Having problems with my 2001.

Last year I had one of the small electrical connectors on the rear of the compressor that was hanging and rubbing on my A/C lines. They eventually wore a hole through my line.

I bought a new liquid line including orifice and receiver. Installed them along with 4 oz of oil, evacuated the system then tried to charge it.

I could not get it to take a charge on the low side. Like there was some kind of restriction in the line. So I shut it down and charged it on the high side. The funny thing was that as it started taking refrigerant on the high side the pressure did come up on the low side. It took a while but I did manage to get a full charge into the system. Once I fired it up it worked fine.

This past week it started short cycling. Put my gauges on it and it is sitting at 90 psi on the low side and 110 on the high while short cycling. Thinking I may have a bad switch I jumped the relay and it froze the low side after the orifice but the gauge never changed from 90 psi on the low side!!! The high never got above 120.

Everything screams that I may have a restricted line, but I don't know what else to check. Last year when I changed the receiver, and liquid/orifice line, I couldn't get it to charge on the low side, I had to basically back charge it through the high side with the engine off. Now I am trying to figure out what else could be blocking a line. On the old expansion valve systems it was usually the expansion valve, but this one doesn't have one that I can see, it just uses the orifice.

Am I missing something? Is there some other component that could be blocked in this system? It does cool, but with it short cycling and not building pressure, it just isn't cutting it in our heat and humidity. In the mornings it works well, but once it heats up outside it just can't keep up. I am wondering where else to look for a possible restriction.

Any suggestions would be appreciated.

-Dave

 

Shovelhead,

On our trucks the orifice tube is in the liquid line that runs from the condenser behind the battery and air box over to the receiver/dryer. That was replaced already along with the receiver dryer. You cannot replace just the orifice, it is made into the line (thanks Dodge.)

The low side pressure port is after the orifice, but before the receiver dryer. That is what doesn't make sense. I can jump the compressor relay and literally ice up that line and still see 90 psi on the low side gauge. Since pressure and temperature are relative, I should be seeing below 30lbs to freeze that line the way it does. With the system short cycling it makes me think the pressure switch is working at the receiver.

Oh hell, after typing this I just realized that the restriction my not be in my system, but in my gauge set or line.....

I will check them tonight and post what I find.

-Dave

 

Man you are playing with your life... You should NEVER recharge an AC system from the HP side. I didn't think anyone had done it since the law suit back in the late 70's after which all the auto manufacturers made the high side fitting a different size. A side from that it is impossible to recharge the system fully using the hp side as the pressure from the compressor will almost right away be greater than the pressure of the freon in the freon container. There becomes a point where you are actually blowing up the freon container, literally.

 

Busboy,

You probably missed it in the way I worded my earlier posts, but I DID NOT HAVE THE ENGINE RUNNING. I know better. I had everything shut down and managed to get enough in the system to last me for almost a year now.

Good safety tip you posted, but I was aware of the possibility of the container exploding, that is why I shut it down and put my charge in with the engine off.

Now for the good news. It was my low side charge hose on my manifold gage set with the problem. The quick connect fitting is rebuild-able on mine, and it had backed off about 5 threads where the fitting comes apart. That was just enough that it would not leak, but it also could not clear the charge holes in the fitting. Basically the low side pressure I was seeing was what was trapped in the hose.

Once I tightened up my hose fitting parts, it worked like a champ. I was in fact low on refrigerant. It was building up 120lbs high, and was sucking down to 20 or so on the low side and short cycling.

It took just about 3/4 of a can to get me back up and running. Now I am pulling 36 low and 260 high at 80 something ambient with lots of humidity.

All is well. Thanks for helping me pick my brain!

-Dave

 

GTS, thanks for posting the solution. Based upon your initial post I would have bet you got a bad line originally, I would never have thought about the gauge set, at least until after I had replaced a new line set.............

 

Glad you found the problem, you must realize may people read these posts and perhaps are not as experienced in AC work. After re-reading your post I do see where you say "you shut it down" but most people think of "recharging" with the engine running. In some ways I like the old style fittings better.

 

It didn't even occur to me to put in a safety disclaimer until you pointed out. I should have worded my post better. You were right on to point out the danger about charging back through the high side lines.

For those that missed it,

NEVER EVER CHARGE THE HIGH SIDE LINE WITH THE ENGINE AND A/C RUNNING. THE CAN OF REFRIGERANT WILL EXPLODE IN YOUR FACE AND POSSIBLY KILL YOU

What I did was charge refrigerant back through the high side line with the engine off because I thought I may have had a blocked schrader valve at the low side port. My error was in completely trusting my equipment, when in fact my low side charge hose connection was malfunctioning. I was first ASE certified back in 1986, but have been out of the business for many years now. I knew the danger involved and made sure to take precautions. I didn't stop to think about who may read and misinterpret my post.

I should have been MUCH clearer in my original post. Someone who does not know the danger could get hurt. If you are not experienced with these systems please trust it to a professional, the pressures these systems generate could turn that can of refrigerant into a grenade and kill you are a bystander.

-Dave