Anyone service their own a/c?

[adam2562]

curious if anyone has any knowledge on our a/c system. like how much refrigerant or what range it needs to be at to work effectively. i "think" had put too much so the compressor kicked on and off way too much and i read it usually does that when you have overfilled it with refrigerant. so i evacuated some and some and before i knew it i seem to have let out too much. just curious if anyone knows the correct amount it needs to be at

 

[rigtec]

curious if anyone has any knowledge on our a/c system. like how much freon or what range it needs to be at to work effectively. i had put too much so the compressor kicked on and off way too much and i read it usually does that when you have overfilled it with freon. so i evacuated some and some and before i knew it i had let out too much. just curious if anyone knows the correct amount it needs to be at

Hi adam,

Just so happens that I'm a tech in the commercial HVAC industry... With automobiles the refrigerant is usually weighed in using the o.z. scale because it takes such a small amount as compared to commercial systems e.g. 250 lbs and up! But that's okay, you can always start over. But I'd like to know what was the indication to you that it was low on gas, high discharge temperature, vehicle never seems to cool down... An automobile a/c system compressor is governed by a pressure or temp sensor; this sensor maintains the temperature of the evaporator; an aluminum coil where the refrigerant absorbs the heat from the cabin and then rejects that heat at the condenser in front of the radiator. This process cycles over and over to keep the cabin cool and dry.

The fact is that when the compressor starts cycling, it's doing that to prevent the evaporator from freezing-up. Usually when the compressor is 'Short cycling' it's telling you that the pressure in the evap is too low; which translates to dangerously cold temperatures. So a pressure switch will shut the compressor off to allow the evap temp to rise above the freezing point. Once the pressure rises enough (50-60 psi), the pressure switch will (make) bring the compressor back on in order to attempt to cool the cabin. Since you don't know just how much refrigerant is now in the system (assuming you don't have a set of gauges), it can be done this way... With the engine turned off, release the majority of the refrigerant.

Now the system will be "Under charged", way safer than an overcharge! Turn the system on with the truck running... the compressor shouldn't come on. That's because the system will prevent the compressor from running without any gas in the system... the idea is, if there's no gas in the system, then there's no oil capable of circulating through the system because the refrigerant carries the oil through the system and then back to the comp. With the windows opened, turn the blower on the highest speed and the temp control set to LOW. Begin charging the system slowly (if the manufacturer advises to invert the can then do so) but charge it slowly; don't want to over charge it this time. At some point the compressor will start to cycle quickly; this means that the system is working as it should.

The short cycling is a result of the extremely low pressures (unlike you were advised). As the pressure begins to rise you should feel the air temporature that's discharging from the registers beginning to drop. Now you need to place a thermometer in the center supply diffusers and while you're charging the system, you're watching the thermometer's reading drop in the 40 deg F range; depending upon the ambient temperature and cabin temps. If you can achieve a discharge in the range of 40 deg F with the blower on high speed then mission accomplished! That method imposes a worst case scenario on the system: having the windows down and the fan running on high speed.

Once you've raised the set-point and closed the windows the compressor will start cycling again because as the cabin cools down, so does the evaporator and so the low pressure switch is just protecting the compressor from dangerous conditions and, trying to maintain a comfortable environment for the driver/passengers, capish... Good! Let us know how you made out,

Cheers

 

[adam2562]

wow.. thanks for all your input! why aren't forums like that more often

unfortunately, i wasn't looking at the compressor cycles before i started adding. the reason why i felt the need to add some was because it just didn't seem as cold as a few years ago.. the truck is 5 yrs old i guess i felt it could be a little colder. i think i had added almost a full can which i later realized was too much and the compressor was on for 5 secs then off for 5-15secs. so i thought that was from over charging. so i let a bunch out and noticed the compressor staying on longer and from what i had read unless i misinterpreted it. that meant it was fine, but then i noticed the a/c was warm (when i had pumped a lot in there it was VERY cold).

addition::: now that it blows semi cold air.. the compressor is on more than it ever was once i started taking note.. just adding more info as i recall it

 

[tigger]

wow.. thanks for all your input! why aren't forums like that more often

unfortunately, i wasn't looking at the compressor cycles before i started adding. the reason why i felt the need to add some was because it just didn't seem as cold as a few years ago.. the truck is 5 yrs old i guess i felt it could be a little colder. i think i had added almost a full can which i later realized was too much and the compressor was on for 5 secs then off for 5-15secs. so i thought that was from over charging. so i let a bunch out and noticed the compressor staying on longer and from what i had read unless i misinterpreted it. that meant it was fine, but then i noticed the a/c was warm (when i had pumped a lot in there it was VERY cold).

addition::: now that it blows semi cold air.. the compressor is on more than it ever was once i started taking note.. just adding more info as i recall it

I did the same thing in my Honda and ended up destroying the compressor. Ended up having to replace the entire system due to contamination. I will always let a pro do it from now on. The $100 savings cost me almost $1000.

 

[rigtec]

"...i think i had added almost a full can which i later realized was too much and the compressor was on for 5 secs then off for 5-15secs. so i thought that was from over charging..."

At the point where it started "short cycling", you were starting to approach the proper level of refrigerant! Had you kept adding the refrigerant, you would have seen the short cycling begin to normalize e.g., stay on longer.

"...so i let a bunch out and noticed the compressor staying on longer ..."

Yes, it was staying on longer because the evaporator was not cooling down as rapidly, but rather, warming up and so had no reason to cycle as often!

"...addition::: now that it blows semi cold air.. the compressor is on more than it ever was..."

Toyota's a/c systems are extremely efficient and can produce a forty degree differential (Delta-T) which means: the cabin can be 80 Deg F but it can still produce a 38-40 Deg F discharge air temperature! Most residential and commercial bldgs are only expected to produce a 10 to 15 degree (Delta-T) differential e.g. 75 deg F in-room (return air) temp and a 60 degree F discharge air temp; about 15 deg F differential is design or textbook!

Oh... Don't forget to check your cabin air filter. If it gets clogged, the discharge air will be restricted at best and the evaporator will accumulate water droplets and freeze up causing the compressor to lock out due to the low pressure condition that this creates; hence... a NO-COOLING or POOR-COOLING scenario! Also, the a/c condenser should be power washed with detergent on occasion or a high refrigerant pressure condition may prevail, robing the system of it's high efficiency and hindering it's heat rejecting properties essential for removing massive heat loads from the vehicle's cabin and reducing the evaporator's ability to cool the vehicle as it should!

These are just a few things that are often overlooked (even by professionals) when evaluating the performance of your vehicle's a/c system. The cabin filter cleaning and condenser's detergent pressure washing should 'Always' be done BEFORE a refrigerant level adjustment is made because the condition of these components directly affect the pressures operating in the system. So an over charge or under charge of refrigerant can be expected if the basic system maintenance is neglected before the refrigerant charge is adjusted. Hope this helps,



Best to you! rig

 

[adam2562]

[MENTION=83083]rigtec[/MENTION] i appreciate your help!. i'm on Vacay and my gauge that came with the bottle is at home, i'm still getting enough cool air to get by. i'll address it after the holiday. Thanks!

 

[Antman]

At the point where it started "short cycling", you were starting to approach the proper level of refrigerant! Had you kept adding the refrigerant, you would have seen the short cycling begin to normalize e.g., stay on longer.



Yes, it was staying on longer because the evaporator was not cooling down as rapidly, but rather, warming up and so had no reason to cycle as often!



Toyota's a/c systems are extremely efficient and can produce a forty degree differential (Delta-T) which means: the cabin can be 80 Deg F but it can still produce a 38-40 Deg F discharge air temperature! Most residential and commercial bldgs are only expected to produce a 10 to 15 degree (Delta-T) differential e.g. 75 deg F in-room (return air) temp and a 60 degree F discharge air temp; about 15 deg F differential is design or textbook!

Oh... Don't forget to check your cabin air filter. If it gets clogged, the discharge air will be restricted at best and the evaporator will accumulate water droplets and freeze up causing the compressor to lock out due to the low pressure condition that this creates; hence... a NO-COOLING or POOR-COOLING scenario! Also, the a/c condenser should be power washed with detergent on occasion or a high refrigerant pressure condition may prevail, robing the system of it's high efficiency and hindering it's heat rejecting properties essential for removing massive heat loads from the vehicle's cabin and reducing the evaporator's ability to cool the vehicle as it should!

These are just a few things that are often overlooked (even by professionals) when evaluating the performance of your vehicle's a/c system. The cabin filter cleaning and condenser's detergent pressure washing should 'Always' be done BEFORE a refrigerant level adjustment is made because the condition of these components directly affect the pressures operating in the system. So an over charge or under charge of refrigerant can be expected if the basic system maintenance is neglected before the refrigerant charge is adjusted. Hope this helps,



Best to you! rig

^^^ That's some good stuff right there!

I accidentally unbolted an A/C pressure line union during my dual battery install and got a face full of Freon in the process (didn't feel good for a week after). I don't mess with that stuff but Scott@Hightech hooked me up and fixed it up right away. Been running great ever since!

 

[flighht2k5]

curious if anyone has any knowledge on our a/c system. like how much freon or what range it needs to be at to work effectively. i had put too much so the compressor kicked on and off way too much and i read it usually does that when you have overfilled it with freon. so i evacuated some and some and before i knew it i had let out too much. just curious if anyone knows the correct amount it needs to be at

You realize it's a 25000 dollar fine to willingly evacuate refrigerant right?

 

[rigtec]

You realize it's a 25000 dollar fine to willingly evacuate refrigerant right?

...that's only if you get caught in the act lol!

 

[adam2562]

You realize it's a 25000 dollar fine to willingly evacuate refrigerant right?

i used a friends evac pump

 

[rigtec]

"...I accidentally unbolted an A/C pressure line union during my dual battery install and got a face full of Freon in the process (didn't feel good for a week after)..."

Hahaha! ...remind me to tell you about the time that I blew myself up in a mechanical room.... I was replacing the valves on a rather large tonnage (200 ton) chiller; the compressor looks just like a small block (327) Chevy engine. This was a new company that I was working for so I was a little nervous that day!

I had removed all of the head-bolts and was about to tap on the heads to break them loose from the baked-on head gaskets, when all of a sudden ...Kaboom! Seems that I had left out one important step of this job... I had forgotten to turn the machine off first and so it started running hahaha! As a result there was an intense flash and a really loud explosion because the cylinder head went "airborne" and landed inside of the "3 Phase, 480 volt electrical panel!

Nothing got damaged except for my ego... When the facility mgr came running in to the room to investigate the loud explosion and black plume of smoke he said: "what was that noise"? I just said... "what noise?" Then I got up off the floor and continued working! He just gave me the strangest look and walked out! "Totally humiliated!" out: Needless to say; I never forget to turn stuff off before I begin working on it! LOL!

 

[Saker]

Hahaha! ...remind me to tell you about the time that I blew myself up in a mechanical room.... I was replacing the valves on a rather large tonnage (200 ton) chiller; the compressor looks just like a small block (327) Chevy engine. This was a new company that I was working for so I was a little nervous that day!

I had removed all of the head-bolts and was about to tap on the heads to break them loose from the baked-on head gaskets, when all of a sudden ...Kaboom! Seems that I had left out one important step of this job... I had forgotten to turn the machine off first and so it started running hahaha! As a result there was an intense flash and a really loud explosion because the cylinder head went "airborne" and landed inside of the "3 Phase, 480 volt electrical panel!

Nothing got damaged except for my ego... When the facility mgr came running in to the room to investigate the loud explosion and black plume of smoke he said: "what was that noise"? I just said... "what noise?" Then I got up off the floor and continued working! He just gave me the strangest look and walked out! "Totally humiliated!" out: Needless to say; I never forget to turn stuff off before I begin working on it! LOL!

I can't believe they didn't have it locked out and tagged out prior to you working on it!
You were being watched over that day!

 

[catrains]

curious if anyone has any knowledge on our a/c system. like how much freon or what range it needs to be at to work effectively. i had put too much so the compressor kicked on and off way too much and i read it usually does that when you have overfilled it with freon. so i evacuated some and some and before i knew it i had let out too much. just curious if anyone knows the correct amount it needs to be at

auto vehicles use R134 refrigerant. R12/R22 is a freon refrigerant which is not to be released into the environment. these freon types are ozone damaging which is why the EPA has fines if caught discharging.

R134 is environmentally friendly refrigerant. so leakage does not damage anything also safe on you . having worked with those r12/r22 they are very bad to breath in and if smoking in the gases it will possibly kill you so this is why we have R134 today 1996 Is when they made the switch over.

when charging any vehicle you must have the pressure temperature OEM chart. with a R134 gauge set you monitor the pressures high and low side test ports. you also take the air temp .

as an example on a vehicle I have charged in the past @80 deg F the low side 40-45PSI the high side 225PSI . this is saying the ac system is properly charged and operating normally .

there should be a chart available that specifically gives the details on the charging of refrigerant. dumping out all the refrigerant then adding to correct weight amount may still mess things up..

the ac condenser and evap/air filters must be cleaned . fans on max. doors all open , then start the charging / testing procedure based on your OEM manual spec sheet for the pressure / temp correlation .

there are many that overcharge the system . they only use the low side pressure and that is the problem too much pressure will damage the hoses and compressor. also do not add any conditioners/sealers / oil etc unless it is approved by the manufacturer..

if you operate in 120 deg f temps it is very important never to add too much better be slightly low as the pressures can get up to 400PSI.

 

[renau001]

Hahaha! ...remind me to tell you about the time that I blew myself up in a mechanical room.... I was replacing the valves on a rather large tonnage (200 ton) chiller; the compressor looks just like a small block (327) Chevy engine. This was a new company that I was working for so I was a little nervous that day!

I had removed all of the head-bolts and was about to tap on the heads to break them loose from the baked-on head gaskets, when all of a sudden ...Kaboom! Seems that I had left out one important step of this job... I had forgotten to turn the machine off first and so it started running hahaha! As a result there was an intense flash and a really loud explosion because the cylinder head went "airborne" and landed inside of the "3 Phase, 480 volt electrical panel!

Nothing got damaged except for my ego... When the facility mgr came running in to the room to investigate the loud explosion and black plume of smoke he said: "what was that noise"? I just said... "what noise?" Then I got up off the floor and continued working! He just gave me the strangest look and walked out! "Totally humiliated!" out: Needless to say; I never forget to turn stuff off before I begin working on it! LOL!

Wow, being in the OPS dept at my plant and being responsible for tagging out equipment to work on, I can't even imagine that. I guess this was before the days of OSHA and a lockout/tagout program?

 

[rigtec]

I can't believe they didn't have it locked out and tagged out prior to you working on it!
You were being watched over that day!

I know that's right bro!

Umm, actually the 'Lock-out, Tag-out' procedure is the technician's responsibility! In my own defense though, I did remember to turn off the 115V panel switch, but that (obviously) doesn't kill the entire control panel. It only disabled the remote temperature controller in the utility closet and initiates the daytime & night set-back temps and schedule. But the high voltage supply panel is left on which manages the system refrigerant "Pump-down" controller and crankcase heater circuitry, blah, blah, blah!

Even though I had never been in that bldg before that day I understand how these systems work. None of the thermostats in the bldg control the chillers, or boilers. They 'modulate/demodulate' the VAV (variable air volume) dampers in the ceilings; which provide cool air to the occupied space. The chiller isn't controlled by the t-stats. It's controlled by an aqua-stat which monitors the cold water temperature in the chiller barrel; and maintains the chilled liquid temp at 44 degrees F at all times. Anyway, this being 18 or 19 years ago was still my own fault for letting the "Opening night jitters" affect my concentration that way! ...and it's never happened again!

I know that this experience was way O/T, but I was sharing this hvac disaster with [MENTION=65614]Antman[/MENTION] because he shared a similar hvac Boo-Boo with us so my point was that when we're working with chemicals of this magnitude and being distracted, we can all mess up! Just so glad that he didn't get seriously injured; any refrigerant coming in contact with the eyes can cause Permanent eye damage... glad it turned out okay Jeff!

Best!

 

[rigtec]

Wow, being in the OPS dept at my plant and being responsible for tagging out equipment to work on, I can't even imagine that. I guess this was before the days of OSHA and a lockout/tagout program?

"JUST TO BE CLEAR"

The building that I was working in that day wasn't plant work, it was a commercial office building with a large warehouse on site with it's own mechnical room. There's no safety crew or three day accident awareness courses to go through before being allowed to work at that sight. As a tech in the HVAC technical industry, you will most likely be dispatched to a different facility everyday so you need to find the system(s) at fault right away!.

Also, you are usually troubleshooting various brand names of equipment, some manufacturers are still around but some companies have long passed on e.g. Westinghouse, Typhoon, Singer, Nesbitt, Melco, Jackson-Church... to say nothing of the industry standards: Carrier, Trane, York, McQuay, Monmouth, Liebert, Bohn...etc! And we the technicians must be familiar with each one of these names to cut-down on service time (invoicing). And I must say that over a period across thirty years you can become familiar with the equipment, but there's never a dull moment!

The regretful error that I've described in an early post really had nothing to do with OSHEA being available or a 'Lock-out' Tag-out program or whether I was familiar with safety rules or even the equipment in the building. I don't know just how long you've been working in a safety awareness capacity, but I believe my point was particularly clear which was NOT to allow yourself to become distracted or sidetracked because safety comes first. And at the beginning of that post I said that it was my own fault for allowing myself to become preoccupied with the fact that it was a 'First day on the job' scenario, but I also said that it has never happened before that, and has certainly never happened again across a thirty year period of working in the same field!

Cheers

 

[BobsTrail]

Not off-road related, but one of the more interesting series of posts in a while. My son has his Commercial A/C certification and he found it very interesting.

 

[rigtec]

auto vehicles use R134 refrigerant. R12/R22 is a freon refrigerant which is not to be released into the environment. these freon types are ozone damaging which is why the EPA has fines if caught discharging.

R134 is environmentally friendly refrigerant. so leakage does not damage anything also safe on you . having worked with those r12/r22 they are very bad to breath in and if smoking in the gases it will possibly kill you so this is why we have R134 today 1996 Is when they made the switch over.

when charging any vehicle you must have the pressure temperature OEM chart. with a R134 gauge set you monitor the pressures high and low side test ports. you also take the air temp.

as an example on a vehicle I have charged in the past @80 deg F the low side 40-45PSI the high side 225PSI . this is saying the ac system is properly charged and operating normally.

there should be a chart available that specifically gives the details on the charging of refrigerant. dumping out all the refrigerant then adding to correct weight amount may still mess things up..

the ac condenser and evap/air filters must be cleaned . fans on max. doors all open , then start the charging / testing procedure based on your OEM manual spec sheet for the pressure / temp correlation.

there are many that overcharge the system . they only use the low side pressure and that is the problem too much pressure will damage the hoses and compressor. also do not add any conditioners/sealers / oil etc unless it is approved by the manufacturer..

if you operate in 120 deg f temps it is very important never to add too much better be slightly low as the pressures can get up to 400PSI.

Hi catrains,

Your post is very interesting to say the least! My first question to you is: "How many years have you worked in the Air conditioning/Heating field?" Hoping you can give a little detail just for clarity!

What was it that inspired you to approach [MENTION=45721]adam2562[/MENTION] question(s) in this manor; He had specific things that he wanted to know which he very articulately layed out, but you didn't answer any of his questions. Instead, you decide to teach us the "proper way to test and to charge a car air conditioning system"... Clearly your method will not help him... you even decided to lecture on "The clean air act of 1996" posted many times on the internet by the EPA and other government agencies"!

What type of EPA Certifications do you hold right now: type 1, type 2 or type 3 (Universal)?

You see catrains, Adam is just beginning to learn about the HVAC system in his vehicle, he revealed that when he was unsure of what a cycling compressor is doing; he thought it meant that it was overcharged... that's how I knew how to help him and explain how he can get the system back up and running without P/T charts and a full manifold set with a high and lowside gauge... Did you know that he can Legally release a nominal amount of refrigerant into the atmosphere without consequence? Hmmmm?

The US government has made a provision for the release of a de minimus amount of freon e.g., R-12, R-22, 134A. When a technician is attempting to locate a refrigerant leak in a system, a Trace charge of freon is first added to an empty leaking system. Once the refrigerant trace charge is added to the system a high pressure charge of Dry Nitrogen is added. An electronic leak detector is then used to interrogate the entire system until a trace sample of the pressurized refrigerant is located. Once a leak is located, you are allowed by law to release it into the atmosphere. If it is later noted that there may be additional leaks in the systems piping or other components, then the process is performed again, or as many times as it takes to locate the LEAKS (as in more than one leak in a system)! So to release five pounds (LBS) of freon in an effort to eradicate a problem would not be considered excessive!

BTW: I wish you wouldn't have posted the above statements because they don't match the OP's questions, and that's because they're 'Copy/Paste' from the internet... every last paragraph! When I added your above post... I had to reformat the sentences and punctuation because they were selected from another text online and so didn't fit the page format here. Just to be clear: nothing wrong with using copy/paste to transfer documents to this forum; I've done it in some of my tutorials, BUT, I'll ALWAYS explain where the text came from and usually leave a link so the community can find it and use it in their own studies and technical files!

rigtec

 

[renau001]

"JUST TO BE CLEAR"

The building that I was working in that day wasn't plant work, it was a commercial office building with a large warehouse on site with it's own mechnical room. There's no safety crew or three day accident awareness courses to go through before being allowed to work at that sight. As a tech in the HVAC technical industry, you will most likely be dispatched to a different facility everyday so you need to find the system(s) at fault right away!.

Also, you are usually troubleshooting various brand names of equipment, some manufacturers are still around but some companies have long passed on e.g. Westinghouse, Typhoon, Singer, Nesbitt, Melco, Jackson-Church... to say nothing of the industry standards: Carrier, Trane, York, McQuay, Monmouth, Liebert, Bohn...etc! And we the technicians must be familiar with each one of these names to cut-down on service time (invoicing). And I must say that over a period across thirty years you can become familiar with the equipment, but there's never a dull moment!

The regretful error that I've described in an early post really had nothing to do with OSHEA being available or a 'Lock-out' Tag-out program or whether I was familiar with safety rules or even the equipment in the building. I don't know just how long you've been working in a safety awareness capacity, but I believe my point was particularly clear which was NOT to allow yourself to become distracted or sidetracked because safety comes first. And at the beginning of that post I said that it was my own fault for allowing myself to become preoccupied with the fact that it was a 'First day on the job' scenario, but I also said that it has never happened before that, and has certainly never happened again across a thirty year period of working in the same field!

Cheers

Sorry, I hope what I said did not come across as a slight or dig, but I'm afraid it did. I don't work in a safety awareness capacity, I prepare and execute tagouts for folks to work behind including our four 100+ ton chillers on a few occasions. I only meant to point out how different the environment is now where I work compared to what you described. Agree 100% that the worker must have primary responsibility for his safety, which is something I'm afraid gets lost where I work since a different department executes the tagouts than does the actual work.

Thanks for sharing your experience and the help you provide to the forum.

 

[rigtec]

Sorry, I hope what I said did not come across as a slight or dig, but I'm afraid it did. I don't work in a safety awareness capacity, I prepare and execute tagouts for folks to work behind including our four 100+ ton chillers on a few occasions. I only meant to point out how different the environment is now where I work compared to what you described. Agree 100% that the worker must have primary responsibility for his safety, which is something I'm afraid gets lost where I work since a different department executes the tagouts than does the actual work.

Thanks for sharing your experience and the help you provide to the forum.

Hi renau001,

No offense taken! My point to you was just that it's different working with In-house staff and working as an outside contractor's field technical team. The safety procedure is the same, but at that time, my first day on the job and I get handed a s#it job that somebody else (who no longer works for the company) started a good while ago. Some of the parts are there and I can see that some of the gasket kits are opened up, I see a part of the new valve plates missing and an oil pump on the floor...

So I'm gettin' frazzil-dazzled because I've got to make this compressor run right and it looks to me like half of the parts that were ordered are in very bad condition. So I'm under the gun because if this compressor takes a $%it when I start it, I'll have to take the bullet for it... don't forget that this is my very first day with the company and my first time seeing this dysfunctional chiller! Long story short, the chiller was up and running by 4:00 PM that afternoon and in spite of everything that went wrong on that job, I still "looked" like a hero!

I guess what I took away from this horrible experience is: "Never allow fear to alter your approach!" :usa2:

rig