Refurbish 91’ Toyota AC system or patch it?

[Kurtatron]

Bitogres:

I have an old Toyota Previa which has a leaking AC system. I have not pinpointed the leak yet. I have had the van for 7 years now. It runs great and is immaculately cared for.

But AC is one creature comfort I simply require. This van is my summer camper van, so the AC is mandatory.

My question, how feasible is it for a DIYer to refurbish an AC system? I want to eliminate the leaks. Since it is so old, I am thinking replacing every possible seal I can, except for the rear passenger supplementary AC components. I am fairly handy, done major engine and transmission work. I have never tackled AC work due to the refrigerant environmental issue.

I am just wondering, what kind of fine-art dexterity and fancy tools are required to refurbish AC systems? As far as I am concerned, if I can get a reliable and leak free AC system, it will extend my van service life indefinitely. No AC means I toss it.

 

[Lubener]

To do it right, you will need a vaccum pump and gauges. If you don't have these, you cannot do it correctly yourself. Being a 91, you would likely have to convert it to R134A in addition to making the needed repairs. I don't believe a/c work would be worth it on a 91.

 

[mattd]

How do you know the leak isn’t in the place you don’t want to repair (rear components)?

 

[SeaJay]

If A/C is mandatory, I would consider giving the vehicle away to someone in need of a vehicle who would be happy to drive it with the windows rolled down.

 

[Kurtatron]

I used a sniffer, and it found no leaks in the rear passenger area. It’s somewhere under the dash.

 

[Kurtatron]

I am not asking if it is worth it or not, just asking how much expertise is required to service the AC.

for example, I have never attempted welding repairs because it is too daunting a skill to learn. But I have done several timing belts and a clutch replacement job, because those are just bolt and unbolt jobs. Is AC similar?

 

[slacktide_bitog]

If there is no R12 left in it, you can buy one of those conversion kits and just put the new adapters on and fill it with R134a and the provided oil

I actually did this with an older R12 car I had years ago.

 

[KrisZ]

A set of AC manifold gauges is a must, as is a vacuum pump. Don't use any refrigerant that has stop leak in it, only pure refrigerant should be used. Also, find out if your system is R134A or R12, given the age of the vehicle it's an important bit of info.

 

[Donald]

The condenser next to the radiator is another place leaks are likely due to corrosion. As others have said you need to convert to R134a. Use appropriate oil. Avoid any leak sealer.

 

[mk378]

If you have zero pressure you can inject small amounts of R134a as a leak detecting agent and sniff for it. Do not run the compressor. Working on a system that is static like that is just ordinary plumbing. After making repairs so you're fairly confident there is no leaking, have a shop evacuate and charge it.

Positively finding the leak before taking any refrigerant joints apart (to introduce new leaks) will simplify things greatly.

On any dual air system the lines to the back are a common leak.

 

[Kurtatron]

It has r134a in it. There was a service bulletin years ago from Toyota saying conversion was a simple change of 4 o rings at the drier and a pag oil changeover.

 

[Kurtatron]

If you have zero pressure you can inject small amounts of R134a as a leak detecting agent and sniff for it. Do not run the compressor. Working on a system that is static like that is just ordinary plumbing. After making repairs so you're fairly confident there is no leaking, have a shop evacuate and charge it.

Positively finding the leak before taking any refrigerant joints apart (to introduce new leaks) will simplify things greatly.

On any dual air system the lines to the back are a common leak.

This is the heart of my question. So does resealing the lines require so much finesse, that there is little hope of resealing them properly myself?

i already own a dual gauge manifold set.

 

[wildcatgoal]

I had a 1992 Honda Accord that had R12 in it and the AC was dying. It would have cost me too much to convert so I sold it. I liked that car...

 

[KrisZ]

This is the heart of my question. So does resealing the lines require so much finesse, that there is little hope of resealing them properly myself?

i already own a dual gauge manifold set.

It's not about "finesse" it's about getting to every o-ring connection and actually getting your hands on all the proper o-rings, sizes and made of the correct material, as these things are critical to making a proper seal.
And if you are not going to do the rear AC, then your job is not a refurbishment, just an exercise in futility. I would simply find the leak, fix it and not touch anything else.

 

[Kurtatron]

It's not about "finesse" it's about getting to every o-ring connection and actually getting your hands on all the proper o-rings, sizes and made of the correct material, as these things are critical to making a proper seal.
And if you are not going to do the rear AC, then your job is not a refurbishment, just an exercise in futility. I would simply find the leak, fix it and not touch anything else.

Ok, I suppose you may be right. I’ll probably take it to a shop and have them find the leak for me then.

 

[JC1]

With that previa you may have some of the aluminum lines cracked. On my 98 Sienna the rear line near the rear tire cracked and I replaced it with new lines from Toyota. Failed again 2 years later. Then I decided to use a block off, by getting a guy to weld the rear connecting fitting shut. Ac was never as good. Did the vacuuming and recharging myself.


I would check with your local Toyota dealer to see if you can get all of the AC components of they are needed. Then I would go from there. Good luck.

 

[nthach]

This is the heart of my question. So does resealing the lines require so much finesse, that there is little hope of resealing them properly myself?

i already own a dual gauge manifold set.

Toyota sells the O-rings for the block and pipe joints. It’s a doable job. Many of those joints use a 10mm bolt to hold them. the pipe flare joints use a 20-something mm wrench. The hard lines and hoses are NLA, so if one is cracked, a local guy will have to fix them. They are made out of aluminum. Any competent hydraulics shop can crimp and braze new AC hoses.

Now the heat exchangers and dryer, unless Denso still makes them you’ll have to deal with Chineseium there. It’s always a good practice to install a new dryer with a fresh fill of PAG/POE oil for R-134a unless you live close to the Mexican border and can venture into TJ/Nogales or south of the Rio Grande for R-12.

 

[Lubener]

I am not asking if it is worth it or not, just asking how much expertise is required to service the AC.

for example, I have never attempted welding repairs because it is too daunting a skill to learn. But I have done several timing belts and a clutch replacement job, because those are just bolt and unbolt jobs. Is AC similar?

Your question basically has been answered. A/C work requires special equipment. Timing belts and clutches require a pair of hands and some wrenches, those repairs are totally different from a/c work.

 

[Lubener]

Your question basically has been answered. A/C work requires special equipment. Timing belts and clutches require a pair of hands and some wrenches, those repairs are totally different from a/c work.

Woops.

 

[atikovi]

A/C work requires special equipment. Timing belts and clutches require a pair of hands and some wrenches, those repairs are totally different from a/c work.

A/C work won't destroy your engine if you don't tighten a bolt correctly.