Sorry this not a Camaro question and moderator you can move it to a better thread if needed.

The A/C on my daughter's 93 Corolla is shot. I had it checked out and he said it is plugged up somewhere and he suggested I replace the condenser and dryer and stay with R12. Total estimate was $800. More than the whole car is worth.

I am thinking about doing the work myself and converting to r134a at the same time, especially if I can find a good condenser in the bone yard. How much work is it to replace the condenser and dryer? What is the process to convert to R134? The kit dosn't look like much, just some fittings, O rings and can of oil?

I am not experienced the Corolla, but I am knowledgeable on a/c. A little more info would help. When you say shot, what does that mean? Is it still holding a charge? I sympathize with your financial dilemma but guessing at a fix can be just as expensive. Are you sure of the diagnosis? Condensers generally don’t plug up internally. Externally, yes. If he thinks that it is plugged somewhere and you still have refrigerant in the system, the restriction will show up as a “warm to cool” spot in the system. Every part in the system except the evaporator and the line running from the evaporator to the compressor should be hot or warm when the system is running. A condenser failure is a matter of seeing high high-side gauge reading. Do you have access to gauges to see if what they are?
As far as changing to R134A, the kits are universal and as such, will work for most applications. They are only intended to give you new refrigerant, oil compatible with R134A and R134a fittings that are required by the EPA. The dryer or accumulator is the only part that must be replaced during any conversion. Older desiccant is not compatible with R134a.
Also, never use an old dryer, new only because of the desiccant
Gary

The original problem was that it started off rather cold but got warm in about 10-15 minutes, then never got cold until it was turned off for a while. When I took it to the shop he said it had .3 lbs of R12 in it so he put 1.5 lbs in it to bring it To capacity. Then he said it still did the same thing and he only had 125 lbs of pressure on the high pressure side coming out of the condenser I think. That's why he thought it was a plugged condenser.
As for holding a charge he said it was holding the R12 with no leak down.

As reddoter suggests, a plugged condensor would generate a high high-side pressure.

A reading of 125 PSI may suggest non-compressable gas mixed in with the freon.

I'd get a second opinion. Suction line from evap to compressor, the larger hose, should be sweating at its metal parts with engine rpm around 1500 rpm and a box fan in front of the car directing air through the grille.

The touch temp of the hose should be close to interior vent tempaerature.

I did stay at a Holiday Inn Express.......................LOL.

Let me ask this a different way. What is involved to convert R12 to R134a?

Suck out all the R12
Replace to receiver/dryer
repalce fittings and O rings?
Put in new R134a?

I have a 88 F150 that I replaced the compressor on years ago with one from the junk yard ago just to get a good clutch pulley on the serpentine system. The guy at the junk yard thought the compressor was still good. Is it worth trying to do this conversion? Mostly I just want to learn how to do it.

On the pickup, you will need to empty out the oil that is in the compressor. you will need to replace the oil that is taken out, probably about 4-6 oz. The potential problem with the used compressor is how contaminated is it on the inside. If it has been capped or it is relatively clean on the inside and the compressor turns freely, it’s probably worth a try. I would suggest you do the repairs and take it somewhere to get charged. There really is no substitute for tools: vacuum pump, gauges etc. As Everett said non-compressible gas is air. If you get air in the system(and it's there now), it will not work.
Gary

How much vacuum do you have to put on the system to empty it out? Can it be done with a hand pump (Mighty Vac)?

A vacuum pump actually does 2 things: 1st is to remove air. The hand pump will work for that. The second thing it does is removes moisture. That requires a pump that will pull something in excess of 29 inches of vacuum. The hand pump won’t do that. The down side will be a shorter life on the components. It is probably not significant enough to worry about. Make sure you put a new dryer on though.

Tool rental shops can rent these tools. But, you should have freon, oil, and new dryer on hand before doing the job. You could use a Mity-Vac hand pump, but your forearms would be the size of Atlas's biceps........

The longer the vacuum cycle from the pump, the more moisture removed from the system. Another thing I like to do to a new/parts changed/closed system is pressurized it with 200 PSI of nitrogen and check the whole system for leaks just before adding freon. No sense in wasting freon if the system is leaky.

If you have a good set of gauges and connections, you can leave the charge overnight, one day, or as long as you want to check to make sure the system doesn't have any leaks. You must account for temperature changes, system test pressure will change.

Used condenser from an operating system is OK, Not hard to replace either.
NEW DRIER.
Now buy the Retrofit kit, add the ester oil to the proper amount and NO EXTRA.
remove old schrader valves, add new R134 fittings.
evac
and charge to 80% of R12's old charfe weight.

Doesn't sound too bad. I didn't think the condenser would be too hard but I haven't looked on that car yet so I don't know what all will have to be pulled off to get the condenser out. Is there a way to test the condenser first to see if it's blocked? Sounds like from other's responses to this question they didn't think they went bad very often. Any idea how hard a drier is to replace?
How do I know how much ester oil to put in it? I have a friend who has gauges and r134a so he can hep with the recharge. I may tackle this just to see how it's done.

Oh, I noticed you list evac after putting the ester oil in. Don't I need to put a strong evac on it to pull out the old oil before putting the ester in and wouldn't evac after that pull the ester out?

In your earlier post you describe the system as working then not after about 15 minutes. If true it sounds like a moisture problem. Moisture can be in the system freezing the txv or orifice tube or the thermostatic switch has failed, causing the evap to freeze up. That is an easy fix.
Since you have access to gauges, put them on the system and see what it is reading. As far as testing a condenser is concerned, look to make sure it is clean on the outside, free from debris and the fins are straight. Check the lines going in and out of the condenser to make sure there are no kinks. If the system is still charged, run it and put a thermometer in the fins at the very top of the condenser and the very bottom. You will be able to note a temperature drop, perhaps as much as 20 degrees. If you can get gauge readings, a failed condenser shows up as high head pressure. The dryer is easy an easy replacement.
Gary

Where I'm at at the moment on the Corolla is that the last shop that diagnosed it as blocked condenser pulled all the R12 back out of it so they wouldn't have to charge me for that so it's sitting empty right now.
It's funny my friend who does commercial HVAC said it sounded like moisture in the system but he didn't have a chance to look at it before I took it to that shop. I described to them what my friend thought and they said they didn't think would be it?
It sounds like maybe I should replace that thermostatic switch and drier and do the rerofit and see what I get with r134a. Where is that switch located? I'll read up on replacing it.

Looking at Adance Autoparts online they show a thermostatic switch uner 93 Corolla A/C parts but it's greyed out like it's not available. They do show a Trinary switch. That's not it is it?

Unfortunately I am not familiar enough with the Corolla to tell you where the switch is located. I did a quick internet check but didn’t find anything. Check the part at a local auto parts store. If moisture was your problem, replacing the dryer, thermostatic switch and recharging will fix the a/c in both scenarios.

When you pull a vacuum your not pulling oil. That needs to be flushed. Since the system is emptied, can you get to the lines going to and from the condenser? If they are similar to our Camaros (close to one another and right at the condenser), disconnect the lines and pressurize one end, the air should come out the other side freely if not plugged.



Try this. Go to http://www.autoacforum.com/ The folks running that web site are auto a/c mechanics. Not a shade tree Auto A/C mechanic such as myself. Give them the same info you gave us here. They love a challenge.

They also run A/C kits.com there you can buy the retrofit equipment very reasonably if you want to switch to R-134.

The Evacuation removes the air and moisture.
The amount of oil should be listed on the sticker next with the freon charge.
26 oz of R12 = 21 oz of R134
the oil,, about 6 oz should be close.

Sounds like you got the Toyota covered on a First Gen Camaro site! Awesome.

I may add it you have an alumin condernser and you suspect you have blockage which occurs as water and alumin don't mix well,,, you prolly do have a blocked conderser, you can tell it as its gonna build lots of heat. Well , If you had access to the nitrogen , you could try to blow thru the condenser, if you don't get much return,,, you got it. Finish the rest like all these guys said.

One safety item I forgot to mention, you should let your A/C buddy connect & disconnect the gauges.

If you don't connect & disconnect in a rapid matter and wear leather gloves, you can burn your skin by being frozen with the freon. And don't breathe the stuff either. Keep away from eyes especially.

Forgot to mention, this is the perfect time to convert. R-12 is hard to get even with a license. R134 you can get at wallyworld.