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08-22-2015, 10:12 PM #1
83 Air Conditioning Repair - With Results & Numbers
I've had my 83 since 2001, it has 252,000 km on it now, and I don't think I will ever sell it.
The A/C wasn’t working for 8 years due to a leak. A re-charge had been done 8 years ago at the shop, but it leaked out very shortly thereafter. I had seen bubbling from around the sight glass of the receiver/drier, so I knew where the leak was. If you aren't sure, there is a UV dye that can be added to the system to identify the source of the leak.
This summer I found the system was still holding about 5 or 6 psi, so no moisture should have entered the system and corroded the interior parts. That gave me hope that the system would be in good shape. So I bought the tools, parts and supplies to get the A/C system working again, doing the work myself this time.
I made this post to outline my results, and if there are any AC experts reading this, I’d be curious to hear from them regarding optimal system pressures.
I’ve already read thru the forums (e.g. Jim’s MK2 A/C FAQ)
I vacuumed the system from 5 psi down to 0 psi. Opened the system and replaced the receiver/drier.
Then I vacuumed the system down to -27 psi to check for leaks.
Once no leaks were detected I added approx 9 oz. of Duracool refrigerant (1.5 cans). The amount I added was based on the system pressure I thought I should be targeting, 20-30 psi low & 200-300 psi high.
I stopped filling with refrigerant when the low side reached 30 psi. However the high side was only at 170 psi. I had to stop there so as not to exceed low-side pressure, but I was hoping for a little higher pressure.
The previous re-charge had added 4 oz. of compressor oil, so I didn’t add any more oil (since I assue it’s still in there).
Afterwards I measured the air temperature at 9 degrees Celsius (48 Fahrenheit), pretty good, could be better I guess. I heard that 40 Fahrenheit would be very good.
Can anyone confirm what good AC system pressures would be for the Supra ?
- Low-side 28-30 psi
- High-side 160-170 psi
- Air temp: 9 degrees Celsius (48 Fahrenheit)
- New receiver/drier part ($15)
- Manifold gauge set ($50)
- Vacuum pump (borrowed from work, free)
- 2 cans of Duracool (r12 replacement) refrigerant ($26)
- Refrigerant can hose to adapt to the manifold gauge set ($30)
Thanks for your interest,
Last edited by SupraMoto; 11-06-2016 at 03:25 PM.
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08-22-2015, 10:25 PM #2
150-180 and more,depending on the air temps.
Gotta get AIR across the condenser.
HEADER panel will help but the wimpy condenser fan needs to be replaced with a larger one.
10-12" is great! I use a De Rail 10"Use the stock bracket and be sure that the condenser is not clogged with leaves.
Pay attention to the out put temps. 50F* is really good.R-12 works the best.
Adjust the system pressure as needed.
Common leak points are at the drivers side,where it feeds the condenser.
Just curl your finger around both lines at the fitting. Gotta dirty finger? Tighten those lines,carefully.
Mine went toast when I overcharged it.Burned the A/C clutch to hell.
30 pounds of scrap metal.
08-22-2015, 10:34 PM #3
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08-22-2015, 10:48 PM #4
No, not for Seattle weather and I'm a skinny dude.
FAT boys need A/C.
The entire system is full of crap when the dessicant bag blew. GREY poop in the sight window.
It's gonna be tossed. Arizona or Nevada? Oh yeah,it would be repaired!
$1,000 to do it correctly.
The heater works so I'm golden.
See my post on making it blow more air.
I put a 12V. blower inside my lower duct.
Keeps the family jewels cooler.
08-23-2015, 01:23 AM #5
Yeah, understandable. I wouldnt have invested that much in my AC either, my repair cost me just $121.
08-23-2015, 11:55 PM #6
Nice little write up, and your fill numbers are in line with what i've ended up with. A pic of where the fittings are and a link to a basic fill video would make this almost completely dummy proof. Add in a table with pressures based on ambient temps and you'd be icing the cake.
Off topic, but what're the toggle switches you've got hooked up in the trip computer spot for?Hidden Content 86 parts car maybe some day race car? 3x cars, 36x brake caliper pistons.
"You need to update your signature Gamble" - Dave
08-24-2015, 12:30 AM #7
Thanks, and for the suggestions. I'll add some extra information for the sake of others doing the same repair.
The toggle switches activate the afterburner, it really kicks hard when activated !
........Actually, one switch controls the rear defrost since it doesn't stay on by itself when pressing the stock momentary switch down, it would otherwise have to be held down with a finger to work.
The 2nd switch turns on/off the windshield wiper power, because the hide-away function stopped working and they flap continuously trying to tuck away otherwise.
08-27-2015, 02:19 AM #8
- Join Date
- Aug 2011
- Arlington, WA
I deleted everything I previously wrote after doing some research. System pressures are relative to ambient and to the specific refrigerant. The critical variable is that the evaporator must be kept from freezing so typical evaporator temps are regulated to 35 - 40 degrees F with vent temps 40 - 50 depending on ambient after the system has run a while. High side pressures are whatever is required to get the proper heat transfer at the condenser so higher ambient temps mean higher high side pressures. It's important that your system have the proper amount of refrigerant charge and oil and low side pressures are not good indicators of this. There's much more to this so do the research and/or consult an expert.
While I have recharged my own systems a couple of times, I've always had an expert on call for advice. This is not something you should guess on. Consult a real A/C expert to verify proper operation of your system.
Last edited by ray85p; 08-27-2015 at 04:20 AM.
08-27-2015, 11:42 AM #9
Thanks for your info & advice. So my vent temperature is on the high side of the 40 - 50 you mentioned.
I had done 2 rounds of adding refrigerant, after the first round I drove it for a week to check operation and temperature, then I re-checked pressure and added a bit more refrigerant but there was little change.
I had done the pressure test in my garage with the car idling. Perhaps if it was out in the heat the high side pressure would be higher, and if the car was running at higher RPMs the vent temperature may have been colder.
My main concerns was that the system may be overcharged leading to damage, or that I should put more compressor oil (PAG oil) in the system. I know there are tests to determine oil content, perhaps I should check it just to be safe.
09-05-2016, 12:52 PM #10
Great write up !!Regards,
'86 Supra MA67
Brullen 2.5" Exhaust, HKS Fly w/7MGE clutch,ST Springs, RC Intake & TB, 2.8GT & XX emblems, Factory Add on Rear Shoulder belts, Pioneer DEH-P2000 AM/FM/CD w/CDS-P5000 CD Player, Compomotive CXNs 8x16
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