Should I add more refrigerant to my AC system?

The A/C system only does work (cool or reject heat), when it changes phases). In the evaporator the “Metering Device”, TXV (thermal expansion device), Capillary tube, or Piston, meters the refrigerant liquid into the evaporator. The pressure drop causes the liquid to change state to a vapor and enters at approx.. 80% liquid, and 20% vapor. The liquid needs to be boiling to a vapor the full length of the evaporator to be able to absorb as many BTU’s (British Thermal Units, the amount of heat required to raise one pound of water one degree Fahrenheit) as possible. This is where “Superheat” comes into play. They stop the boiling-off back up into the evaporator, which causes a loss of capacity, but ensures 100% vapor reaches the compressor. It IS a compressor, not a pump.

Once the low temperature, low pressure vapor enters the compressor it is compressed to a high pressure, high temperature vapor, that enters the “Condenser”. Since the ambient air is less than the temperature of the vapor, it starts condensing back into a liquid state. This is when the BTU’s of heat are rejected from the vapor. Now we have “SubCooling”, they stop the condensing phase a little back up into the condenser which causes a slight loss of capacity but “Subcools the liquid” to lower the temperature of the liquid entering the Expansion Device. And the cycle starts all over again.

Only during “Change of State (Phase)” does any work happen. You can pump it around the system all day and do no work. This is why it is SO important to have a clean evaporator and condenser coils. Any dirt, debris, or other blockages will lower the system’s capacity. But be careful not to bend the fins which will restrict airflow. An air conditioner is a “Dehumidifier” by design, and cooling is a byproduct. The lower the humidity the faster your skin evaporates moisture which is your body’s natural cooling system. This is the true basis for all air conditioning systems. So if you know anyone that is cold natured, have them put on a lot of lotion in the winter to slow down the evaporation process from their skin. And Yes, ALWAYS weigh in the charge for an accurate level, which will show up any system deficiency when you run it. Do not "Chase your Gauges"!

Failure2Comply

 

^^^^^^THIS^^^^^^

 

You are correct. The point that was trying to be made is that if the system.stopped cooling down the truck there is likely a leak that needs to be fixed first.

In regrds to repacing the dessecant pack you should not thave to replace the entire condensor on the truck. its a single tube like can that bilts to the condensor that you want to replace in addituon to the repair. The cehicle takes two 12oz cans of r-134a like you used (no stop leak or seal conditioner or any of that other crap)

Is the led in the ac switch blinking at you when you try to turn on the AC?

I may not be an expert, but i have certainly repaired and diagnosed a handful of auto AC systems and tge rental gauges from autozone along with the vaccum pump will certainly be good enough for any repair you need to do.

 

he didnt use a "suicide can".

 

It will.make your compressor work harder by cycling more ofteb than it should.

 

In the automotive world we call those DIY retard ac kits suicide cans. The term comes from the old days when the fittings were the same size and people would hook it up to the high side turning a tin can into a grenade but now the terms means death of an ac system.

 

All my dupount suva cans had the smile on the bottom......no issues))

 

agreed, but that doed not seem to be what he used based on his description.

 

My a/c works but maybe not quite as well as when it was new (2006). Can any local repair shop service the a/c to make it cooler or do I go to a specialist or dealer to get it done?

 

Nope the A/C light never blinked before I added the one can of refrigerant. It just wasn’t that cold. When the compressor cycled on and off, I felt a huge temperature variation in the vents.

Now after adding one can, it’s more cold and the temperature feels more consistent.

I’m still thinking of adding a little bit more and see how it goes.

 

dont overfill it! it wont help it cool much better (if at all) and can damage the system costing you lots of money) Either leave it as is or I would get the gauges and vaccum set from the autoparts place to put a full vacuum on the system test it for leaks and if its leak free then recharge it fully. That would be my reccomendation.

remeber the system takes 22 oz and while two cans is a total of 24 ounces remeber that one ounce of each can is oil so you will be good to go assuming the system is leak free.

 

In context for the above post its not hard to do.
1)rent manifold gauge set and vaccum pump from autoparts store.
2)purchase two cans of r134a refrigerant.

3) with engine off, pop hood, connect both side of gauge set to system. slowly open all the valves one side at a time to empty the system. (legally you should have a shop evacuate it but i wouldnt worry about it)

4) with all the valves open, attach the vaccum pump to the yellow hose, turn on the pump (ensure the pump has oil at the line in the sight glass) let the pump vaccum the system for about 30 minutes, close just the valves at the gauges, then turn off tbe pump. check to ensure you are holding negative 29.9 inches of mercury on the gauge....give it another 30min to ensure hou dont have a leak. if you have a leak the gauge will go back to zero, at which point you will have to find the leak, repair it, replace the dessicant and repeat test.

5) if the system stays at neg 29.9 inches of mercury, than you may attach the yellow hose to a can of refrigerant, dont puncture the can yet.

6) start truck, ac on full blast, windows down, thermometer in dash vent.

7) with yellow hose attached to can screw invalve to puncture, than slowly back out to release refrigerant, purge the hose at the valve on the gauge set at the yellow hose.

8) slowly, open only the low (blue) side valve allowing refrigerant into the system.

the compressor will kick on and start taking refrigerant. the can will get cold so shake it and have a warm damp towel to wrapped around to hold it.

9) when firstcan is done, close the low valve on the manifold again, then put the second can on the yellow hose, again punture and slowly allow refrigerant into the yellow hose. purge the yellow line again.


10) open low side valve on gauge set again allowing refrigerant into system.

11) check temperature on thermometer when second can seems empty with windows down and ac still on max blast. you shoykd be getting cold air by now likely in the 50s depending on environmentals.

12) when second can is done and you have cold air. close all valves espicially the ones that attach to the lines.

13) with all valves closed slowly remove second can and manifold gauge set from vehicle, double check your schrader valves on the ac lines are not leaking and replace dust caps.

14) cleanup and return tools for deposit.

stay cool.

 

The can will say if there is oil added. A can of just R134A will just have... R134A in it.

 

I have never seen a 12 oz can that didn't have some oil in it. Regardless between purging the lines and just the amount of gas that will be in the manifold lines he will be gtg using 2 cans.

 

Yesterday I added more refrigerant on top of what I added 2 weeks ago.

1. 75°F ambient temperature.
2. I added more until the low side read 30psi and high side read 200 psi.
3. I added more refrigerant in 10 second intervals. I kept adding more but stopped after the last 3 times when the pressures stopped rising. I figured I should stop before I screw something up. It seems like I used half a can this time.
4. The temperature at the vents were still at 44°F but the compressor seems to stay on much longer (60 seconds on / 5 seconds off). The temperature feels much more consistent now. However it still doesn't seem as cold as few years ago.

I have a question:
1. When I removed the schrader valve caps, I heard a slight hiss. Does that mean the schrader valves are leaking?
2. Is there any tricks to replace the schrader valves without losing the refrigerant?

 

Event though the can I used is pure r134a, there is still neon green residue left on the hoses fittings after I take apart the manifold gauge. The neon green substance seems oily so I don't know if it's just leak detection dye or just some normal compressor oil.

 

There is a special tool for removing Schrader valve cores, also look on utube


https://www.amazon.com/schrader-valve-removal-tool/s?k=schrader+valve+removal+tool

 

When it comes to ac its best do have it done right. With one of those ac manifold guages. Those cans you get at auto zone do more harm then good.

 

Crap, and I just bought this:


Now I’m thinking about returning it....

 

Thanks!