about checking for any existing leaks? Taking it to a shop? I also understand it is good to replace the drier? Also, can the condenser and evap core be flushed?

Like I said, I am a total noob to the A/C system. All I know is I would really like it to be working and up to date. From the looks of it, I can replace the hardware like the drier. But any and all evacuation and recharge I'd let a shop do. Again, all input is appreciated!

Also.. on another note. My little cold/hot lever never fully goes the full left cold part. It always stays about 1/2" from the end. I can force it over, but it's like something is holding it back. Any ideas?

Thanks again!

 

Well...
based on you description, I'm not sure I'd tackle an AC conversion unless there is an actual need to.

You say that the defrost works well, and you can hear teh compressor kicking on when you "pass through" the AC settings you can hear it kick on. yes, these are both good signs. If you put the AC on full blast, let it run for awhile. If teh compressor stays running for several minutes, you most likely have good freon pressure in the system. If it cycles on and off every 5 to 30 seconds, you probably have low freon. However, even if it's low that doesn't mean you have any major issues. Twenty one years is plenty of opportunity for things to get a little low. R12 is ungodly expensive. I've seen prices quoted of $120 a pound. But if your system just needs to be topped up with a quarter to half pound, that's still gonna be cheaper and likely a better solution that trying to do a conversion. Even at a full 1.25 pound charge, you still may be better off.

If a conversion is in order, it can be a DIY scenario. There are some retrofit fittings that get attached to your existing ones, some special lubricant/additives that bridges the gap between R12 and it's normally associated oils and R134a and its oils so that you have some stable chemistry that will play nice together. These things are sometimes sold as complete kits. I haven't bought one since I converted my old 91 RX-7 about 10 years ago, but I think it was about $75 at that time. No idea now.

All that being said, here are some caveats to doing a conversion with all or most of your existing hardware, namely the compressor, evap coils, and condenser coils. It is common for converted systems to not perform as well after the conversion. The reason being that the two different types of freon have different compression and expansion characteristics, and the evap and condensor coils, along with any other plumbing, may not have the ideal internal volume needed for r134a. Also, there can be pressure issues that your R12 compressor may not be able to deal with in an ideal manner Will it cool? Yes. The question is how well. I'm not saying you'll necessarily have issues, but it is something to consider and have a talk with a competent, qualified AC technician about. My guess is that the DIY kits probably don't give as good of results as having a shop do the conversion and doing a proper vacuum and fill. Again, my choice would be that if you have a sound R12 system that may just be a tad low, try to keep it an R12 system and only do the conversion if you have a major failure, like the compressor. My uncle has a Kelvinator fridge from the 50's in his garage that still keeps Cokes ice cold! No conversions for it!

On your hot/cold control issue, you probably have a plenum door/flap that is failing at the pivot, or it has something that may have gotten in there and is binding it up. You could try getting access to the cable the controls it and spraying some silicone or PTFE lubricant inside the cable sleeve and work it back and forth a bot and see if that helps.

 

If the system started out as R12, keep it that way.

Your temp control lever position and travel is normal.

 

Awesome! Thanks for the info! I'll start her up today and turn the a/c on.. see what happens. If this whole time the a/c DID work and was maybe just a little low.... I might have to kick myself in the **** lol.

So the control is normal? I'd think it would travel all the way to the left like it does the right? But I won't argue... like I said, HVAC is beyond my scope of knowledge. I just sit and hope it works lol.

 

An old system still operating is not unheard of. Several years ago, I bought a '76 Ford for restoration which had factory a/c. It still worked and was an original system which appeared to never had been modernized in any way.

The only drawback to keeping it an R-12 system is that you will have to go to a professional to have it recharged. You can't get R-12 cans here any more unless you find some still around at a swap meet, and then you'll be paying premium $$ for them.

Macgyver gave you very good and complete info. The 134A conversions are very simple to do if you end up wanting to go that way. We (AZ) and the others still sell conversion kits which are relatively inexpensive. It's not rocket science if you end up trying to do a simple conversion without replacing the components that Mac mentioned for a complete change-up. One caution. Be careful venting the R-12 out of the system. By law, you are supposed to go a pro to have the old freon vacuumed out and not released into the air. Most DIYers don't. DO NOT BREATHE ANY OF THIS STUFF IN IF YOU VENT IT OUT YOURSELF!! It will hurt your lungs very badly.

Any other questions, we're here.

 

Trust me, I abide by the laws when it comes to the automotive world. And plus, I'll be the the first to admit I have never handled freon or anything like that. Any vacuum drawing or recharging would be done at a certified shop, and the freon disposed of properly. Last thing I need is a frozen lung OR a ticket lol.

 

1. Diagnose.
2. Replace parts if necessary

OR!!!!!!
Keep replacing parts if you have too much money and time.
AC system is not complicated.
Conversion to 134 kit is about $7-10

 

PLUS: Filter/dryer, expansion valve, change compressor oil, flush system, barrier hoses, O-rings, etc.

Even then it will run at least 8 degrees warmer than the R-12 would have.

 

I did last conversion long time ago. I just added oil and installed valve adapters. That is it.
Everything worked fine, no problems.