CK5
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Wintertime AC

Condensor on my Suburban is large. Almost as big as my 41" radiator. It also has 2 large evaporators. Front is something like 14" x 18" and rear is something like 18" x 24". Of note, GMC models were using R134a starting in 93 as opposed to Chevy ( 95-96) who knows why. Don't know too much about this new type of compressor, you suggested I use largest possible, do you have any ideas or suggestions as to which ones are larger?
 
It makes sense that a rear air unit would have a bigger condenser, but I have never worked on an older vehicle with rear air. The oldest rear air burb I have worked on was a 97, and I dont remember if the condenser was the same or not. Still, you are ultimately limited by compressor capacity.

Both the Zexel/Seltec and the Sandens are 150cc displacement compressors (the "15" in their respective model numbers denotes displacement in cc's x10), which equates to about 9 cubic inches. The R4 by comparison is an 11 cu. in. compressor, so it has about 22% more displacement than the replacements. A more efficient condenser will allow the 9ci. compressors to do pretty well, but you will still suffer some performance loss, especially with 134a. The only way around that is to use an R4 compressor and/or R12 refrigerant :doah:. Personally, unless you have rugrats riding in the back and use the rear air a lot I would still go with the Zexel or Sanden replacement. Ultimately, it's your choice though...
 
Excellent information as I'm needing to redo my A/C. It does not blow cold and the compressor is making noise when engaged.

My question to you is will the old r12 style gauges be of any help when doing a 134a conversion? I've seen some at the pawn shop for $25.
I ended up with a quality set of R-12 gauges from Pawn shop for $15 and then got adapters to 134a for another $15.

Then years later tried the special secret blend of freon... it's cheap, works on all systems, mixes with any oil, works great! Blows colder then R12 or R134a. Everone said you can not use Propane! This secret blend sold under many names is not propane, on the label for ingredients it is LPG! :whistle:

Anyway it worked all summer no issues...

Subscribed.
To a very old thread... :doah:

It's great info though! :D
 
... he has a condenser from a late-model S-10 (it's a super-efficient parallel-flow type). His AC blows cooler and runs 75-100PSI lower head pressure than mine. I plan on swapping my condenser out for one like his when I do my engine swap.
I'm confused on this because I measured my condenser at something like 15.5x30", but the S-10 ones are 14x26". 30% more effecient does little more than make up for 22% less surface area. The AC Delco replacement unit (15-6960) is even smaller - only 24" wide. :confused:
 
Remember, you are thinking of the surface area as the surface of the condensor, not the surface area of the actual piping. In a parallel flow type unit there is more surface area in the piping than the older tube and fin design that our trucks use. Even though the unit is slightly smaller than our old ones, it is far more efficient and has more surface area due to the wide flat piping that it uses.
 
Sure, the added efficiency comes from the extra surface area - more gas is touching metal at all times - and parallel paths (hotter gas is spread out over more area), but it's not proportionately that much more area directly exposed to the air flow. I've never found any real numbers except the 30% efficiency figure. None of those statements said anything about saving space or making the unit smaller. AC Delco talks about saving weight with their "replacement" unit, but never mention improving performance. What is the definition of condenser efficiency, if it's not amount of heat removed at a certain refrigerant and air flow?

It only makes sense that the replacement units would be parallel flow, as that's what the factories will be set up for. They save on extra tooling and save on material.
 
Propane still blowing cold for second summer! :D

I imagine the only reason why NOT to run propane would be the potential for an explosive environment should you ever spring a leak... I dunno if the other refridgerants are flammable or not.

Interesting thought though!
 
It's what is used in Europe where Dupont has no control... ah I mean lobbied the goverment.

Flash point of propane... ah, I mean LPG with oil is lower then R12R/134 with oil.

It was installed in stock 1990 Suburban system with nothing more then fix a leaky shrader valve, vacuum system and charge. Charge is less pressure then R12 to put out 34 degrees at vents.

The stuff I got at a craigslist garage sale was Envirocare.
 
Yes, the head pressures are lower, which is easier on everything and should leak less, although I don't know how the HC molecule size compares to the CFC.
 
Me either, that's why I was worried about re-charge each year. So far second year no re-charge. My AC also comes on all winter with defrost so system get's used all year.
 
some people seem to get wound up about propane but they are riding around on 20-50 gallons of gasoline.
 
Never seen or heard yet, of a vehicle explosion from leaking freon from front end collisions anyways, even just had a friend of mine smash the crap out of his S-10 a few weeks back, and we had just topped off his r-12 system about 2 weeks before this crash, his truck didn't blow up.

I keep hearing about flammability issues with different freons, I have yet to see flames from them under the typical every day use we put them through.

I know freeer warehouses use ammonia for reefer units, obviously a nasty chemical, but does real good at refrigeration.

And 34 degree vent temps,? I dunno, maybe these are old temps that people are used to from older 70's equipment, but so far, every newer vehicle I have been in, usually has a single digit temp coming out of the vents.
 
ammonia isn't that bad, we put it on our fields and I have worked in a NH3 plant and AN plant. Beats Hog poop.
 
I don't know, I just saw all sorts of ammonia alarms throughout the place, just assumed it was pretty nasty if a leak had occurred that they needed to evacuate the place. Could have sworn I had seen some stuff on TV as well with rail cars hauling it, crashing & leaking.

Not sure how it couldn't be bad.
 
They are fazing out R-134a. The new is R-1234ya. In the training for the new stuff, it is "slightly flammable". This has started to be used in 2011 and 2012 cars.
 

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