Engine Freon not entering system

sav22rem22

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Feb 6, 2020
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So since it’s about to get unreasonably hot here in the south I figured I’d try and get my ac working this summer on my 89 GT. I went out today to get some retrofit adapters only to find out my car already has them on. I also picked up a can of ez chill r134a with the gauge built into the line. I don’t know much about the history of my car and especially with the ac system. It didn’t work when I got it and I never looked into it until now. So I turned the car on and hooked the line up to the low pressure fitting and tried to start filling it up.

I noticed nothing was really happening and the compressor wasn’t turning on at all so I found a forum somewhere on here explaining that I could jump the low pressure connector to force the compressor on. I jumped it and voila it turned on. So I then tried to start filling again. I didn’t want to keep the compressor on for long as I didn’t know the condition or amount of oil in the system. It seemed as if nothing was coming out of the can even though the gauge was moving. The system measured 0 PSI and when I pushed the button to fill it up it shot up as if it was filling but when I let back off to measure it dropped back to 0. I also noticed that after about 15 minutes of trying this the can wasn’t getting any lighter and none of the r134a seemed to even be going into the car. The ac also wasn’t blowing any colder.

What could cause nothing to come out of the can like that? I know I’m probably going to get the lecture on how putting r134a into an r12 system is bad and won’t last but I don’t have 600-700 extra bucks lying around to purchase an out of stock conversion kit. What steps should I take next to at least get the AC working temporarily so the car is even drivable this summer?
 
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7991LXnSHO

wanna catch the space herp
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First, I hope someone already did a decent conversion for you. I was surprised wen my 91 needed a leak fixed and refilled that it had already been converted. It works as well as the dealer R-12 system did on an earlier Mustang.
 

nickyb

WAIT,you now have a pair?
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You need to introduce freon into a vacuum. Get a a/c vacuum pump and pull a vacuum, see if the system holds 28 inches of vac. For at least one hour ,then put freon in.
 

7991LXnSHO

wanna catch the space herp
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You need to introduce freon into a vacuum. Get a a/c vacuum pump and pull a vacuum, see if the system holds 28 inches of vac. For at least one hour ,then put freon in.
An old Kirby should be at least 28” of vacuum. Now how does the AC system hold it without pulling the hood?
:D
678E7505-24A5-47C4-8289-E86BF405D137.jpeg
 

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Mustang5L5

Put lubricant all over the balls
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You really need to pull a vacuum on the system. Under 500microns and then it should hold for 24 hours or better. Having to continuously dump cans into the system also means there is a leak and it should be replaced.

With a totally evacuated system under vacuum, you should add about 32 ounces of R134a. You may have to jump the pressure switch on the accumulator to help get the pump going. You'll also want a 2-guage system to watch both the high side and low side pressure. The low side will likely drop below 20psi which will help pull in 134a from the can since it's internal pressure will be higher.

Unfortunately AC work can get complicated and expensive.
 
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sav22rem22

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Feb 6, 2020
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You really need to pull a vacuum on the system. Under 500microns and then it should hold for 24 hours or better. Having to continuously dump cans into the system also means there is a leak and it should be replaced.

With a totally evacuated system under vacuum, you should add about 32 ounces of R134a. You may have to jump the pressure switch on the accumulator to help get the pump going. You'll also want a 2-guage system to watch both the high side and low side pressure. The low side will likely drop below 20psi which will help pull in 134a from the can since it's internal pressure will be higher.

Unfortunately AC work can get complicated and expensive.
Well I’m not ashamed to admit that unfortunately doing this myself is indeed a bit over my head. I’ll be taking the car to a reputable shop and having them put vacuum on it. What oil should I use for the system if I’m not sure what’s already been done in the past?
 

sav22rem22

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Feb 6, 2020
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Well an update to this thread is that the low pressure switch was bad and the system was completely out of Freon. As for why I couldn’t get any Freon to enter the system I have no idea but I got a shop to charge it up for me and I now have AC $131 later (yikes) and that’s why I hate going to shops. The AC is decently cold and hopefully it’ll last me until I can do a whole conversion kit. The car really hates AC though it strains the weak factory alternator so bad that I can feel the car almost losing power going down the road. At least I have cold ish AC for a while
 
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7991LXnSHO

wanna catch the space herp
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$131 is a pretty cheap trip to a shop for AC, especially as they are required to (or are supposed to) find and stop the leak before filling it.
 

sav22rem22

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$131 is a pretty cheap trip to a shop for AC, especially as they are required to (or are supposed to) find and stop the leak before filling it.
Hmm I didn’t know that. After I thought about it a little bit I felt a little better about the price considering all the environmental fees and stuff shops go through. Now to do a proper base idle reset with the compressor actually kicking on so the car stops throwing a huge fit