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Changing out whole AC system

mazda626awd on Thu May 16, 2013 3:49 PM User is offline

Year: 1991
Make: Mazda
Model: 626
Engine Size: 2.2
Refrigerant Type: R 12
Country of Origin: United States

My 91 Mazda 626 R 12 system has a blockage and I decided since I got to open it up, I might as well change what I can't effectively flush and convert it to 134A. I bought a new compressor, condenser, receiver/dryer, TXV and ordering the evaporator and flex lines. I also bought a vacuum pump, Charging manifold gage set that has adapters for both R12 and 134. I got an empty 30 LB bottle w/2 valves so that I can recover the R12 to possibly use it in my large fleet of R12 cars. One question is, how do I make sure my empty tank is clean enough to use for recovery and reuse? When I remove the old system, is it better to reuse the flex lines since they have been subjected to R12 for over 250K miles and are less likely to seep the 134A? When I find somebody with a recovery machine, will that system filter the R12? Are there caps and plugs available to use on the system components after I flush them? I understand that I have to flush everything with a solution compatable with the 134 that I will charge with, and I need to measure the R12 mineral oil drained from the system and use nearly the same amount of PAG oil in the new system. If anybody has some guidance for me, I'd greatly appreciate it. I'm trying to learn AC as I go. I've read alot but lack hands on experience.

WyrTwister on Tue May 28, 2013 12:33 PM User is offlineView users profile

I think barrier lines are made , for R134a , but do not know for your vehicle ?

As far as how much oil , I would look up / research how much goes into the compressor and the total for the system . Then subtract , to see how much to put into the accumulator .

Where is the blockage ? The expansion valve ?

Did the old compressor thrash / self destruct ?

God bless

Edited: Tue May 28, 2013 at 12:37 PM by WyrTwister

mazda626awd on Thu May 30, 2013 3:06 PM User is offline

mazda626awd on Thu May 30, 2013 3:24 PM User is offline

Thanks for the response WyrTwister, Sounds like a title for a safty wire technician from my Navy days. Anyway, it seems the blockage is at the TXV most likely. It was suggested I tap on the thing. Not an easy endeavor. I can't get the fan housing out and not enough clearance to get a good shoot at the valve. I'll more likely have to recover the R12 and remove the lines from the evaporator to get to it, at that point it only makes sense to follow my plan and replace all I can't flush and convert to 134. I'd like an input on how to make sure my recovery tank is clean and usable to store the recovered R12 for future use on my other R12 systems that seem to be working. I talked with a ASE that told me there will be seepage whether I reuse my old lines or buy new lines made for that car. Although I read somewhere that the used lines may seep less due the years of freon exposure preameating the interior.

iceman2555 on Thu May 30, 2013 6:47 PM User is offlineView users profile

A suggestion would be to stay with R12 for this vehicle. Unless you intend to change the condenser to a more efficient model, it is doubtful that you will be pleased with the performance of this retro.
All hoses today are make of 'barrier' type material. I know of no one that pulls rubber lined hoses at this time. Of course, if some NOS parts are utilized, then the hoses could be rubber lined and if so, they tend to 'seep' 134a due to the smaller molecular structure of 134a.

What ever you sure to maintain the manifold from your OE compressor....most aftermarket units require the use of the old manifold.

Simply 'recovering' refrigerant into a 30 lb can does not mean you will be able to recover your total refrigerant charge and it will not be cleaned enough to reuse.

Good luck

The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

mazda626awd on Wed June 05, 2013 1:52 PM User is offline

Thanks iceman, I would love to stick with the R12 but its almost impossible to get around here as I'm sure at most places.

I already bought a condenser from Advance and noticed it was slightly smaller all around than OEM. Is there a way to find a suitable replacement that will make the 134 conversion less disappointing?

Is the condenser the only piece of the picture that needs to be increased in size or is the evaporator a problem as well?

What are the pros and cons on flushing the evaporator? I was told that its no problem, but I was under the impression that it fell under the same flow restrictions as the condenser when it came to effective flushing. Should all flushing be done with a pulsing unit?

None of these recovery machines clean the freon enough for reuse? The AirGas Co. near here doesn't have an exchange program I'm told for the R12. What are others doing that decide to stay with R12?

apexair on Mon June 17, 2013 6:52 AM User is offlineView users profile

Potentially one of the most costly auto A/C repairs is when you have to replace the A/C compressor. If you're facing that situation now, it's really important that you understand all the steps that must be followed in order to do the job properly and get warranty on your replacement compressor. Keep in mind that , we talk about apply to either new or remanufactured compressors, so there is no difference.
1) the condenser
2) the accumulator or receive drier
3) refrigerant or compressor oil
4) orifice tube or expansion valve (also called a TXV)
5) hose or line assemblies
6) Before you finish, you must flush the A/C system.
You should also give serious consideration to having an in-line filter installed.

Apexair provides you with a variety of home air conditioners with stylish, sophisticated design

mazda626awd on Wed June 19, 2013 11:39 AM User is offline

Thanks apexair, I've been doing a lot of research in general. One of the things that does sound good is that inline filter. Question, Where to install it? And if it needs changing you have to evac the system. I've read about tools that let you replace shrader valves without disturbing the charge, how about an inline filter that will do the same thing?

I'm still somewhat undecided as whether I'll convert to 134. I'm still looking for a way to recover my R12 into my empty 30 lb. Tank. Can a recover,recycle,recharge machine recover the R12 into its onboard tank than recharge it into the external tank?

Dave in VA.

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