I am a little lost on this one guys and would appreciate some help on it. The other day I heard a loud bang while driving that sounded like a gun shot. I pulled over and nothing obvious except my AC wasnt working. When I got home I put the low side preasure gauge on and preasures were at 130PSI constant! I purged some of the preasure and the AC started to cycle. Heres where it gets strange. Sometimes when the compressor would kick in and it would run from 20 to 25PSI then the next time would be from 35-45PSI. Then it would go back to 20-25PSI and skyrocket back into the red area on the gauge and kick out at approx 115PSI! Then preasures would be low again. Strangely The compressor is working but I am still not getting cool air out the vents.
When I bought the truck about a month ago the AC was weak. A little freon fixed it for a day then it was hot again. I tried adding that leak stopper/dye into the system and it worked great for a few days till the big bang incident. Now with the preasure fluctuations I am lost on how to fix it. Even venting the system and starting over with 2 cans of freon has the preasure fluctuations. What should I do now.

 

I think You need to have the system properly exacuated and start over.

 

Thanks for the reply tool. I agree with you one having the system evacted and refilled with freon but it sure seems like something is going bad. I would prefer to fix the thing before putting money into the evac and recharge to just have to do it again. Any ideas what might be wrong with this thing?

 

If your truck is still in warrenty, i would take it in, sounds like something might have broke in the compressor.

 

www.acsource.net/acforum/ This place may help. good luck Jim

 

RAM2940, The truck is a 95 and way out of warranty unfortunatley. I dont know what happened to my sig. Have to check my profile.
JIMK, I will check that website out and see what I can find. I hope that its not the compressor as I have a bad tierod saying that it wants money too in the near future.

 

Just a side note, but in the title to this thread you use the term 'freon".
Shouldnt it read R-134A?

 

Sounds to me that the system had moisture in it when you put the freon in. That bang was probably the A/C compressor letting go.

 

You are right CSA it is R-134A. Its probably wrong but we say freon as a general word for the coolant.
JEREMY the wierd thing about the big boom was that after it happened the AC was dead. If the compressor blew wouldnt all the R134a be released from the system? When I got home and lowered the preasure on the low side is started cycling again. Acting just like a good working system except no cold air. I am getting condensation on the low side lines and the high sides are hot. When I first bought the truck if I started it with the AC on it did sound like a an old fashioned perculator coffee pot for maybe 5 seconds then nice and quiet again.

 

I have a 95 also here is a place to buy parts and I have use them, great guys to deal with. www.techchoice.com

or 972-723-0112 hope this helps Jim

 

I have to wonder if you have something that came loose in the system, perhaps a seal, and it's getting into someplace, like the orifice tube, at times and restricting flow, which causes the spike in the pressure. Problem with that particular theory is that the orifice tube is between the high and low side, flowing to the low side, so if it was the restriction you'd see the high side pressure rise and low side pressure drop.
On the low side there is only the filter/drier between the evaporator and compressor.
You get NO cold air, even though the line is getting cold?

Chris

 

What are your high side pressures? Are they extremely high or do they bounce around like your low side is doing. Just thinking if you had to much refridgerant in the system that it might not be boiling off before it gets to the compressor. Could have damaged a seal in the compressor that is sealing intermittantly. If you are getting 130 on low side acts like the compressor has equalized.

 

It sounds like the seal blowed between the low and high side in the compressor. This could cause the pressure to go up and down. When the high side builds pressure the bad seal lets it though to the low side. The refrigerant from the high side would keep the system from cooling.

You can always take it to the shop and have them check it out. There could be something here that we are missing.

 

My Grand Cherokee did the same thing after sealer was added. The filter/orfice was plugged by the sealer. Replaced it and put a vacuum on the system, replaced the freon (Yes that is a proper term for it, there are several freons out there, 134, 12 22 etc.) and it works properly again. The 2nd gen Rams are notorious for the evaporator under the dash to develope a leak and the best way to fix them is to replace it. The sealants offer a quick fix but it is costly in the long run because it plugs up everything. If you have noticed a funky smell in the cab it is probably the evaporator.

 

Sorry I havent had a chance to respond till now. I worked till 8:45 tonight.
I dont have a high side gauge so I cant tell you about those readings. Right now I am building condinsation on the lines but no cold air at all in the cab. If anything it may be slightly warmer than outside air temp.
The system has 2 cans (24 oz) of freon in it after venting all preasure at the low side schrader valve. This is when I got the low side readings That I posted. They are consistant with the preventing readings after the big boom also. The sealer I added previously had dye in it and I havent seen any under the hood. However I do need to take a closer look at it this weekend to be sure. The inside of the truck has had a musty smell since day one if the windows are shut up in the heat but is getting better/not as bad.
I might be able to pull in a favor on monday and get a residential/commercial AC guy to take a look at it. I got my fingers crossed. I really hope that I can get this fixed for cheap. If the compressor is fried I cant afford to fix right now. Seems like all the new compressors are $350-$400 after core and shipping charges. How hard is it to change seals in these things? I am a compitant mechanic, just not an AC guy. It would sure be nice to have AC the remainder of the summer. Up till last week its been in the 90s with a heat index between 105 and 115 and I work outside. Keep the thoughts coming guys. I sure appreciate the help.