Notes from my a/c conversion

J

JDEstill

Turboliscious!
Joined
May 26, 2001
I did my a/c this summer. I’ve been meaning to write up some notes that could help some others who are doing something similar, since I had a few hurdles to overcome.

I replaced my compressor, my condenser, orifice tube, and accumulator. I reused my hoses and evaporator. The condenser is a generic parallel flow unit that I got, since I didn’t turn up any drop-in parallel flow condensers (though I since learned that the one from… Rock Auto? is close.) I wanted a condenser that could get me max cooling in this Houston summer heat and humidity if I converted to R134a (I actually used a different refrigerant though).

I used the stock orifice tube, which is white.

I used this condenser:
http://www.ackits.net/index.php?route=product/product&path=85&product_id=35742

I used this refrigerant:
http://www.es-refrigerants.com/prod...ial-r134a-replacement-refrigerant/details.asp

Worst part of the whole conversion was getting the condenser mounted and the lines connected, that took me quite a while. I can provide details to anyone interested. And if I knew then what I know now, I wouldn’t have done it the way I did it! :)
 
Flushing – First time around I used a whole can of brake clean to flush out the lines and evaporator. The evaporator was still in the car. The system had some green dye in it from several years back.

I sprayed the brake clean into the evaporator, let it soak a bit, then blow it out with my air compressor. At first the stuff that came out was really green, but by the time I ran out of brake clean there was just the faintest hint of green, so I thought it had done a good job. I then blew the heck out of the thing, trying to get all the brake cleaner out. When nothing else was coming out I started to put my thumb over the outlet and hold as much pressure as I could, then when I pulled my thumb off I would get an explosive depressurization that carried some more out. Finally I just could not get anything else out. It had to be all dried out. So I put some PAG oil in it, buttoned it up, and started to vacuum it out.

I let the vacuum pump run a while, then left it to sit so I could watch the pressure and make sure there were no leaks. No change after an hour. After two hours the pressure had gone up some, to maybe half vacuum. Started pump again and the vapors that came out smelled like brake clean. Now I found this to be very odd. Brake clean evaporates so quickly I never would have thought it would be able to stick around under vacuum – or even after blowing the evaporator out as much as I did. But it seemed like some was still there. Vacuum stayed steady though, and I left it for the night. Next day I vacuumed it some more, and got that brake clean smell one more time. But then it held vacuum really good for a few more hours, never creeped up again, and I deemed it done.

A week later, my brand new compressor was dead and I had to go through everything again. When I dumped out the week old oil from the accumulator, it smelled like brake clean. Did contaminated oil kill the compressor? Maybe, though could have been a coincidence… Again, I never would have guessed that brake clean could hang around under vacuum. But… if there was some liquid brake clean left in the evaporator despite all the blowing out that I did, and I then poured some oil in there, the oil might have absorbed it and would not let it go even under vacuum. That’s my best explanation for what I saw.

My takeaway from this is:

  1. Probably the best thing to do is take the evaporator out of the car so you can really drain it. Though I got mine working fine on the 2nd attempt without doing that.
  2. I would recommend flushing it, then vacuuming it out *before* putting any oil back in. I did this the 2nd time around, vacuumed it really well, made sure it was holding good vacuum, then opening the system up to add the oil and then vacuuming it down again. That way any residual brake clean shouldn’t contaminate the oil.
  3. The 2nd time around I went ahead and bought the can of expensive flush from O’Reilly’s. Yeah, it was pricey. But considering the money and hassle of going through the system twice… it was well worth it. I’ll also say that it smelled just like some stuff I’ve had experience with for cleaning refinery heat exchangers, and that stuff just flat out *works*. When I first smelled it I said to myself “Oh yeah, *this* is the stuff!” For getting that old oil flushed out, I think it will work a lot better than brake clean. And when I started flush the evaporator with it, I got more of that old green dye out – I thought the brake clean got it all, but apparently not. To me the expensive flush obviously worked better.
 
Regarding the sealing washers needed to allow the stock hose block to mate up – I saw it noted in a thread somewhere on here that we really need the black sealing washer. The compressor instructions said to use a black washer, but that particular sealing washer was not included with the new compressor. It came with 3 – a yellow, a green, and a red. Putting the yellow and green into the back of the compressor, it looked like they would work, so that is what I used. Once in the car and tightened down though, it looks like the hose block is cocked a little, just barely. Seems to seal fine – it held vacuum and it’s held pressure, no problem. But I wonder if the fit wouldn’t be better with that black sealing washer.
 
Charging the system with refrigerant – at first I was going to just go off pressures. Low pressure = low temperature, and at first I was thinking that would be enough to ensure max cooling. But then I had a change of heart. Really we don’t care about the pressures, what we *really* care about is the air temperature coming out the vents. You might have a really low suction pressure and really cold refrigerant going into the evaporator, but if there isn’t enough of it, the air isn’t going to get cold. The higher the pressure the higher the flow is, although the higher the pressure the higher the temperature is. There is an optimum combination of flow and temperature that gives maximum cooling to the air. I don’t think you can read that combination off a temperature/pressure table. What I did was put the a/c on Normal (so it is pulling in hot outside air instead of cooler air from inside the car) and max fan speed. A digital thermometer in the center vent to read the temperature. Car at idle (though if I was doing it again I would have set the engine speed a little higher, maybe 1200 rpm or so). Suction pressure at about 35 psig. Then I started adding refrigerant a little at a time, waiting and letting the system settle out, and watching the thermometer. Added some and the air got colder. Added some more and it got colder still. I kept on adding, waiting, watching the air temp. Suction pressure was up in the low 40’s somewhere when adding more did not result in colder air. I let a little back out at that point, and ensured the temperature did not get any better, and then called it done. I (hopefully) found the optimum.

Final results:

95° outside, idle (stopped at a long light), Max A/C, fan speed 3 = 50° air from vent

95° outside, off-idle, Max A/C, fan speed 3 = 44° air from vent

95° outside, 30 mph, Max A/C, fan speed 3 = 38° air from vent

80° outside, 65 mph, Max A/C, fan speed high = 37° air from vent

80° outside, 65 mph, Max A/C, fan speed 2 = 32° air from vent

Hope all that helps somebody!
 
Great write up! Thank you. Although I would love to have a/c come out that cold, I don't know if I would have done all you did. I guess I am getting lazy. lol.
 
Can we get a link to the "expensive" orielly flush? Did you use a gallon? Other size?

Also which pag oil? Pag150? W/ice32?

Sent from my HTC PH39100 using Tapatalk
 
Last edited:
Thanks for the kind words guys, I was hoping someone would find this useful. And after 6 years or so with no a/c, it is really nice to be comfy in the car when it is blazing hot outside! It was almost uncomfortably cold when I drove it a few nights ago and it was a bit cooler outside.

Flush was this stuff:
http://www.oreillyauto.com/site/c/d...oap?ck=Search_N1785_-1_440&pt=N1785&ppt=C0050
It's a spray can with a hose. I put the hose tip on the outlet of the evaporator, sprayed some in till it started to come out the evap inlet, let it soak a while, blew it out with my compressor, and then repeated.

The oil I used was the PAG 150 stuff with the ICE32:
http://www.oreillyauto.com/site/c/detail/INT0/GPH6.oap?ck=Search_gph6_-1_440&keyword=gph6
I can't really say if the ICE32 does anything or not, since I don't have any before/after results, it might just be a marketing thing. But it sounds good :) I used PAG 150 oil because that is what was recommended for the compressor.

Compressor (both times) was from the same place I got the condenser:
http://www.ackits.com/comp-r4-5in-pv6-12v-metric-2965?search=20-10434
It was the brand new one, not a reman. The first compressor I got had a "made in Korea" sticker on it. The second one did not have any identifying stickers, though of course it looked essentially the same.

BTW, I'd like to plug these guys (ackits.com) - they really did me right. When the compressor died after a week they sent me a new one, with a new dryer and new orifice tube, no charge and no hassle at all. I thought I was going to have to at least argue my case, but nope - I told them what it was doing and they sent out new parts right away. it could not have gone any better than it did. I was extremely pleased with the way they treated me.

Oh yeah, one last piece of advice - make absolutely sure the fan is working when the a/c comes on! An initial misstep of mine... "I only put in one can. Why is the pressure so dang high???" LOL. I had to puzzle over that one for a bit. Amazing how fast the pressures will come down once the fan is plugged in and running.

Another item - I had this old fan shroud sealing kit that I had never got around to installing. It was from David Chase I think, Silver 6 products. I bought it unused from someone else several years ago. It's a rubber piece that goes around and seals the gap between the fan shroud and the radiator. Since I was doing everything else I decided to put this on, finally, and I swear it has made the car run a little cooler. No definitive data, but it sure *seems* like it is cooler.

I did notice that I can feel hot air being blown out towards the front of the car from underneath the radiator/condenser. Anyone got an idea of the root cause of that? It seems less than optimal.
 
Air has to go somewhere after it comes through the radiator and shroud. Front must be the easiest route. Probably goes under the car when the car is moving.

Sent from my HTC PH39100 using Tapatalk
 
Great write up. I haven't had ac in mine since I've owned it. It sure would make it more pleasant to drive in the Houston heat and humidity.

If you get bored and want to do this again, let me know!!!



Sent from my iPhone using Tapatalk
 
hey Dan - sure, I'd be happy to help you get your a/c going again. Having done it once I feel confident I could do it faster the 2nd time around :) My schedule is the only bad thing at the moment. But spring time I'm sure we could find the time to help get you ready for next summer. You still live over there in Northpoint?
 
One thing I forgot to mention was vacuum pumps. I looked around and it seems like there are vac pumps for sale at lots of places, and the selection was confusing at first. Lots of different brands out there. And yet, once I really started looking at them and comparing... despite the different brands... they look exactly the same (excepting the sticker), and they all have the exact same performance specs. Think perhaps they are all sourced from the same place? :) Go search for vacuum pumps at www.tooltopia.com and you will see what I mean. The only real difference is the price. So I bought this one (2.6 cfm single stage #4015):
http://www.es-refrigerants.com/products/w/id/393/t/pittstop-pro-series-vacuum-pump/details.asp
At that price I just bought it and didn't look back.
 
Thank you, these cars are so old and the AC is just not what they were 20 years ago ,and face it BLACK is hot inside.
My car is blowing in the low 50s this year and I know it time for some love
This should be a sticky
Ill figure how to save this on my desk top
 
JDEstill said:
hey Dan - sure, I'd be happy to help you get your a/c going again. Having done it once I feel confident I could do it faster the 2nd time around :) My schedule is the only bad thing at the moment. But spring time I'm sure we could find the time to help get you ready for next summer. You still live over there in Northpoint?
Click to expand...

Thank you for the offer, John. I'm not quite ready to resume spending on the car just yet. I need business to recover first. I'm planning to focus on installing things that I either already have, or things that are a true NEED. Hopefully by spring I can do some of the extra things I've been wanting to like the A/C. I guarantee that I'll be at least using this thread for reference. I have NO CLUE when it comes to refrigeration, so my plan was just to pay someone else to do it. Who knows, maybe I can grow a pair and tackle this myself (or with a little help) and actually learn something about it.

I've moved North a little from before; we're up in Magnolia now (lots more room and lots of garage space), but the move has really put a damper on the pocketbook for the short-term. Not to mention extra-curricular stuff with the kids consuming time.
 
87-WE2 said:
Thank you for the offer, John. I'm not quite ready to resume spending on the car just yet. I need business to recover first. I'm planning to focus on installing things that I either already have, or things that are a true NEED. Hopefully by spring I can do some of the extra things I've been wanting to like the A/C. I guarantee that I'll be at least using this thread for reference. I have NO CLUE when it comes to refrigeration, so my plan was just to pay someone else to do it. Who knows, maybe I can grow a pair and tackle this myself (or with a little help) and actually learn something about it.

I've moved North a little from before; we're up in Magnolia now (lots more room and lots of garage space), but the move has really put a damper on the pocketbook for the short-term. Not to mention extra-curricular stuff with the kids consuming time.
Click to expand...

If you want to tackle it let me know, I'd be happy to help. Magnolia ain't that far away. :) I hear ya on the kids... you'll probably be wanting the a/c right when little league is going full blast LOL
 
The EnviroSafe freon you used is the coldest stuff I have found.I have used it for 11 or 12 years with no problems at all.I used it on a few of my friends TR'S and a Cutlass and they all said their air had never been that cold.I keep several cases on hand just for that purpose.Nice write up!!!!:cool:
 
Yeah, it seems to be working well. I wonder if I should have used a different orifice tube with it. You got any experience with how different OT's behave with this stuff? It's labeled as R134a replacement, so maybe I should have used the blue OT.

For anyone that wants to order this stuff, the price per can looks really cheap, like $6, but they tack on a $23 hazmat fee if I remember right, no matter how much you buy. That makes 1 can really expensive, but if you buy several cans the price per can comes down quickly. I bought 6 and used about 2 and a half. Those 6 cans, with shipping plus the hazmat fee, ended up costing about $13-14/can when it was all said and done.
 
When I can get the 152a for less than $5/10oz can and it has closer characteristics to r12 , I think it a no brainer to go with it. I will go with red ford orifice tube and a new drier. I'm Hoping to do mine this weekend. If I can get those parts and some orings local. Other wise I will have to wait til the parts get to me. My Chinese gauges n vacuum pump came last week. I'm hoping mine turns out as good as yours.

Sent from my HTC PH39100 using Tapatalk
 
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