Interest in A/C writeup?

[Peterjojo]

Yes. I’m just about to put an AC unit in my 87 that never had it and want all the info I can get. Thanks. 

[WesD]

I've done this swap in a Chevy K10 before (it was pretty easy) - I'm hoping that GM and AMC/Jeep used similar design methodology where every system was a separate sub-system, which makes it easy to piece in the subsystems ad-hoc.   (Cruise, A/C, power windows, locks, etc would all be considered sub-systems).

 

I also recall seeing these complete systems for sale in JC Whitney for around $999.   Sure wish I had the kit today.

[Minuit]

On 6/11/2019 at 1:00 PM, DesertRat1991 said:

 

Great info!  I'm really looking forward to your chapters covering "parts selection for dummies."

 

I'm trying to piece together an R134A setup for my 91 and have already sourced the HVAC box and dashboard control panel from a '95 XJ.  I'd like to replace the heater core and evaporator.  Do you have any thoughts on copper vs aluminum for these parts?  My understanding is that copper transfers heat better, but the copper units aren't made entirely of copper.  On the other hand, the aluminum units are all aluminum so they end up working better.  

 

Also, does this UAC 4366A parts kit look like a good kit to continue building around?  I like that it includes a parallel flow condenser: 

https://www.rockauto.com/en/moreinfo.php?pk=9826464&jsn=365

 

If I can nail these items down I think that just leaves 4 hoses and a pressure switch left to find.  The '91 looks to be pre-wired for the compressor and pressure switch.  Am I missing anything?

 

Thanks.

A few thoughts.

 

You have a choice here. Not a big one, but it is a choice.

 

You can buy the A/C parts for your '91. That kit would get most of what you need, but I have my doubts that the condenser is right. This should present no problems with the '95 parts you already have. Or, you can do what a few of us have done @schardein and convert fully to the '96 R-134a native system. I have been extremely happy with my build, and I had no problems finding parts. The '96 system is basically a slightly modernized version of the '91 system made to accept R-134a natively, and it will all bolt right up to your '91. The lines are run in a straightforward way, and everything is easy to get to.

 

Copper is the better conductor of heat, but I can't tell you what that translates to in terms of real performance. I forgot that math a couple of years ago.

 

A parallel flow condenser is a good choice for any R-134a build, and IMO is required to get the most out of your system. The condenser in that kit does not look correct, though. The '91 condenser should have the lines connect "in line" with the core. The extra lines that come from the condenser and exit pointing down may be removable. In that case, that's no problem, and it will be another PF condenser option I didn't know about. The picture doesn't show the right angle for me to tell, though.

 

I used the APDI condenser available on Rockauto. It's working great for me after 7 months. It wasn't a perfect fit, but it was so close I wasn't even mad - one of the lines didn't quite want to fall into place. Please forgive all the $#!& that was in my bed when I took this picture.

As to the rest of the parts kit, here's where your choice lies. With that kit, you'll have a new compressor, which is good. It'll be offshore manufacture, which isn't "run away immediately" but it is "inconsistent." Now, I don't like "inconsistent" in my A/C compressors - that could mean that it's a sloppy build and will start turning itself to kibbles the second you turn the system on for the first time, or it might still be running fine 30 years from now.

 

There are a few reasons I chose to do my build the way I did. I insisted on an OEM compressor, which for this model is a Sanden SD7H15. The Sanden part number is 4727 for the '96 and 7701 for the '91. I have a terrible record with aftermarket parts, so your mileage may vary. On a lot of things, if you get a junky part you just swap it out. On A/C, that is far from the truth, and that's why we have to take this stuff so seriously - a compressor going all glitter bomb on you will take out the WHOLE system, with the possible exception of the evaporator. Of course, this is all dependent on the installer doing a good job too. Also, all of the parts will be specced for R-134a right off the bat - the lines will have the correct service ports already, the pressure switch is set for 134a, and so on. The only part you can't get brand new for the '96 system is the line from the drier to the expansion valve. That shouldn't be a problem to find from the junkyard, but you'll want to make sure it's in good shape. You'll want to have it flushed too. It's the smaller diameter one in the picture below.

 

Really, it's up to you. The big problem with any vintage A/C build is going to be parts availability. Lines are always a problem. I can only find the suction and discharge lines for the '91 system. That means one more part you'll have to source from a nearly 30 year old vehicle or have made from a pattern. Also, no faffing around with R-12 spec components, the manual service valves, or retrofit adapters.

 

If you go the '96 route, there is one thing that you'll need to address, and that's the oil filter. The later engines had the filter facing backwards, so that space was free for the A/C lines.

 

If you do go with the '91 system, let us know how the performance is! I would expect the 96 system to perform slightly better, but I really don't know.

 

As far as the topic of adding A/C to a truck that never had it, that's a gap in my knowledge that I hope someone here will be able to fill. I've always assumed that most of the infrastructure will need to be added. If you or someone else can come up with a list of what all needs to be added, that will be a valuable addition to the final product.

[JefCooks]

I just finished converting my ‘92 over to R134 yesterday if you want some help on the write-up. I pulled all the hoses and the condenser, flushed everything including the evaporator and installed new expansion valve and accumulator. I also drained the SD709T compressor and replaced it with Ester oil which is cross compatible. Rented a manifold, vacuum pump and flush gun for the project and got it all vacuumed down and refilled without problem. 

[Minuit]

9 hours ago, JefCooks said:

I just finished converting my ‘92 over to R134 yesterday if you want some help on the write-up. I pulled all the hoses and the condenser, flushed everything including the evaporator and installed new expansion valve and accumulator. I also drained the SD709T compressor and replaced it with Ester oil which is cross compatible. Rented a manifold, vacuum pump and flush gun for the project and got it all vacuumed down and refilled without problem. 

That's how you're supposed to perform a retrofit. You did good.

 

I'm not really at the stage where I'm ready to start writing it yet, but chances are I'll want a few other knowledgeable A/C people for fact checking, editing, and additional contributions.

[Minuit]

Hello thread from 2019, I'm just here to remind you that I haven't forgotten about this and am in a good position to be making progress on it as we progress towards the warmer part of the year - for most of us, anyway.

 

I did lose a huge amount of really useful information though - a website that had great info from highly reliable sources (and a few genuine experts and pioneers in the field) deleted their archives as part of an update sometime in the last year. That's info going back 15 or so years, just gone.

[ghetdjc320]

1 hour ago, Minuit said:

Hello thread from 2019, I'm just here to remind you that I haven't forgotten about this and am in a good position to be making progress on it as we progress towards the warmer part of the year - for most of us, anyway.

 

I did lose a huge amount of really useful information though - a website that had great info from highly reliable sources (and a few genuine experts and pioneers in the field) deleted their archives as part of an update sometime in the last year. That's info going back 15 or so years, just gone.

That’s a bummer! A write up would be awesome though. Especially as things start to warm up stateside