Air Conditioner High Pressure Max ????

4x4dually

4x4dually

Moderator
Staff member
Joined
Jan 22, 2007
Messages
32,083
When throwing in some R-134A, what high side pressure do you folks normally charge to? I use dad's machine when I can, but I put a can in every now and then when it gets low. I normally stop at 200 psi on the high side. What do you all do?
 
how often do you have to put a can in?

Do you ever put any oil in it? You might be low on that as well.
 
I have to add a can about every month once it warms up in the spring. Dad has a body shop and a real nice Robin Air reclaim/charge console that will add the correct amount of refrigerant and oil and all that crap; however, he is an hour away and in between those fancy charges, I just add a can with manual gauges. I have put a can of that "leak stop" 134A in there and it doesn't appear to stop the leak. I've also use a leak detector that he has and sniffed every inch of it under the hood. I either have leak in the compressor that I can't sniff or it is under the dash in the core. I've checked the air coming out of the vents but I imagine the ppm is so low there I'll never detect it. I figure it is cheaper to add a $7 can every month than a couple hundred on a compressor or tearing the dash all apart.

So, I just want to make sure I don't pressurize it too much.

We've also done a vacuum check on it and you can tell in about 15 minutes that the vac leaks off ever so slowly, so slow, we have to really look to see it.
 
No I haven't. I got contact, will that work? J/K. I haven't seen the glasses. I'll have to look for them. Thanks.
 
Thanks! I hope oil leaks don't show up! :hehe: The whole dayum thing will glow! LOL
 
The only thing that will glow is what has the dye in it. So your leak in your ac should just glow
other oil leans won't unless you put the dye in that system as well.

it will cost you around $50 to find the leak. that can buy a fair amount of r134a for that price. but then you have the kit for future use.
 
On the old R12 systems we used to use ambient temp plus 100. In other words if it was 80 degrees out, then the high side pressure was 180 when full. With R134, the norm is ambient temp + 100 + 15-20%, so with 80 degrees out it would be around 216psi on the high side. Your 200psi is pretty close.

Paul
 
their should be a data tag under your hood with r134a info on it . it will tell you the correct amount of freon in your system ( by weight ). the most accurate way to check it ,would be to recover what freon is left in your system and recharge by weight. over charging your system will cause it to perform less than peak performance. but it will work. if you do put a sealent in the system to try to stop the leak and later recover the freon , please make sure the machine your are using has a sealent filter on it .you don't want to plug up a costly machine. i learned that the hard way
 
I haven't hooked it up to dad's machine since the leak selant, but I will mention that to him the next time we go to do a "proper service" on it. I may have to take it somewhere and ruin someone else's machine. LOL J/K. When he retires, that bad boy will be in my garage if I have any say in it.
 
Try putting your sniffer at the drain pipe for the HVAC system under the hood. If you are adding oil, you may also notice it coming from the drain pipe. Evaporator cores are the most common leak points in 2nd gen trucks. I replaced my evaporator last year, and it was not near as bad as people made it out to be. It took me about 3 hours from start to finish.
 
Another great idea hogg. Thanks. I'll check the drain for oil when it stops raining like a banshee. :D
 
Back to your very first post, you want to know what to go to on the high pressure side when adding freon. It depends on the temp, the humidity, your engine speed (rpm), and amount of air flow to the condenser when your adding. Are you just shooting a can in there and calling it good? Cause that aint right.

Do you have a shop manual on the truck?
 
In the Dodge manual, it always has you evacuate the ac system and then add the amount of R134a that is listed on the vehicle sticker. The only high pressure readings it gives are for testing, and they are a large range. They should not be used for adding R134a. Yes the only correct way is to completely evacuate the system, and then refill with the specified amount. As I understand it, that wasn't the question that the OP asked.

Paul
 
Anyone have any info on adding additional oil?

Service manual explain it pretty well, or does anyone have tricks of the trade for doing it?
 
You must log in or register to reply here.
Back
Top