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Curious who has had good results on the conversion process? I just finished a conversion on my Grand National and am not that excited. New seals all around, variable orifice tube, cleaned out all the lines and had to remove the stock high side schrader valve to use the new 134a fitting that I ordered. Stock system uses 52oz of R12...conversion says to use 40oz of R134a. New accumulator...added the appropriate amount of Ester oil. Vacuumed it down several times to make sure there aren't any leaks. Once charged up...with 80 degree ambient temps I'm getting about 48-50 at the vents with varied driving around town and on the freeway. Temp climbs to about 55 on the freeway. I was expecting temps in the upper 30's. Anyone got any ideas?
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Did you change the condensor? What are your pressures showing?"It's another burrito, it's a cold Lone Star in my hand!" -
30* +/- difference from ambient temp is what a proper cooling system should be at. So looks to be operating properly.Comment
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R 12 to 134 Change
I did that change on a 93 Foxbody. Worked great after I changed the pressure cut off switch to one that was from a 134 car. I dont know how a GM system works, but I bet there is a swich to shut off the compressor in a low charge condition. I get about 40 degrees at the center vent after it cools down some. My car is black, and that hurts the AC. I can get about 35 degrees if I am in the shop out of the sun.Comment
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the pressure switch is adjustable on most of the fox cars, slot in between the two prongs inside the connector.Originally posted by FastFox View Post"If I asked people what they wanted, they would have said faster horses." - Henry FordComment
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I would get rid of the variable orifice tube and go back to the stock white one. You may need to adjust the low pressure switch if the system is cycling a lot on the highway, make gradual adjustments, a 1\8-1\4 turn out at a time. I would have used Pag150 over the ester oil, I would also recommend flushed the lines, condenser, and evaporator with an approved a\c flush, I generally use the Tech Select from Napa, a couple quarts would do you. You need to purge the condenser and evaporator for 30-45 minutes to effectively remove the flush. DO NOT use carb cleaner, brake cleaner, etc to flush with, it leaves a residue and is not good for the system.
As far as system fill goes, you need as close to the factory fill as possible. The way r134 carries oil through the system when operating requires it be full. If the system is low by as little as 10% of system charge, it reduces oil movement by 40-50%. By function, R134 only carries 50% of the oil through the system at any given time.
I would vacuum for a minimum of an hour and half.
There is more to it than what's above, but that covers the key points.
If you'd like you can call me @ 903-564-3377w or 903-819-6430c, my name is DavidComment
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Fox AC Pressure switch
I knew it could be, but with the cost so low, I just got a new one. Fox AC's were marginal at best, especially in a black car.Originally posted by Baron Von Crowder View PostComment
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We need high and low side readings plus the ambient temp at the time. Your high side should be roughly 2.5 times ambient low side 30 40 ishComment
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Changed the leaking high side schrader valve and pulled a long vacuum. It held solid for over almost 3 hours. Charged it up when it was about 90 degrees with the amount specified of R134a (40oz). Temp at the vent got down to about 55-57 at idle. High side was guage was showing around 240-245, low side was about 40ish. Drove around for about an hour and temps were hovering around 55-60 at the vent. Got home today after car sat for 24 hours...drove it...yeah...could barely get the temp to 75...its STILL leaking. Never had this issue with Freeze 12. And Freeze 12 was about 10 degrees colder with better pressure readings. Im about ready to give up on this conversion and buy some Freeze 12/R12 on craigslist or some ES12A (propane basically) and go back to what I know works. FUCK THE EPAOriginally posted by QIK46 View PostComment
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I've had issues with the high side conversion fittings leaking before. In my experience the oring in the conversion fitting that seals it to the factory service port is too thick, when you tighten the fitting down, it pushes the excess out into the void where the schrader valve opens into. When you remove your coupler it keeps the valve from fully seating closed.
Like I said before I'd get away from the variable orifice tube and go back to a fixed. I wasn't happy with the performance of the variable in my 82 regal when I did the conversion back in 04. If you want something different go to a Red or Orange tube, the orifice is just a little smaller and will help keep the low side pressure down some. We used to drop the size in Fords on conversions to help with cooling. I believe I've got a Red in mine now.
Also like I said before, you'll need at least 90% of the factory fill to ensure proper lubrication for the compressor. If you have access to a surface temperature thermometer (an infrared WILL NOT WORK FOR THIS) you can measure the inlet and outlet of the evaporator. You want the temperature difference to be within 5 degrees of each other. This ensures the evaporator is flooded or filled with liquid refrigerant which is what is required for the system to function properly and to carry oil correctly. If it's not full then the oil falls out of suspension and you will end up with an evaporator full of oil and a compressor dry.
One issue you will run into is that the condenser is not efficient for R134a, that is why they recommend the 80% fill thing. It's not because the system needs less refrigerant when converted, it's because they didn't know how to effectively control the pressures. Same reason they would add auxiliary fans.
It's @ 94 in the shade right now and this is my center vent temp.
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Heck I just threw on the conversion fittings on my integra, filled it with 134 and been working perfect for 3 summers with no leaks now. Blows pretty cold.Comment
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