Same subject, different symptoms, I think. My 98 is overheating with the a/c on at slow speeds or in park. The problem is unchanged or slightly worse after giving it a store-bought recharge. Hissing is noticeable and a good deal of water drops when engine is shut off, but no coolant is obviously leaking. Need to check the pressures against the troubleshooting chart above. But, my question is about the compressor clutch. It seems prone to disengaging at idle. Is this something that can be solved with the removal of a shim from the compressor as I've read about previously?

 

Leads me to believe it is overcharged. While it is normal to hiss after you shut it off and drop condensation, I think it may be shutting it's self off when the pressure is getting too high in certain conditions like in traffic hot at an idle. This is when an over pressure condition presents it's self.

Do you know if they just topped it off, or if they vacuumed it down and started from scratch? How much refrigerant did they charge you for?

 

I meant to say that I did the recharge myself with a store-bought can of r134. Used about half of the can to bring pressure up to the suggested, temp-adjusted level on the gauge that came with the kit. I noticed it was cycling funny after the recharge - pressure would rise and dive as compressor kicked off and on. Seems like overcharging is an issue that fits some of the symptoms, like you say. I'll check lo and hi side pressures and revert. Thanks.

 

oh I see. Please let us know.

 

I thought I would say something here about charging with that little gauge on the can. You can get away with that, sort of if you have the type of system that has a fixed orifice. If you have an early XJ, those have a TXV located on the liquid line right next to the firewall. What it does is monitor superheat, which I will not go into here because none of you have the equipment to charge that way. But these system are charged by monitoring the liquid line and that little gauge on the can is worthless for these systems. The way you charge these types is with the sight glass on the top of the filter/dryer. You will see little bubbles go by in the glass. When they get to where they look sort of like fog, then it is fully charged. If you use that gauge you will greatly overcharge the system

 

Just ran into something important that needs to be shared. Was topping off the system in my Truck and found something we all need to watch for. Apparently they are putting out cans with improper instructions on the side.



This is INCORRECT! Freon R134a cans like this need to always be held upside down to charge the liquid rather than the gas into system. Getting enough Freon in the system to make it work properly as a gas before encountering an over pressure issue is next to impossible. It needs to go in slowly as a liquid.

I tested this can to see if it may have a tube attached inside that went down into the liquid like a paint can does and it did not. I was only getting liquid when it was held upside down as all other R134a cans do. So this arrow is backwards and is going to cause problems properly recharging systems.

Keep an eye out for this discrepancy guys. You can tell if you are getting liquid because your gauge needle will not remain steady as it goes in, it will flutter a bit as the liquid is going in.

 

Agreed

 

I saw that and was like "What???" Checked it as soon as I opened the service tap from the can to make sure I was getting liquid and found it to be wrong.

This little discrepancy would cause folks to give up trying to get it right by themselves and take it to a shop without real reason to.

 

I have always charged with the bottle upside down, even the 22 pounders. I have personally seen an R22 large bottle get so cold from syphoning vapor off that ice was forming on the outside and it wouldn't charge the system any more because the vapor pressure inside the bottle was less than the pressure on the low side of the undercharged system. So, the bottle always goes upside down and I feed it a little at a time

 

Interesting. I learned from an experienced auto AC technician to charge refrigerant as a gas, bottle right-side up, and that charging as a liquid can damage the compressor. That was back in R12 days and I've continued the practice with R134. I use a coffee-can filled with water on a hot plate to warm up the refrigerant can. This raises the vapor pressure and forces the refrigerant into the AC system. Have not had any problems doing it this way.

 

He is correct. You can not compress a liquid.

 

You are absolutely correct. The carry handle on the R22 cans are even built to be used as a stand when it's upside down during use. You have to charge it with liquid, but this is where the patience comes in, it has to be done slowly as you say.

And yes they equalize in pressure and you can't get enough in to make it work properly.

 

If you put it in too fast it will lock it up. Trickle it in slowly and it will evaporate inside the system before it reaches the compressor. Tell you what, Just try to get enough in a system when the ambient temp is 120 degrees or more out loading it as a gas. You will not get enough in it to make it work properly.

 

It evaporates to a gas in the system before it gets to the compressor.

 

I can see where that would be the case. Fortunately around here summer temperatures are typically in the mid-80s to mid-90s, though they will reach 100 degrees on occasion (like last week). Heating the small refrigerant cans in hot water has worked quite well under these conditions.

I even have an old "Dial-A-Charge" charging cylinder for heating and measuring bulk R12 but it has not been used since that refrigerant was phased out. You'd load it up with liquid R12 from a large canister and plug in the heater which would force the gas out, and track the amount charged in via printed scales on the glass. (I suppose it could be used with R134 as well but the printed weight scales would be off.)



(Yes, the gauge is correct. After sitting for something like 20 years there is still some residual R12 gas in there.)