A/C questions - JeepForum.com

 
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post #1 of 6 Old 03-20-2017, 03:40 PM Thread Starter
TheMatrix
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1998 TJ Wrangler 
 
Join Date: Feb 2008
Location: New Jersey
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A/C questions

I recently replaced my leaky evaporator, and while doing so also checked the orifice screen while the system was open (since the previous owner blew out the old one and there was shrapnel floating around). When I pulled it out, the orifice came out in two pieces, including a little spring. I was prepared to buy a new one, but no one had any in stock, and the two pieces seemed to pop back together. So I looked at some photos online, got the spring in the right place, and it all seemed to jive, so I figured it'd be worth a try.

I've never done A/C work in the winter, nor have a made note of how frequently the compressor cycles in cold weather. After I put everything back together, evacuated the system, it held a vacuum, and put 2 12 oz cans in (I believe my TJ's capacity is ~20oz) it was still constantly cycling on for 10 seconds, off for 5. On the last can I messed up and lost a bit, so I thought maybe I didn't have enough. So I put a third (!) can in, and it still acts like it's low on refrigerant.

Right now this is what I'm getting:

Ambient: 55f
Low side (engine off, equalized): 60psi
Low side (compressor running): off at 30psi, on at 40psi, endless cycling
High side (compressor running): 100psi increasing to about 140psi, then it drops to 100psi again, and then maybe 1 second later the low side switch kicks in

When I jump the low switch it stays running constantly at about 25psi lowside and 100psi highside.

I can't figure out what's going on. I did some research and concluded the orifice was screwed up, since the low side is dropping so fast. It made sense that the compressor was sucking out all the 134a and cramming it into the condenser, where it was trapped by a broken orifice. HOWEVER now that I put the gauges on it, the fact that the high side is normal (ambient*2 +50) makes me think that isn't the case.

What I'd like to know is, at 45-55f how often should a healthy system be cycling? Is the problem the low pressure switch and not the orifice? Is this all normal for cold weather?

I am grateful for any help from you Jeep geniuses.

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post #2 of 6 Old 03-20-2017, 05:18 PM
greenmachine99
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If you put that much in you've definitely over charged the system. The compressor isn't going to cycle as much as it does in the summer. Here's a chart of where things need to be. Unfortunately you're best bet is to do your recharge on a nice day where it's 70+ ambient temp.
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post #3 of 6 Old 03-20-2017, 09:32 PM
Mousejockey
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*Disclaimer* Its been awhile since Ive done A/C work, but I can tell you its more than procedure and numbers with A/C. Hearing the system work, feeling the temp at various points, and a good ole sense of what is going on with ya see/feel


Your going to have to evacuate the system, to much is a bad thing
Did you add any oil when you charged the system?
You say there was debris in the system? The condenser may be clogged as well.
Sounds like the compressor vanes may of been damaged also. How much debris was in the orifice when you removed it? What did it look like?

Evacuate, change the orifice tube, Id recommend changing the receiver/dryer also, it has a desiccant bag to remove moisture.
Put it under a vacuum, let it sit for at least 15 min, if no drop then recharge and add about 1.5 oz of oil. then just under 2 cans of R134a. Use one can with the dye if you can.
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post #4 of 6 Old 03-20-2017, 09:48 PM Thread Starter
TheMatrix
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Quote:
Originally Posted by greenmachine99 View Post
If you put that much in you've definitely over charged the system. The compressor isn't going to cycle as much as it does in the summer. Here's a chart of where things need to be. Unfortunately you're best bet is to do your recharge on a nice day where it's 70+ ambient temp.
Thank you. I fully agree the system is overcharged, I was just baffled why it seems to be operating so well as such. I guess the only thing to do is wait until the weather warms up and look into it then. Thanks for the chart!
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post #5 of 6 Old 03-20-2017, 09:57 PM Thread Starter
TheMatrix
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Quote:
Originally Posted by Mousejockey View Post
*Disclaimer* Its been awhile since Ive done A/C work, but I can tell you its more than procedure and numbers with A/C. Hearing the system work, feeling the temp at various points, and a good ole sense of what is going on with ya see/feel


Your going to have to evacuate the system, to much is a bad thing
Did you add any oil when you charged the system?
You say there was debris in the system? The condenser may be clogged as well.
Sounds like the compressor vanes may of been damaged also. How much debris was in the orifice when you removed it? What did it look like?

Evacuate, change the orifice tube, Id recommend changing the receiver/dryer also, it has a desiccant bag to remove moisture.
Put it under a vacuum, let it sit for at least 15 min, if no drop then recharge and add about 1.5 oz of oil. then just under 2 cans of R134a. Use one can with the dye if you can.
Thanks for your reply. The previous owner appears to have injected an enormous amount of UV dye. :P The compressor was replaced 9 years ago, and has been functioning fine ever since. At that same time the orifice was replaced because it was full of debris, that's why I wanted to check it now while the system was empty. In those 9 years, only a few metal particles accumulated on the screen, so I would imagine the condenser is not clogged. I was going to change the the drier too - when I removed it to get to the HVAC box, the drier was very heavy - felt like it was half full of oil. Over the years I've put a few cans of 134a with oil in, and I'm thinking maybe there's too much. Obviously too little is a disastrous thing, but I'd imagine there is a limit to how much oil the system can handle... How does the oil circulate? Just ambiently in the system?
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post #6 of 6 Old 03-20-2017, 10:18 PM
Mousejockey
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Sounds like ya may need to flush the system. Get all that oil and debris out.
then you can get the proper amount of oil in the system.

While it is charged up, get the glasses and light to look for system leaks, when you find one clean off the dye with brake or carb cleaner, then recheck that spot in a day or two.

If it was me, Id rip it out and forget about it. My top is off once it warms up anyway. Now if it was on one of my other vehicles, Id seriously consider the compressor and a good flush on the condenser.
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