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A/C works so so

CyFi on Tue July 22, 2008 11:18 PM User is offline

Year: 1987
Make: Toyota
Model: Supra
Engine Size: 3.0
Refrigerant Type: R12 to ES12
Ambient Temp: 75
Pressure Low: 25runing
Pressure High: x

Before i start, here is the online AC repair manual for my car.

Click Here

Hello all, i have been quite frustrated with my air conditioning system recently. I first bought this car back almost a year ago, it had the original R12 charge from 25 or so years back. The AC worked, but hardly. Anytime it would get above 80-85 degrees outside the AC would struggle to cool the air much. Upon looking in the sight glass, it was apparent that the charge was low (bubbles while running). I had used this ES12 refrigerant in my MR2 with great results, so i figured instead of paying up to get the system charged with r12, i would switch back to the hydrocarbon refrigerant. I had found my small leak, when i removed the high side plastic cap, i could see refrigerant bubbling out slowly, so i had the r12 recovered and replaced both valve cores.

While the system was open, i replaced most of the AC seals as well just for assurance, i also replaced the receiver dryer. I closed the system back up and took it back to the ac shop and had a vacuum pulled on the system. I got the car back home and in this order, filled the system

4 oz Oil charge
6 oz Refrigerant plus dye
6 oz refrigerant plus dye

At this point my pressures seemed to be where they should be.

2000 RPM pressure ~ 25 psi low side

Idle ~ 35-38 PSI

But, i was not satisfied with my vent temperature. Sitting idle in 70-75 degree weather, my vent temp was approximately 53-55 degrees F
Driving around in the same weather, vent temp would on average be around 45-50 degrees F
Cruising at highway speed, the lowest temp i saw was 40 Degrees F

Now i understand, hydrocarbon refrigerants don't tend to do as well at idle speed, and i do have a mechanical fan which might not be pulling enough air for the refrigerant, but then again, outside temp was only 75 degrees.

After this, i had another 5 oz can of refrigerant, i thought i would add it in to see how it would affect things, to my surprise there was little to no rise in low side pressure, and pretty much no change in vent temps.

I have done a lot of reading on hydrocarbon refrigerants since and i am having a hard time figuring out what my problem could be, all i can think of is i either
-Overfilled the system
-Put too much oil
- Or some part of my AC system has gone bad.

Now, these temps would be fine with me, but i am moving to Arizona in less than a month, and i am nervous as to how my system is going to perform. I have no real way of testing how it will do in hotter weather, because i am not around any hot weather. While i have the car here i can do any modifications i need, but once i go to Arizona i wont have access to many tools or equipment. I do not mind handing it over to a qualified shop to diagnose, but my biggest fear is nobody is going to work on a system that has a hydrocarbon refrigerant in it. So i am considering getting the system evacuated, switching to 134A and seeing what happens, that way i can diagnose the system with a real set of high/low side gauges. Right now i only have a low side gauge, and high side pressure is irrelevant with ES12 anyways.

Also, my static pressure is around 80-85 PSI ~78 degrees F.

Thank you so much for your input, i have been researching like crazy and i am still a total nub to air conditioning and i am struggling to find an answer to my problems. Click Here

Edited: Wed July 23, 2008 at 5:17 AM by CyFi

94RX-7 on Wed July 23, 2008 12:19 AM User is offline

Did you charge as a liquid? If you didn't, you might have the wrong proportions of HCs in the system. 4oz of oil is a lot of oil to add to a system that presumably doesn't need much if any added to it.

CyFi on Wed July 23, 2008 12:22 AM User is offline

I shook the can and inverted the can to fill as the directions state. I was not sure how much oil to put as i have no idea how much was there before and i thought i would want to be safe rather than sorry. Compared to when the r12 was in there, the compressor runs 10 times quieter now.

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