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I know this is not on a F-car but a similar era GM AC system I am starting to work on. Since I am running into the issues that most will trying to upgrade and rebuild their older GM A/C system, just throwing this up to show how to overcome the issues for the build and get a system that performs better than new, despite not running R12. The drop-in replacement condensers for GM vehicles this age have become a total joke in fitment and capacity. I am correcting that with this setup. I am upgrading it to get ice cold a/c and already know it will perform based off prior systems I have set up. My rule of thumb is a clean, well sealed evaporator core that forces all the airflow through it, the largest parallel flow condenser that will fit, efficient compressor upgrade and an orifice tube size adjustment.
I already swapped the engine to a L31 and used its bracket setup, tossed the junky R4 compressor to the side, removed the ancient, inefficient and damaged tube and fin condenser. I pulled the blower resistor, took a peak into the evaporator core housing, jam packed with leaves. New evaporator core, new blower motor. Bought a replacement condenser that was supposed to be a drop-in for the application but ended up being made wrong and was tiny compared to the available core support opening. I know parallel flows are more efficient but they made the drop-in unit smaller than the OE tube and fin by a substantial amount.
Since I would be fabricating mounts for it anyway and new hoses made up, took some measurements of the available space. Did some research and found a condenser for a Peterbilt application that will mount easily, has the correct #8 & #6 fittings, covers nearly the entire radiator opening in the core support and will mate to the OE liquid hard line. The Peterbilt replacement condenser core is 420 sq/in vs the 312 sq/in of the "drop-in" fit replacement. I actually contacted the company selling the "drop-in unit and their head of engineering only wanted to argue that it was in fact correct despite pictures showing it was not.
I will have the hoses made up in a week or two to mate to the Vortecs HT6 style aftermarket upgrade compressor and get it working. I am going to end up using a Sanden 4261 HT6 replacement based off the SD7H15 compressor that is a common replacement used. The OE vortec compressor mounted high pressure cutout switch is also getting wired into the compressor clutches ground circuit to cut the compressor should the ac high side pressure ever reach an unsafe pressure.
I am using a Vortec 4.3L S10 fan and heavy duty fan clutch for more airflow through the cooling stack. the more airflow you can move through the condenser the better. I also use a Ford Red 0.062" orifice tube in place of the GM White 0.072" tube on everything GM I run. Since many of us own other GM products, the GMT400 trucks with condenser mounted orifice tubes can also use an early 90s Cadillac FWD car orifice tube that is condenser mounted with the same 0.062" orifice as the Ford Red. R134a and R152a actually remove more heat per unit of refrigerant boiled in the evaporator, but need the refrigerant flow reduced so that the evaporator pressure stays at a lower suction side pressure, especially at idle. With the larger GM spec orifice tube the low-side pressure will not drop enough at idle and lower vehicle speeds to provide good cooling. The orifice tube size change is even something that has worked well in my OE GM R134a systems like my 97 Express and 99 Tahoe. I love being able to get ~30F air out of the vents before the compressor cycles even on a 110F day.
Given the Express and Tahoe are running dual evaporator systems and reach those vent temps with essentially the same compressors and similar sized condensers, the single evaporator system should effortlessly reach them as well and probably even have better idle cooling. I will take more pictures as I progress, but this is where I am at with the system at the moment.
I am basically starting over fresh with new system components and upgrading inexpensively where possible. The compressor itself will always be the highest cost item, more than the rest of the components combined, so it pays off to get a good quality unit and replace the other compenents at the same time. Cleanliness is probably the most important thing. If you plan to keep the hoses and hard lines be sure to flush them multiple times and blow them out multiple times to ensure all the flush solvent is removed. The flush solvent can contaminate the system if not properly removed resulting in poor performance and/or physical damage to the system. You also want all the mineral oil left in the system removed.
I intend to cover every aspect of this rebuild, from the tear down, fitment, fabrication, installation, flushing the hard line, to the actual evacuation, charging and cycling switch adjustment to get the coldest air possible.
I have not forgotten this rebuild. Just had to wait for parts and have been out of town. Headed to Colorado this week too. However an update on this custom build, ac refresh.
New evaporator core and blower motor installed, underhood HVAC case are re-installed. Orifice tube is installed and the liquid line flushed and connected. The condenser and evaporator core ends are capped off to keep things out of the installed parts. Last week, I ordered an inexpensive hydraulic actuated bead lock barrier ac hose crimper, hoses and fittings. Tested the crimper, crimping the two fittings on the discharge and suction hoses that will connect to the condenser inlet and accumulator outlets. I will cut the hoses to the final lengths before they are crimped to the universal Four Seasons 12034 ac manifold. Red Ford 0.062" orifice, part number 38635 is installed as well.
I was looking at one of those crimpers. Looks like it produced a pretty good result.
Seems like a solid result, very quick to setup, and easy to make the crimp. For my occasional use, no need to go buy a $550 US made equivalent when the $115 Chinese version should last me through multiple projects. It was also cheaper to buy the tool than pay the local AC hose shop to make the 4 crimps. Wanted $30 a crimp plus materials for 2 minutes of work.
Are you planning to charge this thing with R134 or R152?
I just did a full AC system on a G20 van a few months ago, and I used R134 and a Ford .067 orifice. It got really cold.
Since it is mine and I am the only one that works on it, R152A. The nice thing about that, if the vehicle ever gets sold, I recover the R152a completely, vacuum it a bit to make sure 100% of it is gone, then charge with R134a. Did that with my 2012 Titan that had R152a in it and my 2011 M56S. The R152a is a drop-in for R134a with no changes to anything. It should have different fittings, but I am not worried about anybodies recovery system getting contaminated with R152a because I am the only one working on these systems and I have my own inexpensive dedicated recover system for R152a. I bought a pair of old analog Robinair recovery units from the Nissan dealer I worked out that were tossed out because they had to buy computerized machines with temperature probes to print a little printout to make warranty claims. Memory serves me correctly, I only gave ~$150 ea for the old Red Robinairs way back in 2011ish. Anybody repairing ac on a regular basis needs a recovery/recycling unit and a functional, used system is a very budget way to get one. The old analog ones just seem to keep working as long as you change the recycling filters.
The G-vans usually do pretty well on R134a, but I feel like R152a will give it a little edge on a 115F day.
very cool ...I was thinking about revamping the AC on my '91 G30 box truck-the cab is partitioned off from the cargo box,so small area to cool.
Condenser is equivalent to part number 3S010633. Liquid line screwed right in after mounting it, but the compressor discharge hose has to be custom built. I would probably ditch the R4 with a rebuild and go with a Sanden anyway. The universal sandens are cheaper. The other possibility is using a V5 or V7 for a 2.2L S10 and adapting the R4 brackets to fit.
I picked up the bulk hose by the foot and fittings here.
https://coldhose.com/
Years ago,i had grabbed an R4 from a '95 S-10 as a spare-thinking the "bugs"had been worked out of the design after ~19 years of R4 production...Fittings at the back are slightly different on the 95 R4 as i recall-,I have some V5s and Sandens that could get deployed too.
Years ago,i had grabbed an R4 from a '95 S-10 as a spare-thinking the "bugs"had been worked out of the design after ~19 years of R4 production...Fittings at the back are slightly different on the 95 R4 as i recall-,I have some V5s and Sandens that could get deployed too.
The later R4s are better than the earlier ones, once you get past all the sealing washer/spacer stuff needed to adapt it to the manifold hose. That being said they still fail in the same manner as the older ones, blowing refrigerant out of the case seals, vibrate, rattle and eat power. Adapt over a V5 or V7, put the lowest pressure control valve in it and you are getting somewhere. V7 moves more refrigerant at full stroke than the A6 does and the V5 is just behind that. With proper control valve selection can hold the evaporator temperature near freezing without having to cycle. I start with the lowest pressure valve and work backwards if the evaporator tries to freeze with the V5/V7s. Much smoother operating compressors and eat a lot less power going down the road when they de-stroke.
I finished this project a while back. Even with the engine cover off, the ac gets very cold. It was about 85-90F when I charged it. With the engine at 2,000 rpm it got down to 29F out of the center vent before the compressor cycled. At idle the center vent was running about 40F and the RH vent right at the evaporator core, away from the engine heat was about 36F. System should work very well once the engine cover is on it and some weatherstrips are replaced.
I like the digital pressure tester....it even has a FUN button!
Great results though. 90* already down there....yikes. We were still getting snow last week.
Yea its getting warm down here especially in the afternoons. Snowed a couple of days while I was in Pagosa Springs last month. Was a fun trip.
Here is our forcast this week. One of the reasons I have gotten good at this ac stuff.
I cold started the van, before the engine heated up, it dropped to 36F out of the center vents at idle. Going to be plenty cold I feel. Might still be a smidge low on charge, but I will see how it does as it warms up here. Being a custom system have to charge off pressures and temperatures. I do need to pull the dash to gain access to some other stuff anyway, I will clean out the ducts and reseal them all while it is apart. The vents have a good bit of foam like material stuck to the back side of them, assuming it was the mesh behind the evaporator core that was missing that I replaced with the newer metal mesh and chunks of the duct seals. I can also feel numerous air leaks from the degraded foam seals between the ducting sections. I use closed cell foam adhesive backed weatherstrip and the high temp aluminum duct tape to seal them up. As it is probably blows 2x as hard out of the vents as my friends C10 the same year. I figure his has a dirty evaporator core and the blower motor is likely not getting good voltage. It is LS swapped but the wiring was not upgraded like this one was with a new junction block. The blower motor on this is only seeing a 0.3V voltage loss from the battery voltage.
My wiring no longer feeds off a 10 awg off the starter with the tiny undersized junction post typical of GMs of the era. It has a 6 awg feed off the battery and matching size charge wire off the 145a AD244 alternator. All fused with the correct gauge fuse links. Picture taken with the protective cover removed.
Since I finished up the engine work, wiring harness, header install and exhaust work, the engine cover went on and I have been driving it the last 2 days everywhere I go. Cools quickly and gets cold, especially cruising down the highway. It will get down to ~30F out of the center vents at highway speed. After the initial cool down, the 2nd fan speed notch is enough to stay cool in these sunny 75-80F humid days we are having. That was idling around town.
Fast,those are some impressive vent temperatures! Summer is already arriving here in south Texas.
I've got pretty much the same AC hose crimp tool that you have. I'm sure its made in the same china factory. It worked great for my custom fit hoses in my LS3 swapped, 1991 Foxbody Coupe. I'm getting sub 40F vent temps using R134a.
Fast,those are some impressive vent temperatures! Summer is already arriving here in south Texas.
I've got pretty much the same AC hose crimp tool that you have. I'm sure its made in the same china factory. It worked great for my custom fit hoses in my LS3 swapped, 1991 Foxbody Coupe. I'm getting sub 40F vent temps using R134a.
Is in north Texas too. Was sunny, warm and humid the other day, put 100 miles on this. I did end up having to turn the cycling switch adjustment in 1/2 turn as the evaporator was starting to freeze up with the air from the center vents reading a near constant 30*F
02-09-2024, 01:47 PM
