A/C Question

[NJTB]

On my way back from Utah, the A/C started to blow cool, but not cold. It wasn't bad enough to worry too much about it, but figured I'd look into it. Got a new orifice tube and 2 14 ounce cans of R134 freon. Replaced the orifice tube (there was nothing on it) and pumped it down to 30" of vacuum for about 1/2 hour.
Closed the valves for about 10 minutes, vacuum held, so I was pretty confident there was no leaks.
The A/C charge for this says 1.85 lbs. (29.6 ozs.). Hooked up the first can and shot it in as a liquid ( can upside down, ignition off) on the high side, took the whole can no problem. On the second can, I put it in as a vapor with the car started, and it took FOREVER to get the whole can in, probably 45 minutes. Finally aggrivated me, and I jumped the switch at the accumulator so the compressor ran all the time.
Because the can was warm, I knew the freon wasn't going in to the system. The hi side pressure was 190, low side 40. The freon should have been flowing, as I'm pretty sure the pressure in the can was greater than 40.
Then, just like that, the can got cold and went in.
So I'm wondering, is this some crazy thing I don't know about with the TB A/C? Like it won't turn on unless the blower is on?
Just for the truly anal retentive on this list, while it was pumping down, I took the grill off and cleaned the bugs out of the condenser. There were plenty of them.
I also wondered about the fan clutch, but no, it was good.
Ever happened to anyone else here?

 

[mrrsm]

Just a few recommendations for others "Tuning Up" their Low R134A circumstances:

(1) Always use the BLUE (Low Pressure Line) as the "Port Of Choice" for re-filling a cleaned/vacuumed HVAC system as a VAPOR. The reason for this is because ALL LIQUIDS are Incompressible and introducing Liquid Freon into the System by inverting the Can can allow Straight Freon to enter the Compressor and risk damaging the Scroll Compressor Internals.

(2) A/C Compressors are designed to compress VAPOR ONLY .. NOT Liquids. The presence of the Accumulator acts like a "Temporary Storage Tank" so that any collected Liquid Freon will be able to sit inside there just long enough to vaporize again before it gets pulled right back int the Low Side Inlet Port of the A/C Compressor.

(3) If TOO Much Liquid Freon is allowed into the Accumulator by Up-Ending the Can...it might cause an overflow into the Low Side Line and "Slug The Compressor". Again... By holding the Can between the 12:00 and 3:00 O'clock Positions and gently shaking it back and forth, this helps in Vaporizing the Liquid Freon and coax it into the Low Side Line. As the Freon evaporates and enters the System... it will steal ambient heat from the atmosphere around the can and "Frost Up". You can accelerate this vaporizing event by slightly warming the Can just a bit with Gloved Hands.

(4) It generally takes around 10 Minutes for a Fresh Charge of R-134A to completely distribute itself throughout the A/C System and normalize in places where it should be returning to the Compressor as a Super-Heated Vapor... then traveling through the Compressor and into the Condensing Coils and converted into a Hot Liquid during "Sub-Cooling". The Electro-Viscous Fan along with having Clean A/C Condenser Coils and a Topped Off Radiator helps to eliminate this trapped heat as much as possible.

(5) Introducing Liquid Freon directly into the High Side (RED) Liquid Line from Cans of R-134A is Very Dangerous. If the can Ruptures and Explodes, getting splashed with Super Cold Freon in the Eyes and other exposed skin is not worth the Risk for the sake of speeding things up. This is why ALL R-134A Cans of Liquid Freon ONLY come with Low Side Port Connections and Hardware.

(6) The Last Suggestion is to take the time to Flush Out the A/C Lines, Evaporator AND Condenser Coils using Liquid Flush poured into an inexpensive Aluminum Flush Cylinder propelled by Compressed Air at Low Pressure. Afterwards, if you have the proper Dry Nitrogen High Pressure Tank and Proper Low Pressure Regulator available, you can more thoroughly eliminate any blockages of Dirt, Contaminants or Old PAG 46 Oil that can obstruct the Flow of the Freon as a Liquid and a Gas and completely id of the system of any residual AC Flush. All of these actions should ONLY be taken AFTER removing the Lines from the Old Compressor FIRST to avoid driving more contaminants Deeper into the A/C System. Do NOT Flush out a Brand New Compressor. Replace the Used Vacuum Oil in your 2.5+ CFPM A/C Vacuum Pump prior to pulling a Deep Vacuum on the system.

Here is where to find these items on Amazon.

Amazon.com : a/c flush kit for automotive

www.amazon.com

 

[aaserv]

The needle valve on cars can be finicky... Ive hooked up hoses to them and had to tighten them just another hair or even loosen them sometimes before the gauge hose activated the needle valve. Kinda sounds like what may have happened to you....

 

[NJTB]

@MRRSM
I was taught, way back in the day, it was ok to charge liquid on the hi side engine off. Wait a few minutes, start the car, and finish with vapor on the low side. Did something change over the years?
@aaserv
Yes, I screwed around with those needle valves for a while as I thought that's where the problem was but wasn't sure. It surprised me it all of a sudden it started to work.

 

[mrrsm]

NP... for you... However, this is just a Safety Suggestion for the Uninformed Readers-Thread Followers who might interpret your method as a generally accepted Auto HVAC Charging Practice. Using a Three Port A/C Gauge Manifold can sometimes even get confusing for the Experts, let alone the Average User who just bought one at HF and needs to "Quickly' Charge up the SUV A/C System with 1.something Cans of R-134A.

The Boiling Point of R-134A at Sea Level Atmospheric Pressure is −15.34 °F...and when mixed in pressurized concentrations with Air becomes Flammable. The Danger of Frostbite or Eye Damage from sudden exposure from a Burst Can is not trivial.

The difference here is the distinction between whether something Mechanical CAN be Done... versus whether or not it SHOULD be Done. Again... For others... Please View this entire Video as a General Auto A/C Re-Charging Instructional and focus in particular at 10:14 for the explanation of why Adding R-134A from Pressurized 1 Lb Cans should ONLY be done on the Low Side Port:

 

[Mooseman]

So I'm wondering, is this some crazy thing I don't know about with the TB A/C? Like it won't turn on unless the blower is on?

Yes. The blower must be on for the A/C compressor to work. Most vehicles behave this way, the ones with manual systems anyway. When filling the system, you should have the blower on hi.

 

[Mektek]

The way I've always done it is to charge the low side with the can submerged in a container of hot water. If there is a vacuum then open the valve first to so the system isn't empty on startup and most of the first can will go in. Then start the AC on high and it will empty the can.
Disconnect the can, replace the hot water and do the same for the second can.
Also, a good tip is to purge the lines before connecting to the system - open the can valve slightly so that there is a slight hiss while connecting. This will blow the air out of the lines and fill valve.

 

[TJBaker57]

Now this will go contrary to recommendations for sure, but if you are measuring in the charge and trying to get that last few ounces in..... jump the compressor and turn the blower to the minimum setting. NOT the high setting. WHY?? Doing this will lower the evaporator temperature since you are not flowing the warm air over it. This in turn will lower the entire system pressure. So instead of flowing into the low side system pressure of 40 or 50 psi you are flowing in against maybe half that pressure. Thus the can pressure vs low side system pressure is greater.

Warming the can helps as well but it keep it in reasonable. No boiling water, if you can't keep your hand in the water it's too hot.

This approach is NOT for evaluating system charge but ONLY for helping to get the full charge in when you KNOW the amount to be added.

An Edit: I didn't mention this but in the photo it can be seen that I do have a high side pressure gauge connected, in addition to the Torque Pro app. NEVER jump a compressor for more that a moments test unless you are closely monitoring the high side pressure. Ever witness a high pressure relief valve activate?? That will get your attention !!

 

[NJTB]

@Mooseman
I figured the blower has to be on for the A/C to operate about 5 years after I owned the car. When it first happened I was pretty perplexed but figured it out.
@TJBaker57
Yes, I had hi and low side guages hooked up, hi side never went over 190. I'm very careful of that kind of stuff.
@MRRSM
I watched the video you posted from Chris Fixit and was pretty surprised he added liquid (turned can upside down) on the low side. Rule of thumb for me was liquid on the hi side (before the orifice tube) and vapor on the low side. It worked for him so I guess it's good.
Right now I'm chalking it up to shit cans of freon (got them at WalMart) or the valves that pierce the cans.
It's blowing cold now, no unusual noises, wifes happy, all's good.
Thanks to all that replied.

 

[JerryIrons]

NJTB did you watch the end of the compressor, where the belt and clutch are, while the engine is running? If it engages and turns that means the compressor is running and the system should be working. It will usually cycle on, run for a bit, and cycle off for a bit. Sometimes that clutch gets loose and doesn't engage, I've knocked it with a 1x2 of wood to jar it and suddenly you have AC.

The specs are in the service manual, telling you exactly what your high and low pressures should be at given ambient temperatures and humidity.

You can run your engine at 2000 rpm, this will get the AC system working better and also move that refrigerant from your can into the low side port better.

Personally, I would not be touching the high side ports adding refrigerant. It's easy enough to do via the low side, although maybe it takes longer, and you can avoid dealing with things going sideways with high pressure, as in 350 psi...

Also sometimes leaks aren't as easy to fund under vacuum, but you can under pressure. I made an adapter and have put pressure on the system with my air compressor, finding the hissssss makes it easy.

 

[TJBaker57]

I made an adapter and have put pressure on the system with my air compressor, finding the hissssss makes it easy.

This should never be done. To do a pressure test only bottled compressed dry nitrogen should be used and sometimes a small amount of R134a is added if using a sniffer type leak detector.

Compressed air is heavily laden with moisture which will likely contaminate the system and can lead to early failure.

 

[mrrsm]

Not to drag out this issue too much more ... But when ChrisFixx adds in that last small amount of Liquid R-134A , he did so when the can was almost empty. He was also introducing it into the Accumulator with the HVAC Manifold Gauge Sight Glass showing the residual material almost instantly Evaporating.

This is not the same thing as if he were Dumping in Full Can(s) into the System... which was undercharged at the time of his actions and having the Compressor starting naturally as the Low Side Switch engaged correctly around 40 PSI. Jumping the Compressor to get it to pump in the absence of having the PAG 46 Oil and Low Side Gas completely distributed around the System can invite an Early Death to the Compressor. Inducing 2 Ounces in the Accumulator, 2 Ounces into the Compressor and 2 Ounces into the Condenser Coils is the Rule of Thumb.

The main point here though is that staying away from doing anything on the High Side is considered "Best Practices" in the Automotive Industry. We Love You, Man... so we add these suggestions and inputs in order to look out for EVERYONE who may encounter these situations and hope they too will do the A/C Repair work as safely as it can be done.

 

[JerryIrons]

What exactly do you think happens to an AC system when a leak occurs, and the system completely depressurizes and lets in atmospheric air through the leak? On a hot humid day? For months on end?

Give me a break. A little bit of compressed air pumping your system up for a short period to find a leak, followed by a vacuum pump to empty out the system is not going to be the hiroshima that all your large typing predicts.

 

[mrrsm]

Perhaps... but almost as soon as you begin pumping down the System...the hopefully New Vacuum Oil in the Vacuum Pump will become overly contaminated with moisture from compressed air that is REALLY saturated with H2O. The danger to the System is that Water mixes with CFC and HCFC and very quickly forms Hydro-Fluoric Acid that will rapidly attack the Coil Windings inside of the Compressor. Fluorine is the most Chemically Reactive substance on the Mendeleev Periodic Table.

Also, it can take forever to get every last bit of moisture out of the Evaporator Capillary Tubes when deliberately exposed to so much saturated atmospheric air. Dry Nitrogen on the other hand makes for the perfect vehicle to sop up all that residual moisture and leave the system Bone Dry. What @NJTB might have experienced was the dissolution of a small chunk of Ice that suddenly sublimated into the Freon Stream after blocking the passage of Gas adjacent the Evaporator Coils. When it lets go...it can surge quite dramatically... only to repeat this annoying cycle when the water droplets re-condense and re-freeze again and again down the line.

By the way... believe it or not...THIS phenomena of causing Ice Chunks to Freeze Up down inside of the A/C Lines will happen MORE often if the Technician uses an Excessively High Vacuum Pumping Rate...say... 3.5 to 6 Cubic Feet Per Minute versus a smaller 2.5 CFPM Harbor Freight Unit. Once the Ice Freezes...it becomes impossible to Evacuate the Moisture if it cannot achieve a Phase Change back into Water Vapor. Way too much ...of a Good Thing...

 

[TJBaker57]

What exactly do you think happens to an AC system when a leak occurs, and the system completely depressurizes and lets in atmospheric air through the leak? On a hot humid day? For months on end?

Give me a break. A little bit of compressed air pumping your system up for a short period to find a leak, followed by a vacuum pump to empty out the system is not going to be the hiroshima that all your large typing predicts.

You can do what you like.

A vacuum pump will never remove moisture that has mixed with PAG oil. Simply will not do it.

Many compressor failures are attributed to age when the real reason is prior mistreatment from non professionals.

For me, as a licensed HVAC journeyman in the business since 1984 I will continue to offer "best practices" advice to those willing to learn.

 

[JerryIrons]

You can do what you like.

A vacuum pump will never remove moisture that has mixed with PAG oil. Simply will not do it.

Many compressor failures are attributed to age when the real reason is prior mistreatment from non professionals.

For me, as a licensed HVAC journeyman in the business since 1984 I will continue to offer "best practices" advice to those willing to learn.

You want to say it's bad for the system, then just say it's bad for the system without all the drama and trolling. Every time I have put a vacuum on an ac system it's always "steamed" for a bit, that's the water boiling out a the lower boiling point under vacuum. So there's always some water from ambient air etc to get out when you are done working on an AC system. Heck opening up a bottle of pag oil and pouring it into the unloaded compressor or other new part you are exposing it to moisture just like that.
So at some point common sense has to prevail here.

 

[NJTB]

@MRRSM
Good explination about the ice in the line, never would have thought of that.
Way back in the day, the shop I worked in had a Robinair A/C station. It had a clear graduated cylinder on it, guages and a vacuum pump, with a freon can. You would pump the system down, add the proper amount of freon to the cylinder, and add to the system. Easy peasy.
The TB, I thought, should have been this easy, but turned into a pain, and after making sure everything on the guages and freon cans were tight and working, I started to wonder if something was preventing me from filling it properly.
Thanks again to all that replied.