I charged my system with freeze 12 and I got it working however it is inconsistent,it will blow cold down to 40 deg at the vent but if I give it gas, a little above idle ,the clutch cycles off and then back on and the temp shoots up to allmost 50 deg.If I jump the switch on the receiver it blows nice and cold for as long as it is jumped.I only have one of those pen type gauges ,it says im getting around 27 psi on the low side.Does the switch need to be swapped out if im running 134a or in my case freeze 12.or could it be not enough freon.
A/C question
- Thread starter rockyracoon
- Start date
The problem is either that you are still a little low on charge or the low pressure cutout switch needs adjusting. IIRC, PuteramI (Larry) posted that if you look carefully, you will find the adjustment on the switch you described jumpering. See http://forums.stangnet.com/showthread.php?t=571812&highlight=adjust. I believe that each 1/4 turn counterclockwise lowers the cutoff pressure by 1 PSI.
Ok I just took another reading but this time when I revved the car up to about 1500 RPMs,cause thats kinda where the compressor is cutting off,it seems that the PSI is going above 40 PSI, does the switch also control high PSI on the low side? do I need to adjust the switch or remove some gas (recover) from the system? im hesitant to remove some gas because as stated when idling the low side PSI is like 26-27 and supposedly that is kinda on the low end of the spectrum and I dont have any more freeze12 on hand to put back in the system.
The switch is designed to cut off when the pressure drops below the safe operating point. This is to protect the compressor from being run with no oil. As long as the pressure is above the cutoff point, the switch should be on.
Use a voltmeter or test light across the pressure sense switch to check it's operation. Use safety pins to probe each wire on the switch connector from the rear. With the switch closed (pressure OK), it should read less than 1 volt between the two safety pins. If the switch opens (pressure low), the voltmeter will read 12 volts or more.
Use a voltmeter or test light across the pressure sense switch to check it's operation. Use safety pins to probe each wire on the switch connector from the rear. With the switch closed (pressure OK), it should read less than 1 volt between the two safety pins. If the switch opens (pressure low), the voltmeter will read 12 volts or more.
Ok I got a better gauge and I have 27 psi at idle then when I give it some gas it goes gradually down to 16 psi,I adjusted the switch to 15psi and the system will now run continuously however I assume that 15psi is too low for the switch to be set at.does this sound like there is some kinda problem or simply a little low on refrigerant? beraing in mind that the A/C blows ice cold at the vents with the switch adjusted or jumped.Would it be ok to top it off with 134a since the freeze 12 is like a mix.The reason I ask is that I ran out of freeze 12 and there are no local sources for it.
Short version of the answer: No.rockyracoon said:
Here's why:
As previously posted, Freeze 12 is a blend of two refrigerants. The ratio of one refrigerant to the other is what makes it work. Putting more R134a in would lower the ability of the refrigerant blend to carry oil and lubricate the compressor. Now you know why the advice was given to stay away from Freeze 12. A proper R134a conversion would have kept you from having this problem.
backfocus
Member
How much freon have you already put into the system. Using Freeze 12 you will need less than the normal 40oz of R-12, but only 10% less. So I would initially use 36oz, but with that said you must account for loss minimum loss when replacing cans. So 3, 12oz cans will get you close, but probably not enough.
From the your description you described, it sounds like you are still a little low on charge. What is the condenser temp and vent temp, with engine is idling? Knowing those two numbers will help in knowing the correct pressure for the time of year.
From the your description you described, it sounds like you are still a little low on charge. What is the condenser temp and vent temp, with engine is idling? Knowing those two numbers will help in knowing the correct pressure for the time of year.
backfocus
Member
Put the thermometer about an inch in front of the conderser while running at idle, windows should also be up or close to it. Operate the AC and fan at Max to start for 3 or 4 minutes. Now turn the Ac and fan to low, wait a few more minutes, you will see pressures start to steady. This is when you take your temp readings, both at condenser and at the vent. The vent temp should slowly go down. You are looking for a difference of 30 to 40 degrees between the two temps. Also the condensor temp will help determine the pressure. You should be able to find a pressure/temp chart for Freeze 12 on there website.
I would shoot for 32 on the low, but add a few more onces slowly. Put in a little and let the pressure steady again.
I will try to find a P/T chart for freeze 12 if I do I will post it.
Do you have a High side reading?
I would shoot for 32 on the low, but add a few more onces slowly. Put in a little and let the pressure steady again.
I will try to find a P/T chart for freeze 12 if I do I will post it.
Do you have a High side reading?
Running down A/C cooling problems is impossible without a set of A/C manifold gauges. All this talk about adding a few ounces here or subtracting a few ounces there is worthless without a set of gauges. In order to properly diagnose ANY A/C problem (Automotive or HVAC), you need to start from the beginning with some baseline information:
1) Outside Ambient Temp.
2) High Side Pressure Reading with Engine at idle
3) Low Side Pressure Reading with Engine at idle
4) Interior Vent Temp with Engine at idle (A/C set at low)
5) High Side Pressure Reading with Engine at 1,500 RPM
6) Low Side Pressure Reading with Engine at 1,500 RPM
7) Interior Vent Temp with Engine at idle (A/C set at low)
Do you have access to an R134a manifold gauge set? If so, post answers to the aforementioned questions and I can help chase down your cooling problem.
1) Outside Ambient Temp.
2) High Side Pressure Reading with Engine at idle
3) Low Side Pressure Reading with Engine at idle
4) Interior Vent Temp with Engine at idle (A/C set at low)
5) High Side Pressure Reading with Engine at 1,500 RPM
6) Low Side Pressure Reading with Engine at 1,500 RPM
7) Interior Vent Temp with Engine at idle (A/C set at low)
Do you have access to an R134a manifold gauge set? If so, post answers to the aforementioned questions and I can help chase down your cooling problem.
backfocus
Member
I am was under the impression that he had a gauge set. I have been doing AC repair for 15 years now. Did it professionally for 5 and now as a hobby.
You can't charge a system full bore at once and expect it to work to its potential. All systems, even on like cars are an once or 1/2 an once one way or the other. Especially since he is using a freon not originally designed for the system.
backfocus said:
I agree. But adding any amount of refridgerent (whether it's 4oz. or 40oz.), to a clogged or partially clogged A/C system is useless. You will NEVER achieve the proper cooling capabilities if the system is clogged. In order to determine whether the system is clogged (usually at the O-tube) it's necessary to have the baseline Hi / Lo pressures.
The other thing we need to know is whether the system was prepped properly before the Freeze-12 was added. Was the accumulator replaced? Were the O-rings replaced with green rings? Was the system flushed with mineral spirits (excluding the compressor)? Was a vacuum pulled for at least 45mins to absorb any remaining moisture? Background information on how the conversion was preformed is crucial to diagnosing the cooling issue.
backfocus
Member
He has been working on this for a few weeks now. So I read his other post about how he setup the system.
new drier,vac pulled on sys for at least 3 hours,prior to evac, sys was flushed and psi tested with N2.syswas not flushed with solvent, added 1oz of compatable oil,only 2 o rings replaced were green the smaller I believe were just plain black ones,reason being is I had a kit from autozone with an assortment of A/C rings and they were not in the mix, then I went to the ford dealer and he could not match em up,so I found 2 that I had at home that were black and were the correct size.the guy at the dealer said it didnt matter that much,that the black just wouldnt last as long.and im not using a manifold set just a gauge on the low side.Im gonna go out nd get a set.I have a raincheck for one over at harborfreight just waitin for them to come in.
rockyracoon said:
Okay. That's some good background information. Post your pressure readings when you get the A/C manifold. Couple of follow-up questions. When you say the system was flushed, but not flushed with solvent, what product was used to flush the old mineral oil? Generally most guys us brake cleaner or mineral spirts. More importantly, what type of oil did you use with the Freeze 12 (PAG, Ester, or Mineral)? You should only be using Mineral Oil with Freeze-12. You also mentioned that you only added "1oz of compatable oil". R134a conversions on Fox Mustangs require a total oil charge of 8oz. I generally add 4 ounces to the compressor (and turn it by hand 8-10 rotations), 2 ounces to the condenser, and another 2 ounces into the evaporator. I wouldn't recommend running the compressor with only 1oz. of oil in the system.
Okay. At this point, I wouldn't do anything else until you establish your pressure readings. Once we determine the system is clog free, we can figure out if adding more oil or more refridgerent is necessary.
I'm guessing I can't convince you to start over by recovering the existing Freeze-12 and flushing the system with mineral spirits? I just don't like the idea of leaving old mineral oil in the system. The other thing is that you really have no idea how much "actual" oil is in the system. I'm sure the nitrogen flushed out 80% of the old mineral oil, but that still leaves about 20% of the system coated in old mineral oil. It may not be a big deal depending on the "condition" of the oil, but I wouldn't want to have to start over again if the system performance continued to deteriorate. Just food for thought.
I'm guessing I can't convince you to start over by recovering the existing Freeze-12 and flushing the system with mineral spirits? I just don't like the idea of leaving old mineral oil in the system. The other thing is that you really have no idea how much "actual" oil is in the system. I'm sure the nitrogen flushed out 80% of the old mineral oil, but that still leaves about 20% of the system coated in old mineral oil. It may not be a big deal depending on the "condition" of the oil, but I wouldn't want to have to start over again if the system performance continued to deteriorate. Just food for thought.
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