reinstall of AC after a long time without it- best practices for a refresh?
07-14-17, 08:23 PM
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reinstall of AC after a long time without it- best practices for a refresh?
I've run my 93FD as a track day car pretty much since I bought it used with some front end damage around 96. I built it up back then without AC, big intercooler and no PS. Now that I've moved down to Georgia I'd like to reinstall the AC (I have all the old parts, but have some doubts about if the compressor works BC the AC didn't work when I got the car). Of course the world of AC tech has moved on and with the little reading that I've done looks like I might want a hydrocarbon refrigerant like es12a and maybe a more modern compressor. Looks like a lot of aftermarket systems use a Sanden 7176, but I've heard there is a Toyota unit that is pretty much a bolt in. Because I have a big IC and a slightly repositioned radiator I may need to redo some lines to mount the oem condenser & I'll need a new (generic?)drier of course. What components would be best to use? I like the car without PS and can't remember if using the stock AC mounting setup necessitates having the PS pump in place...so a different compressor might not be much extra work over an OEM one, and might be cheaper especially if I have to redo lines and the manifold where it connects. What should I do?
Last edited by tom.jelly; 07-14-17 at 08:38 PM.
07-14-17, 09:52 PM
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It doesn't get to the track as I don't have time anymore, but I run both fans manually on full speed when it comes up to temp and temps have never been an issue. It won't ever be in traffic either, just for fun toy duty now.
07-15-17, 07:54 AM
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First thing, do you have the MANA or Nippondenso AC system? That's a big one. The Nippondenso have easy-to-get receiver/dryers, where the MANA is not available.
9 times out of 10, a non-working AC is from all the refrigerant being gone from the system. That's most likely what happened originally. You will probably want to go over all the parts with a fine tooth comb looking for leaks, it's not uncommon to have the aluminum AC lines have holes due to something rubbing against it.
Most likely the compressor is probably fine.
Here's what I would do -
- Get all new O-rings for the system. You can get metric o-ring kits that should cover the whole system.
- Get a new receiver/dryer. Hopefully you have the ND system, you can pick those up at most any parts store. If not you'll need a custom one made. This is the filter for the system and should be replaced any time the system is open.
- Get some AC line flush. Look around online, there's places that sell AC tools and parts that have stuff to "blow out" AC lines. You want the inside of those lines spotless and clean - no dirt, dust, bugs, etc. Take your time with this.
For refrigerant, I'm a big fan of using Dust-Off, there's a massive thread in the 2nd Generation section all about this. It's very cheap, easily available, and will cool the car as good as the old R-12 did. That thread also has recommendations for what oil to use in the system and how much oil.
If you're doing everything yourself you'll need a GOOD vacuum pump and a set of manifold gauges. The vacuum pump can be rented from some parts stores, not sure on the manifold.
Dale
9 times out of 10, a non-working AC is from all the refrigerant being gone from the system. That's most likely what happened originally. You will probably want to go over all the parts with a fine tooth comb looking for leaks, it's not uncommon to have the aluminum AC lines have holes due to something rubbing against it.
Most likely the compressor is probably fine.
Here's what I would do -
- Get all new O-rings for the system. You can get metric o-ring kits that should cover the whole system.
- Get a new receiver/dryer. Hopefully you have the ND system, you can pick those up at most any parts store. If not you'll need a custom one made. This is the filter for the system and should be replaced any time the system is open.
- Get some AC line flush. Look around online, there's places that sell AC tools and parts that have stuff to "blow out" AC lines. You want the inside of those lines spotless and clean - no dirt, dust, bugs, etc. Take your time with this.
For refrigerant, I'm a big fan of using Dust-Off, there's a massive thread in the 2nd Generation section all about this. It's very cheap, easily available, and will cool the car as good as the old R-12 did. That thread also has recommendations for what oil to use in the system and how much oil.
If you're doing everything yourself you'll need a GOOD vacuum pump and a set of manifold gauges. The vacuum pump can be rented from some parts stores, not sure on the manifold.
Dale
07-15-17, 08:46 AM
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Pretty sure its a nippon system - bare aluminum drier (nippon =natural aluminum rather than black painted drier= MANA, right?), assuming that how to tell). It was 20 years ago but I THINK one of the deciding factors in removing the system is that when I originally got the car together I was unable to get cold air out of the system. I had/have a excellent vac pump, 12a manifold gauge set, pulled a vacuum (and it didn't leak down) used real 12a refrigerant and replaced all the o rings but can't remember if I replaced the drier, and I think I was not getting pressure differentials that made any sense. I do remember contemplating a 134a conversion and discounting that because I read the car didn't have barrier hoses, and drop in 12a substitutes were not really a thing yet. I just gave up and removed it, and would not (and still will not) trust any shop to work on the car. I like the 152a so I'll use that if I can.
Last edited by tom.jelly; 07-15-17 at 12:39 PM.
07-17-17, 11:09 AM
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Sounds like a good game plan. Could also be a bad expansion valve in the evaporator under the dash, and I do believe they are available. Also, you don't have to pull the dash to get the evaporator out, just the glove box.
Dale
Dale
07-17-17, 01:13 PM
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Good to know, depending on the price may just replace that as well as I imagine a flush would be more effective without that in place as long as I can figure out a way to catch the flush agent under the dash. If that's not practical I'll just skip it
t
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07-18-17, 10:45 AM
#8
I think a lot of people overthink the ac system with fancy refrigerants. R12 is obsolete and I don't like the replacements as they are difficult to get readily. The first thing you need to do is find and fix any leaks. If the system hasn't been previously serviced and has no dye, this can be difficult. Throw a small amount of charge and some dye in it so the compressor kicks on, then let it circulate. If the compressor isn't kicking on usually its a low pressure problem or an issue with the pressure switch itself. With Power FC cars or other aftermarket ecus sometimes the ac wont kick on some of the fan speeds (search power fc ac fix) If the compressor doesn't kick on you can do so by grounding its wire but make sure you have a charge and oil in the system so you don't burn it up. Only run it a few minutes. Get some yellow tinted glasses and a uv light and find/fix any leaks. When I do an ac system, I remove all the lines and flush them, then reinstall them with new orings. I like to do a new expansion valve as well. An old trick classic car guys do when they can't get an original dryer is put the dryer in the oven for 20 minutes or so. Bake it at 150-200F degrees, nothing crazy. What you are trying to do here is get the moisture to evaporate. If a new dryer is available, I prefer to replace it. Get some 134a retrofit fittings from any autoparts store. Put in a little 134a conversion oil and change the fittings. Draw the system to a vacuum for 1 to see if it holds, and 2 to pull out any excessive moisture. Vacuum the system for a minimum of half an hour, then charge to spec with 134a. The stock system takes about 1.5lbs with R12. For 134a it will be closer to 1.2 lbs. If everything is functioning properly a correct conversion will be within a degree or two of a comparable r12 system. I've built plenty of cars that went to Florida and California and the ac system was more than adequate.
07-18-17, 12:11 PM
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The only AC parts in the car are the evaporator and the lines from that to the right headlight area, everything else was removed, so there isn't anything to leak yet, though I will be pulling a vacuum for a long time after assembly. drier, compressor and some lines will be new, condenser and evaporator will be original. I don't want an r134 conversion as it will end up being the same issue as r12 eventually, unavailable or impractical, not as efficient, etc.