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A/C overcharged(not cold)

65K views 53 replies 8 participants last post by  alvin 
#1 ·
Well now I am trying to figure out another problem with my buddy's gc. The past couple of days has been hot so we have been using the a/c. Well the a/c is cool but not cold. I have one of those refill and gauge kits for the a/c. Well the gauge tells me that it may be overcharged. Is that the reason why its not cold? Or is there a valve not opening all the way so it reads overcharged? The rad fans now work so air is moving threw the radiator area. Can I let some of the freon out? Any suggestions are welcome. Thanks.
 
#2 ·
This might be a silly question but you are checking the level with it running and the AC on right? I know if you look at it with it off it will read high. Just a thought. The proper way to remove would be to vac it out but if you had trouble getting the hose on and some came out who would know the difference?
 
#3 ·
Yes I am checking it with it running. Thats how I was planning to try to get some of the freon out(sometimes that connector doesn't like to connect nice and tight:biggrin:.)But I don't know if there was another reason why it is overcharged. There is a sticker on there that says dodge was locating a leak and put die in it, but that was many years ago.
 
#4 ·
If you have very high pressure on the high side, which is usually all the little refill gauges read, you almost certainly have a stuck H valve, or metering valve. Typically it is bolted to the firewall where the pressure hose bolts to the firewall. There is a square block that the hose bolts to. They typically get ashed up on the valve and stop working. I have replaced 5 over the years and they act like they are low on freon, fog coming from the vents, but when you measure the pressure, it is very high on the pressure side and not much on the suction side, since nothing is coming through. You can replace it yourself. Get new ones, if you have someone that can salvage the freon (suck it out) that is a nice thing, they can even reinstall it when it is fixed if they are set up right. But if you are in the back yard, you can release it with the schrader valve, do it slowly so oil does not go everywhere. Once the pressure is off, unbolt and tape over the pipes to keep moisture from getting in. Replace the block, using new seals, aluminum, and vacuum out the system. If you do not leave the system open and replace the block quickly, you should not have to replace the drier, but it is recommended any time you open the system. Note if significant amounts of oil spill and replace about what you think got out. Pull a vacuum (or better yet pressurize it with nitrogen, see if it holds or if the pressure changes overnight.) Some manuals warn against leaving vacuum on the system for extended periods. If it holds, refill the system and you are good to go. Do not dump liquid refrigerant in the suction side, let it boil off as a gas can rightside up, put in warm (not hot) water, or hose down, if needed. If you do the best way, you will need a lot of equipment. If you do it yourself, you will have to go somewhere to get a vacuum pulled on the system. If you have a compressor, you can get a cheap vacuum generator that hooks to an air line (if you have the cfm). Happy AC fixins.
 
#5 ·
TCWAGNER1 has some good recommendations, however, before you do anything, you might wish to share your observations with us that have brought you to this conclusion in the first place.

What's your "HI" pressure, what's your "LO" pressure. While the vehicle is stationary, are you running water on, or an external fan blowing in front of the grille, to keep the condenser cool (sitting stationary for an extended time, with no adequate cooling of the condenser will show a high head pressure -- even if your internal fan is running)?

Did you replace the A/C compressor, or is this the original one?

Need more info, before throwing ideas blindly at it.
 
#6 ·
I think the kit I have only connects to the low side. I will have to look at it later to see what pressure it says but it said it was overcharged. Yes the radiator fans are running so air is moving threw the condenser. The compressor as far as I know is original.
 
#9 ·
There is one other possibility you might try before doing anything else. Make sure the condenser is not choked with bugs. Can you touch pipe coming from the condenser (the part in front of the radiator, without burning yourself? (Careful, spit of the finger, like an iron, don't grab it!) It will be hot, but if it is too hot coming back from the condenser, it could be plugged with metal from an old change out or it could be full of bugs. I had one that was not cooling, showed high pressure, took it to a AC friend, he noticed the heat was too high on this pipe. Took a hose with a pressure nozzle and shot out the condenser grill, suddenly it cooled again and needed no refrigerant. Here in Florida we have mosquitoes and "love bugs" that will choke a condenser quite easily. You might try checking that first.
 
#10 ·
Its not full of bugs but there is some white build up in some of the condensor fins. I will try to clean the best I can.

Also I got the pressures of the a/c when off and running. With the car off, the pressure was reading 65 psi(that is border line warning/ alert) and with the a/c running I got 47 psi(border line Alert/filled) So the psi is dropping so maybe it is just overfilled. If overfilled, will that make it not cold, just cool.
 
#11 · (Edited)
FSM shows a way to check the charge level, by reading both pressure and line temperature on the high side. The temperature can be measured with a meter that works with a plug-in thermocouple. In fact, the manual says how to measure the subcooling, without calling it that, and shows a chart which tells you whether it's a correct charge, undercharge, or overcharge. If you have > 40 psi on the low side, it can be undercharged too, but the only way to tell is to measure the high side. If it's, say, 150 psi, it's undercharged and the low-side pressure is too high because the expansion valve is fully open. If you see 400 psi, then it's overcharged.
 
#12 ·
I think your gauge is screwy. 47 psi is not even low pressure for one of these systems, as I remember. Maybe that is metric or something. Try to get a reliable set of gauges on the system before going any further. You can get the adapters to fit auto, if you only have the HVAC type, from NAPA.
 
#14 ·
According to my gauge 47 psi is almost to the filled range(which is what I want) but inorder to get in the fill range it has to be 45 psi or something like that. But that is on the high side of the filled range. So I guess I have a little room to play with in the filled section. So I am almost there. I am going to call around today to see who I can rent a set of dual gauges from.


Thanks everyone. I will come back when I found more out. Well off to work.
 
#13 ·
Overcharging a system will not make it cool better, but simply screw up yout pressures, however, unless you are reading both high and low pressures, you will not know whether your system is charged correctly or not. Basing your pressures on just one side of a system is like turning on a faucet and setting the empty glass on the counter. Or simply put, just a mere waste of time.

High pressure on the low side can mean several things, high pressure in the high side can mean several things, but you are only looking at part of the picture. Gotta get gauges on both sided.

Oh and if it is overcharged, 134a is more ozone friendly than that old r12, just so you dont feel guilty if you have a little issue geting those guages hooked up correctly
 
#17 · (Edited)
Sorry, my first post I said high side, I meant to say low side, I actually have one of these , it was late, sorry. If you buy a set of gauges make sure it will connect to cars. I haven't read through all the posts, but I am assuming you are
R134. You may need to buy adapters, and they can be purchased at either NAPA or at a HVAC supplier. Harbor freight has them for less than you are quoting, but I don't know if they have the adapters either. But don't hook up unless you know how to use these things. If you pressurize the can from the high side you risk an explosion, and you can do it by simply being careless. You may really find it beneficial to get with someone who knows the first time and let them explain it to you. Your eyeballs are hard to replace. Just a thought.
 
#19 ·
That looks like it, if you have R134. But again, do get to know the kit before you hook up and try to add freon. Don't dump liquid freon into the system, it can damage the compressor. Let it boil off as gas (can right side up) put it in a pan of water (not hot, just water) or run a hose on it to boil it off. Don't allow pressure from the high side go to the can of freon, it can explode. Most guys when they first put the hoses on, don't get them on tight, just start to attach them, then blow some freon out through the hoses to clear air, and any moisture out, prior to pumping it into the system. I would really just go somewhere and pick an AC guys brain on whatever he may tell you. There are probably some folks here who could tell you much better than me, it has been a while. By the way, Advance Auto has everything AC on sale right now, including cans of leak detector. FYI.
 
#20 ·
I'd mention that it's worth the expense to get service port connectors with manual valve depressors (thumbwheels). With them, you can take your time installing the adapters to the ports without letting out any refrigerant. Very handy in tight spots, such as the high side in this case. And when you're done, before shutting the engine you can close the valve on the high side, open the high side valve at the gauge and have the refrigerant from all three hoses sucked into the system through the low-pressure port.
 
#22 ·
Well I got my pressures and I am living to tell about it. Nothing bad happened:biggrin:. Anyways here are my pressures. With the van off, I got 70 psi on the low and high side. Once I started it up and ran the a/c it built up till a couple seconds later the fans kicked in. After 5 minutes at idle I got 25psi on the low side and 150 psi on the high side. After 10 minutes I got 30 psi on the low side and 160 on the high side. Sometime later it would change to 35-40 on the low side to 190 on the high side. If I run it at about 1500 rpm I would get anywhere from 20-25 psi on the low side and 200 psi on the high side. It is kinda of fun watching the gauges when the compressor turns on and off. I can find anything in my manual about the pressures I want, so if anybody can help out again, it is much appechiated.
 
#40 ·
Well I got my pressures and I am living to tell about it. Nothing bad happened:biggrin:. Anyways here are my pressures. With the van off, I got 70 psi on the low and high side. Once I started it up and ran the a/c it built up till a couple seconds later the fans kicked in. After 5 minutes at idle I got 25psi on the low side and 150 psi on the high side. After 10 minutes I got 30 psi on the low side and 160 on the high side. Sometime later it would change to 35-40 on the low side to 190 on the high side. If I run it at about 1500 rpm I would get anywhere from 20-25 psi on the low side and 200 psi on the high side.
You need to check your manual for MAX pressures on the "HI" side. I'm guessing, since I last did mine over 3 years, ago. However, I do recall the "HI" side being around 300 - 350psi and the "LO" side being around 40 - 45psi.

Your pressures tell me you're actually too low, not, too high.

I also recall, I did NOT begin getting any "COOL" air coming out, til I was atleast to 250psi on the "HI" side.

It is kinda of fun watching the gauges when the compressor turns on and off. I can find anything in my manual about the pressures I want, so if anybody can help out again, it is much appreciated.
Yes, it's very interesting to see what happens as the system cycles. This is "GOOD" news. Sounds like you're just too low, and can use another 6 - 12oz of freon. :thumb:
 
#28 ·
If you have normal pressures, you might check to see if the vacuum motor on the heater door is working. It may be stuck open, heating the cool air, like when you want to defrost the windshield. Doesn't sound like expansion blocks. But you said front and back aren't working, Right?
 
#30 ·
At first the air is sorta cold but nothing like a real a/c should feel like. Then after a while it kinda dies down to just cool. It is the same for the front and back. I felt the lines going to the back and one was cold and the other was warm. Also is the vents in the ceiling surpose to be blowing alotta air? Mine don't. It doesn't matter if you have the a/c on or heat.
 
#34 ·
Sounds more like a stuck door or control for temperature.
 
#37 ·
I am not exactly sure how you see the motors on your model, but I would start with a flashlight and look up under the dash from the floorboard. Some are easy to see if you just remove the glove box. move the controls and see if you see the motor move anything.
 
#41 ·
Have you checked the sight glass on top of the drier? if you are low, typically you will see foam, white, instead of clear. You may have to clean the top, there is a round hole in the middle of the drier and some times it is even painted over. If it is well charged, it should not have foam to any extent. My recollection is as AZT. Mine was actually charged higher than that with R134a until I put a new compressor in and went back to R12.
 
#46 ·
You will see the two pipes bolted on each side of the top of the drier. The piece in the middle is the drier and the sight glass should be in the middle of that piece of middle, about a 3/16 round spot, could be painted over, could have tape over it you may have to remove from the whole top of hte piece.
 
#47 ·
Is the drier behind the air box and below the wiper crowl? I see two lines coming to it and both are bolted down, but I see no glass. I guess I will have to look harder when I go over there today.
 
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