AC condenser upgrade / overheating

[Ecomike]

I am about to upgrade my AC condenser. I have an 87 XJ that I have converted to R-134a. It works fine up to about 88 F, but the recent heat wave (104 two days ago), and other issues (coolant / engine getting too hot), have me doing some upgrades. I have my coolant system temps under control with the AC off, but I like my AC!

My biggest remaining coolant and cooling problem is the AC now. The old R-12 condenser is just not up to the job for R-134a, in this kind of heat. R-134a needs a better, more efficient condenser (according to the experts). Seems the 97 XJ has just the ticket, stock! The 97 uses a 35% more efficient parallel flow condenser design, versus the serpentine flow design used in the 87 condenser. The 97 seems to be exactly the same dimensions as the 87. Main difference is the new style quick connect fittings on the tube ends on the 97, versus the old style threaded fittings on the 87, but I have a local AC hose guy close to me that does the hose / tube mods for the price of a couple beers.

Seems Chrysler upgraded to the parallel flow design condenser around 1997 as the stock standard part.

 

[winterbeater]

They probably changed from the tube fin design to the all aluminum brazed up condenser. Much more efficient, but much more prone to road debris damage. Not saying don't do it, but just understand that the aluminum tubes are about .0015" thick that keep the "freon" from leaking out.

 

[Ecomike]

They probably changed from the tube fin design to the all aluminum brazed up condenser. Much more efficient, but much more prone to road debris damage. Not saying don't do it, but just understand that the aluminum tubes are about .0015" thick that keep the "freon" from leaking out.

The AC condenser tubes are much thicker than .0015", as they must handle 400 psig peak operating pressure, and about 500 (or higher) psig burst. Radiators only handle about 20 psig. .0015" maybe what they use in the radiators now. Not much thicker looking than a sheet of thick paper. The old ones were all aluminum too, serpentine, not tube and fin so I already have the road debris problem.

The condenser difference is that the newer ones are built more like a radiator with a sort of tank (continuous tube about 1/2" diameter) on each end and multiple flat tubes of equal length in the core area connecting the sides. The serpentine design had one huge 20 to 30 ft long tube folded up that ran back and forth, side to side with a single super long tube, one inlet one outlet. I think the tubes are the same, just multiple tubes, instead of one very long one, from the drawings I looked at earlier.

Here is a good picture of the difference:

http://www.ackits.com/parallel/condenser1.jpg

 

[winterbeater]

Actually, you are correct in that they are thicker than the radiator tubes. I jumped the gun on that one. We were working on cutting down the radiator and condenser tube thickness, at my previous employer. The radiator tubes are rolled and welded sheet aluminum that was 0.0015 and thinner aluminum. The condenser tubes were extruded aluminum with multiple (like 5 or 6) parallel chambers. They were thicker than the radiator sheet stock. But they are much thinner than the old tube style and being aluminum, more subject to salt corrosion (shouldn't be an issue for you). We were experienceing a lot of evaporator failures from your area though, due to calcium chloride that is used on dirt roads to keep the dust down.

 

[Ecomike]

But they are much thinner than the old tube style and being aluminum, more subject to salt corrosion (shouldn't be an issue for you). We were experienceing a lot of evaporator failures from your area though, due to calcium chloride that is used on dirt roads to keep the dust down.

Did you mean condensers, or evaporators? How does salt get to the evaporators?

I have heard of evaporators problems, I just figured they were too thin, and or internal corrosion.

 

[Shorty]

I can't see where you would have any more problem with the late model condenser than any 97+ factory ac system. You will want to flush you current system doubly clean, though. In my experience, the newer style (parallel flow) condensers have much smaller passages that can easily plug with stuff that wouldn't "stop-up" the older tube design. If this happens, it is much more difficult to flush out the particulate also, as the flushing agent tends to bypass the obstruction and follow a free path through the condenser.

I will also be "upgrading" with the newer design if I find a need, but I'm still sitting on 60lbs of R-12, so it may be a while. Keep us posted on how it goes-- I'm definitely interested...

 

[Ecomike]

Well it is on order. Got one for a 97 XJ, for $107. True parallel flow. It is in transit now.

 

[winterbeater]

Did you mean condensers, or evaporators? How does salt get to the evaporators?

I have heard of evaporators problems, I just figured they were too thin, and or internal corrosion.

It shocked me too. Salt corroding the evaporators (not condensers). The condensers must get rinsed in the rain or something. It seemed the worst where there was debris like lint on the evap, then it held the salts and rotted through from the outside. As you are aware, evaps pull a lot of himidity out of the air. This is from warranty lab analysis that I monitored as an HVAC supplier. I can't say more due to confidentiality agreements. Bad results in the northeast US snow belt, but also southern states which use calcium chloride as a dust control. New car parts are "salt spray tested" using "sea salt fogging chambers", but not even tested with calcium chloride.

 

[Ecomike]

It shocked me too. Salt corroding the evaporators (not condensers). The condensers must get rinsed in the rain or something. It seemed the worst where there was debris like lint on the evap, then it held the salts and rotted through from the outside. As you are aware, evaps pull a lot of himidity out of the air. This is from warranty lab analysis that I monitored as an HVAC supplier. I can't say more due to confidentiality agreements. Bad results in the northeast US snow belt, but also southern states which use calcium chloride as a dust control. New car parts are "salt spray tested" using "sea salt fogging chambers", but not even tested with calcium chloride.

Interesting, I wonder if sulfur reducing bacteria in those wet humid conditions play a part. Copper is toxic to bacteria. I guess CaCl salt dust (fines) might get in there. It can't be just Cl ions, as they don't exist in the gas phase.

Did they use copper in the older evaporators? Mine is still OEM stock 87.

 

[winterbeater]

I did see some old ones which were copper brass construction. (From 2005 models which had not been redesigned for a long time.) This came back from being rotted also. Not sure about XJ, but I would suspect an 87 would be copper tubes and brass tanks.

 

[Ecomike]

Just a quick warning to future readers of this thread. The pictures of some 97 condensers on some web sites do not look like parallel flow. And I found one website showing both serpentine and parallel designs for 97, with a big price difference. Like $70 verus $140.

 

[88 Wagonman]

What about the expansion valve\block? Would it need to be upgraded?

 

[winterbeater]

It's all a carefully balanced system that might not work right when you mess with it. But people make major changes like the refridgerant from R12 to R134? and it usually works.

 

[heavyequipment]

The parallel condensors are better. The expansion valve would be the same with either type of condensor.

 

[Ecomike]

Well the new PF, AC condenser I ordered (second attempt, first place I ordered from sent me the wrong one) has arrived. It is a #640129PL, from www.ackits.com , and this is the right one, a true parallel flow, high efficiency condenser, it is the PF listed for a 97 Cherokee, XJ on their site . It should cool about 40% better than the old style in my 87, and my 87 condenser is showing its age, so I might get a 70% improvement out this. Cost $145.30 delivered.

It has twice the tube density (# of tubes) vertically, the tubes are half, to 1/3 the thickness of the tubes in my old 87 condenser, and the core is half the thickness of my old condenser! So this should be interesting.

The length and width of the new PF condenser are a pretty close match to my old one. And it comes with the metal lines that wrap around the radiator on the passenger side. Next step is take it to my AC hose buddy and get adapters made up to go from the round QC fittings on the new condenser to the threaded fittings I have on my new hoses.

 

[88 Wagonman]

I am anxiously awaiting your results. I have an 88 that I would like to upgrade as well.

 

[desertred]

Make sure you post the results once you get it all hooked up. I have a 88XJ that I converted to R134a a few years ago, and it has never cooled as efficiently as the old R12. Maybe I could benefit from your upgrade. With the recent 100 degree (or near) temps we've seen here the last few days (and will see for the next week or so), stonger a/c will be a blessing.

 

[Ecomike]

Ok folks, the great Ecomike experiment with upgrading an 87 XJ AC to a 97 XJ parallel flow condenser was an outstanding success.

Only took 17 oz of R-134a to get 45-50 F cold air at the vent, 90 F ambient, and the pressures were only 48 psi low, and 215 psi high. A far cry for 330 psi high pressure it was hitting. The condenser is holding about 130 to 135 F with 90 F ambient.

I also installed a CSF 3 row all brass radiator, and I am holding about 180 F at the thermostat housing now, MAX!

Other upgrades which I did at the same time, included adding an inline filler neck to the upper radiator hose, which helped get the trapped air out of the radiator (Renix system, closed coolant system).

This condenser was well worth the money, knocked my top end AC pressure (high side) down a good 35 to 40%, and my AC now blows about 15-20 F cooler than it did before. Big difference between 50 F and 65 F!

Oh, and I did not buy the universal one from ackits.com mentioned below, I found a true parallel flow OEM style for a 97 XJ, that is an easy, direct retrofit(1). The place I bought it had 2 styles, one was a serpentene, about $70, the other a parallel flow for about $140, both OEM style fits. Be warned though, that you will need to get an adapter fitting-hose assy made custom to connect the old threaded fitting set up to the new condensers quick connect used on the newer AC systems. I got mine made up at a local ac shop that custom makes AC and brake tubing and hoses on the spot, for about $20 to $30.

 

[88 Wagonman]

Those are some good results! I guess I'll have to look in to doing this myself before next summer. Anything that you can post up would such as part numbers, fitting sizes, etc. would be very helpful. Also, what brand of r134-a did you use? I have often wondered if there is a difference in performance between brands. If anyone would know it would be someone with your background in automotive chemicals I would think. Anyway, congrats on the successful upgrade.

 

[Ecomike]

I seem to have lost the paper work on the one I bought, but here is one that is little less than what I paid, but it is the right one, Part #P40129P:

http://www.thepartsbin.com/repsite/jeep~a-fs-c_condenser~reparts.html