A/C rebuild tips

Falcon20x

Registered User
I’m by no means an expert, but I thought I would share my experience, tips and tricks in a successful AC system rebuild.

With the right tools and a little research fixing the system is easy to do, but you need to take your time.

1. Watch all the videos in this thread
http://www.youtube.com/watch?v=0DXAiQbqWmk (fast forward through the first minute)
image.jpeg
2. Before to do anything with the system, properly remove the old R12 refrigerant (check with your local shop).

3. DO NOT SKIP THIS STEP: You need to get the old oil and/or any contamination and debris out of the system. Flush the evaporator, the discharge line, liquid line, and the condenser if you are going to keep them. Set your compressor at 40 PSI for this step
http://www.youtube.com/watch?v=TeqhOqK1TNA
http://www.youtube.com/watch?v=Lnu8hA9F9S4

Warning: No one really tells you about this, but the flushing agent usually evaporates quickly unless it is mixed with oil. The evaporator and the condenser both contain several ounces of oil, both will need a large amount of flush agent to push the oil out (the amount of one flush kit bottle each).
Once you flushed the evaporator and the condenser (40 PSI), you MUST dry out the system. Ideally you should use nitrogen for this, otherwise use compressed air with the pressure set at 80 PSI. Make sure you have good filter in line to remove the moisture from the compressed air. Let the air flow through the components for at least 30 minutes. Doing this will ensure that you have clean and dry component.
If you chose to install a new one, keep in mind that the evaporator is permanently glued into the HVAC housing and will require dash removal to even get close to it.

4. Install the components. (Do not hook them up yet, make sure they all fit)

a. Start with the liquid line. (Remember to add oil all the O-rings)

TIP: On the Thunderbird SC, the orifice tube is build into the liquid line, it must be cut out to be replaced.
A new orifice tube and the necessary kit required for doing the job cost as much as a new liquid line. Unless you live in a extremely hot region and you want the optional automatic adjusting orifice tube (+105 degrees), I recommend that you get a new liquid line with a build in orifice tube.
image.jpg
Orifice tube Kit $19.88
http://www.rockauto.com/catalog/moreinfo.php?pk=815395&cc=1140387
Orifice tube with automatic adjusting $ 27.79
http://www.rockauto.com/catalog/moreinfo.php?pk=869809&cc=1140387
Liquid line with build in orifice tube $19.99
http://www.rockauto.com/catalog/moreinfo.php?pk=818385&cc=1140387


b. The refrigerant hose assembly/suction line. ( low side, blue side on the pressure gage manifold)

Remember to oil all the O-rings
http://www.rockauto.com/catalog/moreinfo.php?pk=818258&cc=1140387
This is a good time to install the R12 to R 134 conversion kit. Use the small valve screwdriver to remove the valve on the hose.


c. The compressor:

Do not forget to add oil (watch the video http://www.youtube.com/watch?v=0DXAiQbqWmk).

The manual says the thunderbird SC A/C system requires a oil charge of 7 ounces. The compressor should have between 3 to 5 ounces. In addition, you should add 3 ounces in the evaporator, 1 ounce in the condenser and 1 ounce in the accumulator.
My compressor came prefilled with 6.75 ounces of PAG 46. Make sure you use the same oil in the entire system. I drained 1 ounce from the compressor, added 0.75 ounces and pour it into the drier.

Do not forget to verify the air gap. Mine was set at the factory.

d. Drier/accumulator: (as shown in the video do not forget to add oil to it)

Do not remove the plastic caps until you are ready to install it
http://www.rockauto.com/catalog/moreinfo.php?pk=3908418&cc=1140387
The replacement drier elbows angle is slightly different, but it will fit.


Warning: DO NOT SKIP this one.
When attaching all the components together ensure that all the spring locks are engaged. The drier to evaporator spring lock may appear to be in the lock position, using a mirror to look from the back forward is the only way to ensure that it is properly locked. Do not assume it is otherwise you are taking the risk to have the hose rupture under the pressure. I had to found out the hard way.
image.jpegimage.jpg
5. Vacuum out the system (time line 7:10) but first rotate the compressor 10 turns as shown on the video (time line 6:35).
Keep in mind that not all vacuum pumps are equal. If you have the choice, the higher rating/ CFM, the better. Auto zone will loan you a pump with 2 CFM rating
http://www.youtube.com/watch?v=0DXAiQbqWmk

6. Recharge the system: Do not add more than 90 % of the original R 12 charge.
The Thunderbird SC AC system takes 40 ounces +/_ 2 ounces of R12 Freon.
90% = 36 ounces= 2lb of Freon.
Autozone and O'reilly, both have their own brand of freon 12 O.Z. cans. For a brand new system it is as good as the expensive other brand.
Unfortunately, even with the manifold valve closed, every time you swap a can you will be opening the line letting a little bit of air in it. Once you are sure that your system is leak free (holds the vacuum), you may ask your local shop to vacuum your system again ( 45 minutes) with their pump (better CFM rating) and do this step for you. I did it myself and it still worked out though.

http://www.youtube.com/watch?v=lglPJuBXVeE


Specific Tools needed:

• Vacuum pump (can be rented from Autozone via their free loaner program)
• A/C Flush kit (can be rented from Autozone via their free loaner program) You will also need to get a female air chuck to hook up the bottle to the compressor.
• A/C gauges (can be rented from Autozone via their free loaner program)
• Valve screw driver (You will need this tool to replace the R 12 valve on the low side line with the R 134 adapter.( http://www.banggood.com/Valve-Core-...ndustrial-us&gclid=CJ3roo2yn78CFQIT7AodpjYALg)
• R134 conversion kit
http://www.ebay.com/itm/New-A-C-Sys...Parts_Accessories&hash=item20dace044f&vxp=mtr
• High capacity air compressor
• AC can tap adapter http://www.amazon.com/R-134a-R-134-Refrigerant-Dispensing-Thread/dp/B00EU1108G



Items requiring replacement:

Drier/ Accumulator:
Orifice tube: http://www.rockauto.com/catalog/moreinfo.php?pk=818385&cc=1140387


Recommend replacement for optimum performance:

• Compressor: The FX 15 compressors are prone to failure, it is only a mater of time before it goes. If you have a original FX 15 compressor you should replace it with a FS 10 compressor.
I recommend buying the kit
http://www.rockauto.com/catalog/moreinfo.php?pk=5242185&cc=1140387
http://www.rockauto.com/catalog/moreinfo.php?pk=3928476&cc=1140387

• Condenser: The cost and time to flush old parts vs the price of a new one was not worth it to me.
http://www.rockauto.com/catalog/moreinfo.php?pk=3612027&cc=1140387

• Liquid line: see comments above.
• Clutch cycling climate control Pressure switch( located on the dryer/ accumulator): The R 12 pressure switch has a higher pressure setting (OFF pressure: 25 PSI/ on pressure: 45 PSI) then R134 (( off pressure 21 PSI/ on pressure 42 PSI).
http://www.oreillyauto.com/site/c/d...ck=Search_01957_1140387_-1&pt=01957&ppt=C0053

TIP
The clutch cycling pressure switch is another thing that most shops won't do or tell you about for the conversion. If you got this far just spend the $25!



http://www.youtube.com/watch?v=0DXAiQbqWmk

Compressor kit: $ 157.79 ( includes: the o-rings, drier and compressor
Liquid line:$19.99
Condensor: $ 82.79 (you do not have to get a new one)
Refrigerant: $ 36
R12 to R134 conversion kit $7.90
Refrigerant hose assembly( suction line): $89.99 you do not have to get a new one)
Clutch cycling pressure switch: $25.90
Special screw driver: $ 1.90

Total is from -/+ $250 to $424 depending how much you want to do.


After paying $180 at a local shop to convert my A/C system from R12 to R134 the technician told me that my compressor had failed and they will need a additional $400 in labor + parts to finish the job. No need to say what end up doing.
 

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a few more picures
FS 10 compressor
IMG_1615.jpg
required chuck to connect the flush bottle to the compressor
IMG_1620.jpg

spring lock check
IMG_1626.jpg
IMG_1627.jpg

I had to do a lot of research to find the little tips that no one really tells you about, I never found one place with a A to B explanation including the little gotchas. This is by no mean the complete story so feel free to make any suggestions or corrections.
 
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Thanks for the information! I am planning a rebuild later this summer. As soon as possible, really. I already have most of my parts and supplies bought. I will compare my notes to this thread in more detail before I start. Thanks!
 
I thoroughly endorse this thread. On a car 20+ years old it is a minor investment to replace the entire system before suffering a big failure, or replacing it one part at a time, paying to R&R the refrigerate each time. A properly working AC system is a great thing.

The only thing I have to add is to mention that replacing the evaporator is no fun which is another reason why being proactive is the best policy. The evaporator is permanently glued into the HVAC housing and will require dash removal to even get close to it.

Great post!
 
I agree with all of this also. Having work on a/c systems for the past 35 years, the only thing I would do differently is use nitrogen to blow out the evap or anything else. Compressed air no matter how good the air dryer system is, still has moisture in it. Nitrogen dosen't. I carry some in my truck for that reason, and for a very low pressure purge when doing any brazing on systems to prevent scaling on the inside of system. Very few air dryers can get down to a very low dew points. Low as -15degree f.
 
I agree with all of this also. Having work on a/c systems for the past 35 years, the only thing I would do differently is use nitrogen to blow out the evap or anything else. Compressed air no matter how good the air dryer system is, still has moisture in it. Nitrogen dosen't. I carry some in my truck for that reason, and for a very low pressure purge when doing any brazing on systems to prevent scaling on the inside of system. Very few air dryers can get down to a very low dew points. Low as -15degree f.

I did read about that, (I think it is also in one of the videos). It is highly recommended, but unfortunately I did have that option. I will add it to the original post.
Thx
 
I thoroughly endorse this thread. On a car 20+ years old it is a minor investment to replace the entire system before suffering a big failure, or replacing it one part at a time, paying to R&R the refrigerate each time. A properly working AC system is a great thing.

The only thing I have to add is to mention that replacing the evaporator is no fun which is another reason why being proactive is the best policy. The evaporator is permanently glued into the HVAC housing and will require dash removal to even get close to it.

Great post!

Thank you for your support!
The reason mentioned above is why the evaporator is the only component I did not change. I will update the post.
 
Excellent write up, thanks.

I'd add that doing all this work while the system is open is a great opportunity to change the condenser to a narrow width, parallel flow unit.
 
Thank you for your support!
The reason mentioned above is why the evaporator is the only component I did not change. I will update the post.
I've done this more than once and Im an expert at it.. and I'd say this much "if it aint broke..." ;)
 
Whats the deal with the pressure switch. I am finding conflicting information about using the r134 switch versus the original style r12 switch
 
Whats the deal with the pressure switch. I am finding conflicting information about using the r134 switch versus the original style r12 switch


I found the original spec'd switch to be obsoleted with the new one servicing across the board. I was running 134a with the R12 switch and saw no cooling issues, but the compressor cycled more frequently that it should have...a new 134a switch cured that.
 
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Technically, if you use the R12-calibrated switch with R134a, the system won't cool as well at max as the proper switch will allow it to, since it will trigger off at a higher pressure (R12's higher than R134a - or is it the other way around?)

PRACTICALLY, I'd wait to swap until you needed to (as in switch quit working).

RwP
 
is there an alternative part number for the switch? I found the version for r12. The r134 switch at oriellys was ridiculous with shipping and there is not an option to ship it to the store. Anyone know of a part number for advanced, autozone, or rockauto?
 
O'Reilly Murray 36676 $21.99
UPC: 96361366763
R134a
System Mounted Cycling Pressure Switch
Off Pressure (psi): 21 psi
On Pressure (psi): 42 psi

Napa 207887 - same specs & similar price.
 
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Updated the original post with all the inputs I received.
I also added some comments regarding the vacuum pump CFM rating.
 
is there an alternative part number for the switch? I found the version for r12. The r134 switch at oriellys was ridiculous with shipping and there is not an option to ship it to the store. Anyone know of a part number for advanced, autozone, or rockauto?
If you guys have a set of charging guages, you can adjust the r12 switch to cycle lower by peeking inside and turning the set screw (start with about 1/8 turn CCW).. watch low side cycling pressure and if/when you get it to about 20 psi :eek: you should be at minimum core temp. Any lower and you'll probably have freeze up. Charge the high side to about 3x ambient temp (yes.. thats right.. on a 100 degree day.. you'll see over 300psi). I live in Texas and this is how you do it to get 34 out the center vent on a 100 degree day.. ;) Needless to say your condenser needs to be the newer design AND.. your fan must operate properly. :cool:
 
If you guys have a set of charging guages, you can adjust the r12 switch to cycle lower...

Yes, that's possible on ones with the screw under the connector & a good tip - just be sure to remove it and check/replace an old o-ring with one that is HNBR compatible. A new 134a switch should come with the right one.
 
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Orifice tube

Timing is everything , I just did the orifice tube mod. & compressor replacement. I have done the low press switch adjustments before & it's easy.
 

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