A/C in the 91

[watchdog]

The A/C in the 91 LTD is DOA. the compressor is locked up. I know I need a new compressor. I wanted to take this opertunty to convert to 134. Will I be able to just flush the system and charge with 134 or is there more to be done? I have never converted an R 12 car before.

[King_V]

I've done it with just using the R134a... well, ok, Autozone had this conversion kit that was some R134a with a chemical in it that claimed to make the old oil compatible with R134a. Oh, and of course the fittings for the high and low pressure ports.

Since the car I tried it on had lost all its freon anyway, I gave it a shot.

It seemed to work pretty well - in fact, strange as it was (this was a beat up 1985 Accord I got for free), the thing got colder way faster with the R134a than it did with the old R12. I was surprised at this since I'd read that Honda compressors were marginal, and usually didn't respond well to the R134a conversion.

Now, I'm given to understand that the proper way is to drain the old oil, and use only the new oil in the system. Also, I think something called an orifice tube needs to be changed, the O-rings should be changed to the type that'll hold up to R134a, and the hoses SHOULD be changed, but since the old ones probably have glazed on the inside, leakage shouldn't be an issue (I think it's something to the effect that R134a will actually seep through the old type hoses and O-rings under normal conditions, if those hoses and O-rings were new rather than glazed from age).

I'm a little spotty on this, though, as it's been a while, and I never really studied it too closely, given the car I'd done the quick-and-cheap conversion on was a beater.

[gadget73]

If you're opening the system, replace the drier. This should be done any time the ac system is opened. I'd also replace the orifice tube too, they're like 20 bucks and live just inside the evaporator. Undo the liquid line (the small one on the bottom of the evap) and its right inside there. Replace the O rings at the various connections with the green nitrile ones, and flush the system out just to be sure the compressor didn't grenade and leave any crap behind. Oil the system up with ester oil, I think its 8 ounces you need, but it might be less if the compressor comes pre-charged with oil. If it comes with mineral oil, dump it out. It won't hurt anything but the R134 doesn't move it so its useless to you. Vacuum the the system down to boil off any moisture, then charge it.

[PICKUP6772]

I converted my 89 GM 3 yrs ago. I had no A/C when I got the car. I vacuumed the system out, changed the O-rings, re-vacuumed the system, and the recharged with ester oil, and R134a. Amazingly, the system cooled the car almost immediately. I did have an issue last year, when out of the blue, one of the A/C hoses EXPLODED!! When I say exploded, I mean the people at the bus stop I was passing ducked for cover, and left an unpleasant stain in my pants!! It was the hose that runs from the drier the A/C compressor. I changed it out, vacuumed the system down, and recharged it. Have not had an issue since. Btw, when the system is up to par, I can hang meat in the car. In fact I ran the A/C last week when we got into the low 70's on friday, and all was well.
MIKE

[86VickyLX]

The A/C in the 91 LTD is DOA. the compressor is locked up. I know I need a new compressor. I wanted to take this opertunty to convert to 134. Will I be able to just flush the system and charge with 134 or is there more to be done? I have never converted an R 12 car before.

Like probably already mentioned, you will need to replace the reciever/drier, and replace the black o rings with the green o rings. While you're in the system you might as well change the orifice tube which is located in the bottom pipe of the evaporator. You may need a special tool to remove the tube. Now to open the system in a '91 you will need the quick disconnect kit. You can find them at any parts store. They are basically plastic rings that are open at one end so you can slide it over the hose, and disconnect the fittings. Naturally, before you do this, make sure all of the old refridgerent is out, unless you want to flash freeze a part of your body. Buy yourself a retrofit kit, it consists of the high and low ports, blue for low and red for high. The kit should also come with a sticker stating that the system has been converted to 134A, and an 8 oz bottle of ester oil. It MUST BE ester oil. Anyway the high screws right on that line coming from the compressor, and unless noted otherwise, you will have to remove the valve stem from inside your new receiver to put the new retrofit low port in place of it. Also, if the compressor has seized, I would definetely flush the system. If you have an air compressor, that's good because you will have to blow out the flush after you've sprayed it. Read the instructions on the can. When everything is ok, and dry. Put 2 oz of ester oil in the condensor, 2 in the evaporator, and 4 in the new compressor. When the system is sealed, you can vacuum it, if you have a vacuum pump and remove all of the moisture from the system. When all of the moisture has been removed from the system, you may charge it with the 134A. Cans must be upright. Your system should take '3' 12 oz cans of refridgerent. Turn on the car and set the air controls on max air, with fan at full blast. The new compressor should start to cycle. You can check the progress of the bottle by feeling it. Where it is warm there is no 134, where it is cold, that's how much you have left. The more time that goes by, the longer the compressor will run until the compressor doesn't cycle anymore, which means you're done, and you should have cold air coming out of the vents. Good luck!

[Lincolnmania]

like the others posted, i have taught them well lol
replace the compressor, the drier, the orfice tube, flush the lines, replace the o rings, install new fittings and oil and charge

[ss_mini14]

Cans must be upright.

not really, unless you like to spend your time watching pots of water boil. i've never had a problem charging with liquid. the only time i saw any damage was when some a-hole wandered off to smoke while it charged and grenaded a york compressor on a freightliner. i recovered almost 7 lbs of 134a from a 3 1/2 lb system.

[351m]

I have used R12 compatible retrofit kits on systems that were still charged but not enough for the compressor to run. They seem to work great. I think it was Duracool from Wal-Mart but I could be wrong on that as I have tried a couple different ones.

[Lincolnmania]

it is best to get the r12 and what mineral oil you can out of the system for best performance

[gabegt90]

I think the stock spec for the amount of r12 you put in is 3 lbs
since you are going to do r134a it will be less around 2lbs.13oz that's what mine takes

[Pirate]

One of these days, I'm going to get around to using some of the HC-12 I have sitting here....

[gadget73]

I have used R12 compatible retrofit kits on systems that were still charged but not enough for the compressor to run. They seem to work great. I think it was Duracool from Wal-Mart but I could be wrong on that as I have tried a couple different ones.

Never do this. It can make things fail in an ugly way. It even says on the cans to not mix refrigerants.

[86VickyLX]

not really, unless you like to spend your time watching pots of water boil.

It really didn't take that long.

[Lincolnmania]

80% of the r12 charge is what you want to use in r134a

[351m]

Never do this. It can make things fail in an ugly way. It even says on the cans to not mix refrigerants.

The reason I bought it was because it was compatible with R12 and I didn't feel like getting it evacuated. That is too much money to spend on a free minivan that had only partially discharged due to lack of use. I do see the point with the different oils and all though

[watchdog]

Thanks for all the info. Just for the record, there is nothing in the system rright now. No pressure at all. That's why I was going to do the convertion now instead of just recharging.

[watchdog]

Next question.

Is the AC compressor for the 351/5.8 the same as the 302/5.0 or are they differant?

[trwp72]

They are the same, maybe different mounting, but the should be the same. We can compare to my car.
Just looked in two different auto parts look up... both are the same on both websites...
(Adavance and Auto Zone!!)

Tom...

[gadget73]

Same compressor, just a different bracket.