Keys To Adding Refrigerant ?

Joined
Sep 10, 2010
Messages
3,497
Location
GA.
What are your keys to adding the typical 134A refrigerant to your vehicle (i.e do's & don'ts) ?
My A/C starts out trending a little warm , then cycles slightly warm / cool before turning eventually all cool .
Vehicle is a 2017 and never has had the refrigerant checked ... Thanks in advance !
 
Joined
Jan 22, 2011
Messages
7,580
Connect a set of gauges to both sides of the system, otherwise you are just guessing. Fix the leak first, then evacuate, check to see that the system holds vacuum and then add refridgerant matching the capacity specified for your system..
 
Joined
Jun 2, 2002
Messages
3,510
Location
Georgia/Retired
If you're a DIY'er and not equipped with the equipment to recover refrigerant or want to pay the fees for a garage to use their equipment then there really isn't much you can do other than just hooking a hose up to the low pressure side of the system and adding some refrigerant until it blows cold.

I do suggest you buy a set of cheapy gauges from Harbor Freight and get a reading from both sides of the system just for informational purposes. A gauge set will help diagnose the system by letting you know how the high and low side are in relation to each other while the system is running. Also, you can add refrigerant through the low pressure side while the gauge set is hooked up and you have the ability to purge the refrigerant line of air before introducing the refrigerant into the system. Moisture is your enemy and warm, humid, Georgia air is the worst kind of enemy.

So, get a gauge set, see if your system seems to be in proper working order by monitoring the pressures while it's running, and add a bit of refrigerant through the gauge set until things read properly.

A/C work is tricky in the sense that pressures and performance are completely dependent on the ambient air temperature and humidity. Professionals that do this stuff know what they're looking for on the gauge set and tend to provide a better outcome than someone like myself who does A/C work when I have to just to keep the wife happy. My only tidbit of advice is to not introduce moisture into the system while you're topping it off and wear your PPE (personal protective equipment).
 
Joined
May 30, 2010
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15,379
Location
North Carolina
Flush the air out of the gauge/ line with refrigerant before connecting to the low pressure side. Otherwise you are introducing air and moisture every time to make a connection.
 
Joined
Apr 12, 2021
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42
Do: Understand principles of operation and components before proceeding, including the high and low side pressures, system capacity, oil type/capacity for your car; possess the proper tools (vacuum pump, manifold gauges, kitchen scale); consult a professional as required

Don't: "Top off" for the heck of it - especially with those one-shot cans shown on TV (primarily being used by effeminate men who have no idea what they're doing).

Joking aside, I bought all the right tools about 10 years ago after getting tired of relying on shops for everything related to A/C...and that was a real pain with 5-6 cars and living in TX and AZ.

Get smart...get the tools...and do it all yourself.

In response to your specific issue, have you checked your blend door operation? Sounds like you may have a sticky or binding blend door or a blend door motor on its way out...
 
Joined
Jun 5, 2003
Messages
25,550
Location
Apple Valley, California
The proper way is by starting with a vacuum and add it using a scale. If using r134a it can be some weird stuff and going by pressure only won't always work.

I'm not familiar with the new 1234 refrigerant to comment on it.
 
Joined
Jun 13, 2013
Messages
2,786
Location
Virginia
As the system is working, (but not very well), there is no need to drain it, pull a vacuum, then refill.

The system has pressure, just not enough…

Step 1: Fill valves. Get some dish soap, and water. Use either a spray bottle or small paintbrush to put soap/water mix over the R134a valves. Look for leaks.
Very common to have pin leaks here. Valves can be replaced without draining the system, but requires a special tool…
Aupoko R134A Valve Core Quick Remover Installer, High Low Pressure Valve Core Remover Tools Kit for R13A Refrigerant Air Conditioner System
https://a.co/d/gKX7Hn9

Step 2: Get a bucket filled with lukewarm water, a can tap, and a R134a PAG oil charge…
Not a can of freon, a can of oil. Only do this ONCE in the life of the car, or you will drown the system…
Super Tech R-134a PAG Oil Charge Refrigerant, 3 oz.
https://www.walmart.com/ip/337218764

Add to A/C system…
Use lukewarm water to keep can from freezing…

I like the A/C Pros Oil Charge, 2 ounces freon, 2 ounces oil, and 2 ounces “Ice 32 Performance Enhancer”…
 
Last edited:
Joined
Jul 29, 2022
Messages
127
Location
Arizona
When I had my 2010 Honda Civic that had a slight refrigerant leak I used a manifold set while referencing the service manual.

The service manual had a pressure check procedure (open glovebox, max AC, RPMs at 2000, all doors open, etc.). I referenced the output temperature & low/high side pressure with the ambient temperature & humidity (chart provided by Honda) and was able to restore performance. I opted to go a little on the low side just to play it safe.
 
Joined
Sep 6, 2007
Messages
2,146
Location
TX, USA
That awfully sounds like any AC in the south when temperature are above 90F and high humidity.
IMO, I would just leave it alone.
All you need is to check the pressure, if you have the knowledge and tool to do it.\
If it is low, then add. Otherwise, that is a quirk.
R-134 is very finicky, you cannot have too much as mentioned above.
 
Joined
May 18, 2012
Messages
7,555
Location
Baltimore, Maryland, USA
You should be able to get close enough by adding the appropriate amounts with and a scale, but I also recommend to use a gauge in the center vent and monitor the temperature and stop adding refrigerant when the temperature starts to go up.
 
Joined
Jan 2, 2004
Messages
9,788
Location
California
Gauges, check pressures. IIRC, low side is around 30-40psi, high side is 150-160psi at idle and ambient temp.

Purge the charge line(yellow) before adding refrigerant. Use virgin R-134a/R-1234yf ONLY. No AC Pro, no Arctic Chill.
 
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