AC is still no good?

[HerbW]

Hi again. My AC is still no good. I bought AC gauge set, cans of 134A, Vacuum pump and UV dye. I put a charge off UV dye into the system and recharged it. I was going to vacuum it first but it still had pressure in both high and low just not enough. I then drove it for over a half an hour. All the pressures were to spec and the air was cold. I put Schrader valve caps on after leak testing them. Can the install of the caps cause a leak? The valves have UV dye in them due to gauges hooked up. The next day not enough low pressure to start the compressor! 10 lbs on low side and 30 lbs on high. I can't find any UV showing up anywhere. I caught about a quart of water out the AC drain and it looks clean enough to drink with dye not showing. I'm installing a UConnect system soon which involves the dash apart and maybe I'll remove the evaporator while apart. A LOT OF WORK TO DO IF UN-NECESSARY!

Can I remove the heater/AC fan under the dash and see the evaporator with a mirror and light? I want to see if my dye is there. I don't see any dye in the vents but I do see "glowing" lint on my floor and seats. Not much just a piece of lint that picks up the black light. I do know other things may glow similar.

thanks again, Herb

 

[jelag]

if you only used one can of dye... there is a good chance that might not be enough.... but I'm guessing that you have a leak under the dash if you did a good job looking for the dye at connections and around the compressor shaft.....

 

[HerbW]

I'm thinking the same. I took my air cleaner and passenger side battery box and followed all the lines out and there are no dye showing. I wiped clean my compressor and no dye or Pag oil. I have a very clean engine anyway as I wipe it down often. I bought a 134A gas sniffer tonight and will recharge and sniff for a leak tomorrow. I hope to find it.

 

[HerbW]

if you only used one can of dye... there is a good chance that might not be enough.... but I'm guessing that you have a leak under the dash if you did a good job looking for the dye at connections and around the compressor shaft.....

Jim,
Hi. I poured dye directly into my charge line and didn't use the 134a dye rechargers this time. It got a load!

 

[jhenderson]

I'm very interested in this thread. I've been chasing a leak for 6 months. No dye showing anywhere, and loses charge in exactly th same manner as Herb is experiencing. When it started I couldn't find the leak and took the dash apart. No evap leak but I changed it anyway. I would think if you had a leak in the dash it would show at the condensation drain at the firewall. I wouldn't pull the dash if I had no evidence of a leak there. My next move is a double dose of dye. I've been told that a sniffer only works on large leaks and that dye is more reliable.

 

[rscurtis]

The proper sniffer will find leaks as small as a quarter of a pound per year.

 

[HerbW]

Today I'm using gauges again and putting more UV dye into the line before charging it with 134a. I'll then use my new gas detector to sniff it. Darn I hope I find it with two methods going. I'll replace every part if that's what it takes. I'll let you know if I find anything.

 

[DavidC]

My daughters car had the elusive leak and was driving me off the deep end. Bought a sniffer, charged the system to spec and turned the vehicle off so no air was being batted around by the fan etc.. Bingo, one leaking valve and compressor front seal leaking. Replaced compressor and valve which cured the 2 year hunt. Those sniffers are worth the money and it helps if there is no wind and engine not running with a charged system.

Dave

 

[DavidC]

Forgot to mention, you can stick the sniffer probe up the condensate drain to sniff evaporator (rubber glove not required, HA). Just make sure system is charged and everything is turned off, fan etc.

Dave

 

[BIGNASTY]

Forgot to mention, you can stick the sniffer probe up the condensate drain to sniff evaporator (rubber glove not required, HA). Just make sure system is charged and everything is turned off, fan etc.

Dave

I have never had any problems with my AC, I was told to run the system even during the winter for at least some time to keep everything up and running. My Son that has a hard time remembering things has had problems with his, I asked him if he runs it? I forgot, well take it to a Pard in Missoula that works on refrigeration equipment on large trucks and see what he can do for you.

He has a sniffer and found his problem within minutes, sometimes it pays to go to a professional that knows what is going on rather than waste time and money to fix it yourself. It was really nothing in his case and fixed it in no time, told him your Dad owes me a beer next time he sees me.

 

[jhenderson]

I am going on info available to me here in RI. We don't have any AC only shops in the state. It doesn't get that hot for that long. Most shops and guys like me have only basic knowledge and tools on hand. I'm sure you folks in hot climates have far more experience and higher quality tools for the job. Thanks for the tip on the sniffer. I'm waiting for the outcome.

 

[HerbW]

The front seal on the compressor sniffs max leak after I recharged the system. I sniffed the drain, vents, lines, switch connections and they are all negative tested. I can reassemble my dash now after UConnect install yesterday. I noticed my clean fingers are UV dye stained even though I didn't ever see it on the compressor. I just order a full kit with new dryer, proper oil and compressor. Looking forward to install, vacuum and charge it. I'm going to pull the compressor clutch on it and see if there is more dye there for something to do! LOL

 

[DavidC]

At least you found it, gives you a chance to check your vacuum pump now. Do you have a scale ?. it is really the only way to charge the system accurately. Pressures will not do it as environmental issues are always changing which then changes pressures.


Dave

 

[Motorhead]

Dave, the trouble with relying on a scale only to charge is what do you do if you have a partial charge? There are charts you can find online that give you what the pressures should be at a selected ambient temperature. There are also charts that tell you what the STATIC pressures or the pressure of the system with gauges hooked up but the A/C NOT turned on. I have a Klein volt/ohm/amp meter that also has a temperature thermocouple that I put into the center A/C duct and read my outlet temperature.
When I replaced the compressor in my '07 with a new compressor, I completely cleaned my system internals, replaced the receiver dryer, expansion tube and installed DuraCool R12a refrigerant. From when the truck was brand new, I could only get 52-53 degrees out of the center vent. Same with my old'01.5 too. With the DuraCool, I am getting 41 degrees out of the center duct, even on the hottest days.

 

[JR]

As many times as the system has been vented off due to the leak make sure you pull a good vacuum on the system...the longer the better.
Also I didn't see where you mentioned it but it would be a good idea to at least inspect your expansion valve while you've got everything opened up for any pluggage or holes. They are only a few bucks and I just replace them when I'm into a system for a compressor/accumulator job.

 

[HerbW]

JR. Sounds like a good idea.
Dave, I don't have a scale.

 

[DavidC]

Dave, the trouble with relying on a scale only to charge is what do you do if you have a partial charge? There are charts you can find online that give you what the pressures should be at a selected ambient temperature. There are also charts that tell you what the STATIC pressures or the pressure of the system with gauges hooked up but the A/C NOT turned on. I have a Klein volt/ohm/amp meter that also has a temperature thermocouple that I put into the center A/C duct and read my outlet temperature.
When I replaced the compressor in my '07 with a new compressor, I completely cleaned my system internals, replaced the receiver dryer, expansion tube and installed DuraCool R12a refrigerant. From when the truck was brand new, I could only get 52-53 degrees out of the center vent. Same with my old'01.5 too. With the DuraCool, I am getting 41 degrees out of the center duct, even on the hottest days.

Yes a partial charge is a problem as we do not own recovery systems. Herb's system will be empty that is the reason I mentioned a scale. If there is a partial charge and no recovery then pressure is all there is to work with that I know of, besides temps from the registers. With R134 it is very temperamental with under-over charge and outside temps can make it difficult to get it right, but if you can get it close and your happy that is all that matters.

Dave