MN Ben
Minnesota
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So after the rebuild and radiator/oil cooler flush and clean I need to recharge my cab A/C.
When I took this thing apart, the cold stuff came out of it just fine. Yesterday the shop guy gets around to checking the gaskets and stuff. We decide to switch from freon to 134 refrigerant. He calls this morning to tell me that he put a charge in it last night and this morning it had not kept the pressure and it will need new hoses.
A couple of questions....
1-I heard that a different type of gas is used initally to check for leaks as to not waste the refrigerant, true?
2-A bunch of freon came out when I dismantled it....so now the hoses are leaking???
3-Should this job actually take 4 days to do?
(freon was $4.30/oz and 134 refrig is $1.16/oz. I was told it will take 3# of charge)
Ben
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Gale Hawkins
Murray, KY
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Joined: 07/22/2007
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Ben it does not add up. It is true the current gas can get out of smaller holes than R-12 but that should not be so in your case. If it was holding R-12 OK then it should have been OK with the R-134a in my few cases of converting from R-12 and especially in a chassis from the early 90's. I have the 1992 P30 chassis with factory air. By the way expect some comments about releasing R-12 but just tell them it is the last time you will do it on that MH. 
Expect a sealing issue at the points where you opened the system OR the shop did not get a good seal on the retro nipple(s). Due to recoring I just went through the same thing except the conversion was done before the radiator job.
An A/C shop charged me $20 labor to pump it down. The R-134a recharging was $32 for total of $52 to get cool again by a quality automotive A/C shop in town. Best of luck and update us.
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HENZEN9
SPOKANE, WA
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Joined: 04/16/2007
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Ben, I agree. You should look up on the internet 'DIY AUTO AIR CONDITIONER REPAIR' You will get more info than you thought possible. I just put a new accumulator on my Ford pickup and recharged the system with one of tghe cheap kits purchased at Napa. Everything is easy and straight forward. Allen
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HPH
Texas
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Joined: 04/20/2008
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If he's saying the sys. is now empty then I would say the leak is at one of the connections that was taken apart. There is a difference between operating pressures and standing pressure so it is possible that your sys. had enough gas to "purge" but not enough to properly operate. It is true we sometimes use nitrogen to pressure up a sys. to ck. for leaks. I do not on automotive a/c as the amount required is ounces and I was paying 79.99 for 30# drums of 134a last fall. It may be up now that summers here though.
It doesn't take 4 days to do the job but that maybe due to his work load. You may find the condenser is too small now w/134a. Was all the mineral oil removed?
Good luck.
HPH
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MN Ben
Minnesota
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HENZEN9 wrote:Ben, I agree. You should look up on the internet 'DIY AUTO AIR CONDITIONER REPAIR' You will get more info than you thought possible. I just put a new accumulator on my Ford pickup and recharged the system with one of tghe cheap kits purchased at Napa. Everything is easy and straight forward. Allen
I would have done this, but I feel I would have spent the $ at NAPA and then something would have gone wrong. (I would not have thought to check for bad o-rings) I would have had to spent more $ at a shop to get it right.
This is exactly what happened to my ride-share friend.
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CISCO8325
Peoria,az.
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Joined: 07/21/2006
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when you reto the r12 to 134a you need to change out the o-rings. The part you took apart needs new o-ring. the r12 are black and the 134 is I think green or blue. Anytime you open a system you need to change o-rings..It easy and cheap. the 134 you can get anywhere. The other thing it may need when retro is changing the dryer and compressor oil..LOL
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j-d
Sunny Florida USA
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Joined: 09/04/2003
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www.acsource.net/acforum
may be able to help you. It'd help to know what vehicle/chassis/ac setup you're working on. R134A has a smaller molecule size than R12 and "barrier hose", along with BeadLock fittings came in to replace non-barrier and "finger lock" joints. It turned out, though, that old hose that wasn't already leaking R12 had built up an oil "barrier" and R134A was not being lost as predicted. As time went on, the retrofit rules actually got less complicated. New Barrier Hose such as Goodyear Galaxy, along with the correct connections (barbed fittings are not used, BeadLock requires fittings with recessed grooved), is always a good idea along with new O-Rings and gaskets.
Four things I'd like to be sure you remember:
1. 134 DOES require a different oil (Ester/POE or PAG) than R12 (mineral). The old oil needs to be removed and replaced.
2. you use much less 134 than 12, start around 60% and work your way up watching high and low side pressures along with discharge vent temperature
3. if it has a sight glass, that was useful for R12 but is useless with 134. It will show streaks/bubbles when properly charged! Keep charging and it'll be overcharged. It'll lose performance and pop something on the high pressure side.
4. System should be labeled as retrofitted, equipped with retrofit service ports for a 134 gauge set, and a HPCO (high pressure cut off) switch installed to prevent release if the system goes over pressure. It stops the compressor.
God Bless, jd
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MN Ben
Minnesota
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I pushed the shop into getting it finished Thursday night, I pulled out of there at 7 pm. Otherwise he was going to have me bring it back on Monday. He was on his third day (and billed me for five hours).
I asked if he flushed out the mineral oil. He told me it does not need to be "flushed" and the conversion stuff will mix with the left over mineral oil and it will work just fine.
The hose ends leaked and apparently one of them started spaying R134 in his face. He stopped and replaced both of the hoses. I guess, as a few of you mentioned, the R134A can leak through smaller holes than the R12. It looked as if he used the same type of fittings for the new hoses they had new crimped sleeves on them. The o-rings were green.
He said he put in 3# of R134A and watched his gauges while he did it. I can see a bubble at the sight glass on the new dryer.
I did NOT see a label that the system had been retrofitted with R134A. I will ask him about that on Monday after work.
FYI. The shop specialized in AC and Radiators. They also advertise exhaust and total car care.
The AC measured 46.9* at the vents......I had to turn it off on the way home cuz it was so cold. I am satisfied other than the bill......I'm not gunna tell you. Lets just say I need to work 1-1/2 days of overtime to pay for it.
Ben
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Rex & Shirley
Bastrop, Texas
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Joined: 06/01/2004
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Ben, don't worry about the bubbles in the sight gage. That's one reason new systems don't have them as 134 and some other R12 replacements will always have bubbles when charged properly. Outlet temp is OK but nothing great and that happens with a 134 conversion SOMETIMES. Some a/c systems work like new and some never work right on the stuff.
Rex & Shirley S.
4 big dogs in a
Gulf Stream FriendShip
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Gale Hawkins
Murray, KY
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Joined: 07/22/2007
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Ben if you are cool that is about as good as you get. If the old hoses flexed at all on removing or reconnecting the results you reported would be very possible. He is correct about the mineral oil issue. In the old days getting the mineral oil out was a concern but not with the kits we have today based on my research and personal experience.
The key is to go to a professional shop like you did. After our radiator job I went to a profession shop so if there were any issues like you had so they could be correctly addressed and we start out on our trip knowing we did the best we could to insure the dash air was correct in every way.
The retro fit label is NOT important because the new charging connectors tell the COMPLETE story to any and everyone that would try to work on the system.
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