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Username Post: A/C How I did it.....        (Topic#168431)
FERG 
Frequent Contributor
Posts: 1115
FERG
Loc: Wylie, Texas
Reg: 05-22-03
08-28-07 03:29 PM - Post#1241763    

Basically when I started my project I had an evaporator core and the blower motor under the hood and that was it. The rest of the A\C components were removed by a previous owner, presumably for HP gains. I started by checking out several online sources and figuring out what I was missing and what I had that might be reusable.

One online source I used was LMC's catalog; it provides a decent exploded view of the system...


The best online source I found, thanks to Vaughn, was the A\C Forum . These guys know their stuff and offered endless amounts of info. I literally could not have tackled this project without them.

The next thing I had to do since I was starting from scratch was to decide whether to go with the old R12 refrigerant or the newer R134a. After talking to several people they recommended the R12 since it was what the factory used. However I also learned that it's hard as all get out to come buy and priced higher than gold. Plus it was harder to find UV dyes, gauges or anything else I might need to work on the system. So simply for the sake of convenience I went with the R134a. To date I have not regretted the decision, it blows plenty cold and I have not been able to tell any difference at all in the two.

I figured out that I was going to need the low side and high side hoses, a compressor, compressor brackets, orifice tube, accumulator\drier, and an evaporator. And of course some oil and refrigerant which I'll get into later. I bought most everything new the only two exceptions were the lower hose from the evaporator to the condenser and the compressor. The compressor I picked up on the cheap at a junk yard, which I later learned can be a big mistake. The lower hose that I needed I couldn't locate new anywhere, nor could I find the right year model at the junkyards. The one place I located online that would make it wanted nearly $200 for the hose. So I found a different year model that had the same size fittings at a junk yard but the hose was all bent metal tubing. I cut the tubing in the middle and used a piece of rubber tubing and some hose clamps to mock up what I needed the hose to look like in the end. I took the mock up to an A/c shop and they put on the proper type hose and fittings and made the hose I needed with my old fittings for $60 and it tool them all of 15 minutes or so.

After collecting all of my parts and my custom hose I went home and started trying to figure out where everything goes. The hardest part was figuring out the pile of brackets for the compressor I got from the junkyard. I ended up with some time constraints from work and family and took the truck to a guy my dad knows that does mechanic work on his day off out of his house, big mistake number two. He put everything together for me and charged the system with an r12 substitute called freeze12. It was blowing cool but certainly not cold. I was disappointed to say the least and he didn't seem to enthusiastic to help figure out why the system I had paid him to get working wasn't working like it should.

That's when I found the guys at the above mentioned a\c forum. They wanted know what kind and how much oil he had used as well as what type and how much refrigerant. The "mechanic" didn't know, just said that he used a whole bottle. Later I found out he used PAG46 in my at the time r12 system. A BIG NO NO!! You can't mix the mineral oils for an r12 system with the PAG46 oil for an R134A system. Plus he didn't flush the system prior to putting it all together. WHICH IS A MUST!! Especially using a junk yard compressor that had been sitting on a shelf for who knows how long and the evaporator already in my truck that had been sitting open to the atmosphere for equally as long.

So I disassembled everything I paid him to put in so I could flush out the mixed oils and any debris. I can't stress enough how important this is.

How to flush the system:

1. You can't flush the accumulator/drier it must be replaced
2. Do not put a solvent in the compressor. You use the new and proper oil to flush out the old. Turn the compressor pulley face down and pour in two to three ounces of oil. Since I was now switching to R134a I used PAG46. (OE
spec calls for PAG150 which was later found to be to thick so then they recommended PAG100 which was still too thick and now the PAG46) Place the compressor in a bench vise using the small compressor brackets as a bite point. Place a socket wrench on the bolt head in the center of the pulley and a cup at the back to catch the mess your about to make. Turn the bolt head and it will cause the compressor to compress and start pumping fluid. After you have pumped all of the fluid out, refill it and do it again. Then do it again. It is crucial to ensure you have all of the old fluid out and any debris in the compressor out as well. Once the compressor is cleaned out and empty of all flush oil, refill it with the proper amount of oil for your year model and compressor. (Note: around this time I read something on the a\c forum and figured out that my junkyard compressor was bad, so I picked up a remanufactured one from o'reily for $139 it was the best price I could find)

Here is a chart. Simply scroll down to your year model and compressor type. These listings are for R12 systems on our trucks. The oil capacity will not change if you convert to R134a, but the refrigerant amount will, more on that later... A\C system capacity

3. Everything else can be flushed with a solvent that has a high rate of evaporation. I used a gallon jug of paint thinner, under the advice of the a/c forum, and it worked very well. You have to flush each component individually. TO do the hoses I removed them and poured in some solvent. Then using my thumb at either end I would let the fluid run from one end to the other, and then back again. I did this several times then poured the fluid out. I would then refill the hose and do it again. After two to three flushes, I used my compressor to blow out any residue. Then I'd blow it out some more.

Any remaining solvent residue will thin out your oil when you put the system back together so get it good and dry .

Then I turned to the evaporator and the condenser. I used the same process on both of these pieces. I left them in place in the vehicle and used a flexible funnel with a tapered end to fit the openings. I poured in the fluid and used the compressor to blow it out. Start with the lower opening and then the higher opening. After I blew all of the fluid out. I poured in some more solvent and did it again. Since the condenser was new and had only been run for a week or so I didn't clean much debris out, but the evaporator had a lot of build up in it and it made a big difference in air flow through the piece. I flushed the evaporator two more times before I felt comfortable with it. Then made sure it was all well blown out.

Then just reinstall everything, be sure not to forget your orifice tube and new o rings. Be sure to install the accumulator drier last as it does not like the moisture in the air. After everything was installed I had to finish the R134a conversion. These are basically the fittings where you connect your gauges. The original connections for your r12 are welded in line near the evaporator and the other is on the accumulator. YOU HAVE TO REMOVE THE OLD VALVE CORES! I didn't do this the first time and it caused some problems. You can get the valve core removal tool at NAPA. The one I got was for tires (they were out of the ones for A|C), so I had to use a file to file down the end of the tool and make it small enough to fit in the opening. After unscrewing the old valve cores, just screw on the r134a fittings, for added reliability I used some thread tape on the threads.

Now that everything is cleaned, installed and converted you need to draw a vacuum on the system to boil off any moisture. I tried using a harbor freight A\c vacuum with my compressor but didn't get the results I needed. I called a local mechanic shop (a reputable one this time) and they normally charge $80 plus Freon at $22.50 a pound to vacuum and charge the system. But I told them all I needed was to pull a vacuum and check for leaks. So they obliged for $30. Then I bought 4 cans of R134a with the UV dye already in it (in case of a future leak) for $26 total. To charge the system you have to unplug the pressure cutoff at the accumulator drier and use a piece of wire to jumper the connection. Then hook up your gauges to the proper ports and attach the can to fill with. Start the truck and turn the system on. Fill the system to 50% capacity, then slowly add one ounce at a time till you reach optimal cold temp at the vents in your dash. If you made the conversion to R134a you will generally stop at about 80% of the total recommended. This stuff expands more and needs the room, from what I have read. If you put the full amount of what was recommended for the R12 system, it will start blowing off hoses and what not. If you didn’t' make the conversion and decide to use r12 or it freeze12 replacement then use the full recommended amount. (The recommended amounts are on the above listed system capacity chart)


Now, roll up the windows and cruise with that sweet sweet cold air blowing in your face.....

I hope I was able to effectively convey the necessary info to get you on track. If not feel free to drop me a line and I can clear up anything or point you in the right direction of someone that can.

Helpful link:

Auto A\c Forum - be sire to read through their Tips and FAQ's a lot of what you need is in there already. Then go ask questions, be sure to have all of the info they ask for on their form it's very important for people to be able to help you.

Also, I forgot to mention you will need a GOOD set of ac gauges, not the cheap ones. Although they work, most can't read the vacuum, just the pressure. I have and old set of R12 gauges, I flushed them out like I did the system and bought the r134a adapters for about 40 bucks. A new set of r134a gauges can run from 80-150 or higher.


GOOD LUCK,
Craig




Edited by gchemist on 08-28-07 05:39 PM. Reason for edit: No reason given.

 
NC-vector 
Member
Posts: 263
NC-vector
Loc: north carolina
Reg: 12-21-06
08-28-07 05:27 PM - Post#1241834    
    In response to FERG

I like the fact you tackled the stock system, and used the R134A.........did you ever think aftermarket.........what was the total cost? or difference?

good job!



 
gchemist 
Senior Chevytalk Moderator
Posts: 24420
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
08-28-07 05:38 PM - Post#1241845    
    In response to NC-vector

The A/C in my truck did not work when I bought it. I switched it to R134. It blew ice cold even at the lowest setting. I had to turn off the A/C going at highway speeds because the lowest setting would freeze my n*&&#%s!! The A/C worked great until the compressor failed. I've replaced the compressor twice. The original type of compressors hard to come by or the unit I've bought had poor jobs done on them. Nice write up.
I'm making this post a sticky.

'95 Jimmy SLT (Bought @131,814)
'83 Silverardo XST - ZZ4 powered
'96 GMC Jimmy LS Ret. @236651 miles


 
FERG 
Frequent Contributor
Posts: 1115
FERG
Loc: Wylie, Texas
Reg: 05-22-03
08-29-07 05:54 AM - Post#1242119    
    In response to gchemist

Thanks!

Didn't really want to mess with the aftermarket systems. Most I saw mounted the vent below the dash. I wanted everything to look pretty stock. Total cost was around $1000 for everything including what I paid the shade tree mechanic. From what I have guestimated, I still saved around $800 or so in labor.



 
SMF Innovations 
Senior Member
Posts: 331

Age: 31
Loc: North Carolina
Reg: 10-11-04
09-08-07 02:36 PM - Post#1249301    
    In response to FERG

I need to do my A/C system in my 85. Everything from the stock unit is there but my compressor is froze up that is all. I had a deal on a Holley remanufatured compressor (same style as the stock 85 Chevy) for 50 bucks but didn't get it. I may still be able to. I am thinking that if I got that, the PAG oil, R134 refrigerant, a orfice, and dryer and new belt I should be good to go right?
Say that I cannot get that compressor still, what other options do I have? How much is a brand new one that is GOOD because I hear sometimes that the ones from auto zone or such are not that great.



 
FERG 
Frequent Contributor
Posts: 1115
FERG
Loc: Wylie, Texas
Reg: 05-22-03
09-25-07 04:40 AM - Post#1260883    
    In response to SMF Innovations

Was it already converted to R134a? If so, then you should be good to go. Be sure to flush the system. Even though you put the oil in the compressor, it gets distributed through out the system. If your compressor froze up, you probably have some "black death" in the lines( the a/c forum link has info on black death). I would spend the extra time to flush it now, and save yourself the trouble of having to redo it and possibly replace a new compressor.

It's not that the Autozone compressors are that bad. The sanden compressors that most of these trucks used were just a poor design and under built. I have used a remanufactured compressor on another 70 chevy I had and it ran fine for 2 years that I had it.



 
tony1963 
Frequent Contributor
Posts: 1206

Loc: Birmingham AL
Reg: 10-11-08
12-14-08 06:14 PM - Post#1584857    
    In response to FERG

I retrofit my 85 C20 Suburban several years ago. I replaced everything, evaporator, condenser, lines, compressor, etc.

Works quite well, but in HOT Alabama weather, it warms up at idle.

1964 Chevrolet Impala SS 327 Powerglide (SOLD!)
1981 Ford Granada 3.1 L (200 inline 6) (SOLD!)
1985 Chevrolet Suburban C20 454 Turbo 400
1999 Mercedes E300 (SOLD!)
2008 Mercedes E350
2012 Mercedes S550



 
wizard28 
Forum Newbie
Posts: 27

Reg: 04-17-09
04-17-09 05:11 PM - Post#1678850    
    In response to tony1963

I'll need to replace everything for a/c in my 86 besides the condenser.


think itd be cheaper to get the parts off junk yard chevys (in which case what years) or go for the lmc type way.



too bad I cant just take my 83 bronco system out, or could I... ? haha



 
blg4351 
Forum Newbie
Posts: 87
blg4351
Age: 38
Loc: FT. Eustis, Va
Reg: 04-19-09
06-29-09 07:38 PM - Post#1726157    
    In response to wizard28

When you flush the system should you take out all of the components of the system. Can you do it with everything still installed? I called around to some places in my area and all they said was that the compessor lines just need disconnected and that they could do it.

85 K5 4x4, crate 350 headers and holley 600 4 barrel. 700R4 np 208 transfer.


 
FERG 
Frequent Contributor
Posts: 1115
FERG
Loc: Wylie, Texas
Reg: 05-22-03
07-01-09 12:52 PM - Post#1727196    
    In response to blg4351

It would be easier if they were out. The compressor will be especially difficult if it's still in the vehicle.



 
blg4351 
Forum Newbie
Posts: 87
blg4351
Age: 38
Loc: FT. Eustis, Va
Reg: 04-19-09
07-18-09 10:43 AM - Post#1737336    
    In response to FERG

Cool i got a new condensor accumulator and a compressor the other day. So i should use pag46 to get the new compressor up and going? I looked at the chart and its say mineral oil but it was once converted to 134a already. I pulled the lines off of the compressor to notice some nice black soot coming out. I am going to flush the whole system with the paint thinner and blow it all out with a air compressor. So when re-applying oil with the 134a how much should i use?

85 K5 4x4, crate 350 headers and holley 600 4 barrel. 700R4 np 208 transfer.


 
FERG 
Frequent Contributor
Posts: 1115
FERG
Loc: Wylie, Texas
Reg: 05-22-03
09-08-09 06:20 AM - Post#1768105    
    In response to blg4351

Check with the guys at the AC Forum in my post. They will have specifics, it's especailly important when doing a conversion.

From what I have read it's 8 oz of oil pag46 or mineral and 48oz of r12 so use 80% of that when doing r134a



 
62chevy427 
"12th Year" Silver Supporting Member
Posts: 2126
62chevy427
Loc: laurens sc
Reg: 04-13-06
04-12-10 11:25 AM - Post#1897265    
    In response to FERG

my truck,83 gmc 4wd, did not come with ac. i purchased another truck for the ducts and wiring harness and bought new condensor,evaporaor and compressor.took a while,but works well. i did use r12 since i bought a bunch before it got unreasonable.



Attachment: IMG_0604qa.JPG (35.97 KB) 721 View(s)

56 bel air ((since 2002)
62 impala ss (since 1965)
65 el camino (since 1969)
66 nova (since 1987)
67 malibu convertible (since 1981)
72 el camino ss454 (since 1985)
83 gmc 4wd (since 1991)
95 impala (new)
14 camaro (new)


 
FERG 
Frequent Contributor
Posts: 1115
FERG
Loc: Wylie, Texas
Reg: 05-22-03
06-17-10 09:33 AM - Post#1931721    
    In response to 62chevy427

Another thread to check out before you get in to changing over your system....

CONDENSOR



 
kangaroo 
Member
Posts: 234

Reg: 11-04-06
09-10-13 05:27 PM - Post#2380873    
    In response to FERG

thanks for taking the time to post. I have spent about 1500 hundred in the last 2 years and still have not made it thru 1 season where the AC doesnt fail. I have went thru 3 accumulators , 3 compressors, and about 4-5 times paying to recharge the system. The system is down now also. It cools but quickly goes warm. If I stomp on the gas it will cool again but does not last.



 
62chevy427 
"12th Year" Silver Supporting Member
Posts: 2126
62chevy427
Loc: laurens sc
Reg: 04-13-06
01-17-14 10:00 AM - Post#2417577    
    In response to wizard28

my 83 gmc did not come with ac. i bought a 73 truck and used everything except the hoses,condenser,evaporato r and compressor. looks and
works like it came in the truck.
my point is that the parts will pretty well interchange between 73 and 87.
there are some changes in the control head,but all that can be worked out
i do not like the aftermarket systems. i have installed some in cars for customers and was not impressed with the quality of the inside vents,hoses. the compressor,evap,condenser seemed o.k.

56 bel air ((since 2002)
62 impala ss (since 1965)
65 el camino (since 1969)
66 nova (since 1987)
67 malibu convertible (since 1981)
72 el camino ss454 (since 1985)
83 gmc 4wd (since 1991)
95 impala (new)
14 camaro (new)


 
kangaroo 
Member
Posts: 234

Reg: 11-04-06
05-24-14 07:14 PM - Post#2455671    
    In response to 62chevy427

Any one know a reputable AC guy in North Texas? I need my AC done ASAP



 
kangaroo 
Member
Posts: 234

Reg: 11-04-06
05-23-15 11:40 AM - Post#2549193    
    In response to kangaroo

  • kangaroo Said:
Any one know a reputable AC guy in North Texas? I need my AC done ASAP


LOL, Im still looking. I have taken it to two different places and they tell me its working fine. I get in the truck drive a few miles and it blows cold then starts blowing warm again. I actually just picked it up from the shop . Same issue , gauges read fine but down the road it starts to blow warm again. I floor the gas and it starts to blow cold again.



 
CowboyTrukr 
"7th Year" Silver Supporting Member
Posts: 4017
CowboyTrukr
Loc: Salt Lake City
Reg: 06-20-09
05-23-15 04:07 PM - Post#2549243    
    In response to kangaroo

Roo, you may just need the low pressure cutoff switch.


Greg

'95 K1500 Z71 EC Short Step 5.7L+0.040/NV3500
'00 Explorer XLT 4.0 V6 Auto
'94 K2500 5.7 NV4500 ECLB - SOLD
‘87 GMC S15 SCLB 4.3 Auto - SOLD

"The only thing necessary for evil to triumph is for good men to do nothing" Sir Edmund Burke


 
gchemist 
Senior Chevytalk Moderator
Posts: 24420
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
05-24-15 07:45 AM - Post#2549325    
    In response to CowboyTrukr

It may be time to go to a trinary switch. I'll be updating my sytem with a Saden 508 compressor. I'm removing the stock low switch. A trinary switch will for high and low. An added bonus is a signal for my electric fans.

Where in N Texas?

'95 Jimmy SLT (Bought @131,814)
'83 Silverardo XST - ZZ4 powered
'96 GMC Jimmy LS Ret. @236651 miles


 
kangaroo 
Member
Posts: 234

Reg: 11-04-06
06-04-15 07:39 PM - Post#2552278    
    In response to gchemist

I believe I got it fixed. 2 hot summers and 2 shops and another 3-4 hundred dollars later and I ended up fixing it myself.

I adjusted the air gap on the clutch and now it stays on with out cutting off. I did not think it would work since the gap was .020 and I only moved it to .014. Now the clutch engages and disengages like it should.



 
Raven18940 
Member
Posts: 450
Raven18940
Reg: 09-22-04
07-16-15 10:16 AM - Post#2562166    
    In response to kangaroo

Hey, quick question since it seems like you guys would know. If you're just topping up a R12 system that's already been converted to R134a, at what pressure is the system "full"? I know there's a window on gauges you get at the cans on the autoparts store. Example it was ~70 outside and the windows was 25-45psi. I filled it to 35 but it's not super cold yet. Should I put more in and get it up to over 40?



 
kangaroo 
Member
Posts: 234

Reg: 11-04-06
07-24-15 04:30 PM - Post#2563822    
    In response to Raven18940

I dont think any one can answer that. Every where I looked said you will need gauges to fill it accurately . To much or to little and you can burn something up in the system. Really its added by weight and with out knowing how many ounces are in there all ready is a little more difficult.



 
bry593 
Contributor
Posts: 806

Reg: 10-07-13
02-05-16 11:40 AM - Post#2606855    
    In response to Raven18940

Pressures vary with temp and humidity. The surest way is to vac the system and then charge 80% with R134.

Btw, to flush an R12 system, you use Acetone (Lowes) in a flush can. A flush can has a schrader valve so you can pressurize it with your air compressor. Once the fluid exits without discoloration, blow out the component (condesor, evaporator and hoses)with compressed air. Any remaining acetone will quickly boil off when the vacuum is applied.

Hoses should be replaced with modern barrier hose if you want the 134 to stay put. You should also replace all o-rings with silicone.

Obviously, you will need a new accumulator/drier.

A new compressor is a good idea and 10-cyl aluminum versions are available at RockAuto to directly replace the A6 (long style). That's right, it bolts to the factory brackets and fits the factory hoses. Careful, you may need to shim at the bracket to compressor interface if there is a gap.

I only use Ester oil which is compatible with mineral and PAG.

Note you should change the plastic orifice tube pressed into the evaporator inlet to one calibrated to R134.

This will last a good while and will cool fairly well. It will never be as good as when used with the original design intent, R12.




 
kangaroo 
Member
Posts: 234

Reg: 11-04-06
07-09-16 06:54 PM - Post#2638807    
    In response to bry593

  • bry593 Said:
Pressures vary with temp and humidity. The surest way is to vac the system and then charge 80% with R134.

Btw, to flush an R12 system, you use Acetone (Lowes) in a flush can. A flush can has a schrader valve so you can pressurize it with your air compressor. Once the fluid exits without discoloration, blow out the component (condesor, evaporator and hoses)with compressed air. Any remaining acetone will quickly boil off when the vacuum is applied.

Hoses should be replaced with modern barrier hose if you want the 134 to stay put. You should also replace all o-rings with silicone.

Obviously, you will need a new accumulator/drier.

A new compressor is a good idea and 10-cyl aluminum versions are available at RockAuto to directly replace the A6 (long style). That's right, it bolts to the factory brackets and fits the factory hoses. Careful, you may need to shim at the bracket to compressor interface if there is a gap.

I only use Ester oil which is compatible with mineral and PAG.

Note you should change the plastic orifice tube pressed into the evaporator inlet to one calibrated to R134.

This will last a good while and will cool fairly well. It will never be as good as when used with the original design intent, R12.


any info on this aluminum unit? That sounds great . My AC is working perfectly now , but when the compressor gives up I would like to upgrade.




 
louismz 
Forum Newbie
Posts: 5

Reg: 07-25-16
08-10-16 08:17 AM - Post#2644958    
    In response to FERG

Another option is to use Redtek 12a refrigerant. It's compatible with both R12 and R134a systems, supposedly more efficient and operates at lower pressures than the R134a.

I just used it in my RV/G30 van and am getting around 58 degree temperatures at idle with an old compressor. I recharged the system with three six ounce cans which is equivalent to 3 lbs of HFC 134a and 3 lb 6 oz of CFC 12. Cost for three six ounce cans was $37 plus the can of oil recharge which was $21.95.

Time will tell how it holds up!





 
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