Former User

This statement is contrary to the common and acceptable practice of using a manifold gauge set to diagnose A/C problems. This is also the key diagnosis tool discussed and recommended in this thread.

I am sure that bad refrigerant and oil products can be found on the market. I also agree that sealants should never be introduced into any A/C system. Nonetheless, despite your doomsday outlook, informed DIYers are able to purchase bona fide R134a (1,1,1,2-Tetrafluoroethane) and the appropriate oil from local and online retailers.

If you had read my question carefully, you would have recognized that I was asking about vacuuming air from the manifold gauge set, not the A/C system.

You seem insistent on jumping to conclusions. I have no interest in taking any shortcuts that create problems. As H-T members are highly interested in DIY projects, my questions simply seek to root out what a DIYer who does not have access to a RRR machine should and should not do with respect to A/C work. slowcivic2k recommends a DIYer not top off an old A/C system that's a bit low on refrigerant. I was simply trying to figure out whether there are acceptable workarounds for the issues he mentioned -- nothing more, nothing less.

Please correct me if I am wrong, but the only item that I see that must be done with a RRR machine is recovery of existing refrigerant in a system. It seems to me that a DIYer can replace the receiver/dryer, vacuum the system and check for leaks, and then recharge the system with the correct weight of refrigerant and volume of oil using a manifold gauge set.

theghost25

I have a 2003 Accord with dual zone climate control.
I am replacing the compressor, condenser, dryer/receiver, and expansion valve.

Can anyone help me with a diagram or instructions on changing the expansion valve??
I have a Snap on Kool care cart to use for the recovery/charge of the system and the compressor, condenser and dryer should be staright forward.


Any help greatly appreciated

fcm

We charge $20 for a nitrogen pressure test $120 for a evac and recharge, [1hr on vacuum pump] $2.00 oz for R134a refrigerant and another $20 for shop supplies, [any O rings, oil and so on] add another $15 if you want UV dye added for future leak detection, that's almost 50% what the Acura dealer charges, but about the going rate for A/C shops in my area.
http://www.airwolfeautoair.com/ 94

Former User

Thanks fcm. Do you also offer refrigerant recovery alone and, if so, what would your shop charge for it?

In addition, where do you fall on the topic of DIYer A/C work done without an RRR machine? Aside from refrigerant recovery, can it be done correctly if proper care is taken?

slowcivic2k

The filtering element need only be replaced if the system is opened for a major repair, (IE a line, compressor, etc) or if it has had a track record of being recharged due to a leak that was not fixed. Service fittings and some pressure switches do not require evacuation to remove, as removing the switch will close a valve as it is removed, generally seen on domestic vehicles.

An evacuate and recharge varies in price, but generally for a Honda, would run about 140-180 dollars including refrigerant. I usually sell parts on that type of service, at least new service ports and caps, and the addition of 1/4 to 3/4oz of refrigerant oil with a tracer in it to find possible leaks. So if your system is severely low, but doesn't leak readily, expect to pay around 200 dollars at the absolute most, anything more is a rip to say the least.

Now, if your A/C does not function, that is usually a separate diagnostic process, and will cost more in addition to the evac and recharge.

Replacing the filter shouldn't cost a whole lot, as Honda uses a similar filter design on most of their models, after that you are at the mercy of that shops labor rate and the location. $150-200 doesn't sound out of range, for a shop that is....


Choosing a shop is not as important as choosing the tech who works on your car. Obviously you want to make sure the shop has relatively new equipment to service your car. I wouldn't want someone doing A/C work on my car with 10 year old equipment, but it is all for none if your tech is an idiot. KNOW YOUR TECH! It is to your advantage.

Just today I had to save a comeback A/C job from becoming a near disaster because the tech that worked on it before I did didn't bother to note the radiator fan wasn't operating, and the high side pressure took off to nearly 450psi, nearly reaching the failsafe rupture pressure. Tell your A/C compressor to work at 450psi for a few hours, and it will hate you very shortly. Customer complained of a constant stall/idle drop after driving around... lol some people I tell ya..

fcm

We charge $50 for recovery, waved if we do the recharge.

Unless you have a gauge set and vacuum pump and recharge cylinder or RR unit or access to them I do not recommend DIY.

One thing I have not seen mentioned is the use of an "identifier" a unit used to identify exactly what and how much, [% wise] what is in the A/C system, very important.

If I identify a system and it comes up 100% R134A, [no air, R12 R22, and absolutely no hydrocarbons] and customer wants, I will boot up a system, [add refrigerant].

I do not recommend a DIYer boot a system, especially with over the counter cans of DIY A/C "fix", even if it is 100% R134a.

Sorry got to go to work and boot up a Limo. 94

Former User

Can you explain why a recharge cylinder would be different from a can of pure R134a and why you don't recommend the latter?

Does the identifier simply do a chemical analysis of the gas inside the system. Is such a device available to the regular consumer?

DCFIVER

3 professional techs in this field have already explained to you various reasons why you shouldnt try to service your AC system. I see you will not be deterred. I applaud your ability to perform your own repairs. But as I stated earlier this was not meant to be a DIY service. You will cause more harm then good in the end. Good luck...(BTW any of the equipment we use is available to the public. Problem is price. It would be much cheaper to pay a couple of hundred bucks to have the system serviced than to spend a few thousand on equipment you may use once or twice. *Yes an identifier uses simple gas analysis)

slowcivic2k

A good refrigerant identifier will be able to determine R12, R134a, R22, HC, and with a filtering assembly, for the presence of sealer in the system.

I don't mess around with sealers, if it tests positive for sealing agents, the whole system get flushed, compressor comes out, expansion valve gets replaced, and everything gets re-oiled followed with a 2 hour vacuum.

Mix refrigerants together and it goes to the trash pump/container.

EPA 609 certification only certifies that the individual is "trained" or as it be "advised" on the proper procedure for servicing A/C systems that are mobile. It does not cover diagnostics, that is left to the aftermarket.

I have used manifold gauges in the past, I have two sets of 134a manifolds, and a single RRR machine. I used to use them all the time, problem was you can drop them, enough said LOL. Nothing like 400+psi going up the hose, and pulling the manifold off the hood striker.

Like I've said before, I am a true believer in NO AIR whatsoever. Any time you connect to a system, you let some air in, any time you take them off, you let some refrigerant out. During any A/C performance check, the RRR goes on, do a quick pressure check, evac, and then re-dispense what it had in it, simply because I do not want even the smallest amount of air in there.

The only way a DIY can do A/C work correctly, is to have the refrigerant recovered. Then he can tinker around all he wants, even vacuum it out if the pump is strong enough to verify the repairs. Then have the shop recharge it. You could at that point refill it yourself, but every time you hook up, air goes in, even just a little.

Former User

Thanks for taking the time to explain everything so clearly.

dallison

good info, this along with a timing belt are two things i will never do on a car. There are too many things that can go wrong quick and you need too much equipment to perform it.

fcm

As has been explained, with a "can" of R134a and DIY, you have no way of knowing exactly how much refrigerant you are putting into the system, even if the system has been recovered and you have evacuated it properly, you can not be sure the can has the stated amount of refrigerant in it.

Also as mentioned, yes, an identifier analyzes what is in the system, this is one of the ones we use... http://pdf.directindustry.com/pdf/ne...868-79006.html over $1000

This is the one we have in our truck for mobile work, [body shops and so on]... http://www.canadiantechnician.com/pr...?intDocID=2855 over $500

A manifold gauge set will cost $200+
A vacuum pump, [even a small 2.5 CFM one] will be $100+

That's over $300, and that's more then it would cost for a shop to do a proper recharge.

So if for no other reason DIY A/C recharging is not cost effective. 94

Former User

I have accurate weight scales, so why wouldn't weighing valve-tapped R134a cans before and after adding refrigerant to the system alleviate this^ concern? For example, the capacity of my Civic A/C systems is 21-23 oz, so I would buy 2-12 oz cans of R134. I would then empty the first can into the system and then all but 1-2 oz of the second can. Again, the total weight of refrigerant added to the system would be verified by the before and after weights of the cans.

I already have a MasterCool R134a manifold gauge set for which I paid $50. Seems to work fine. I also have three cars with A/C, so investment in a vacuum pump or rental of one might end up being the most economical option when the time comes.

By the way, I really appreciate all of the professional opinions, suggestions, and information given in this outstanding thread.

fcm

If you can weigh it accurately and charge it into the system properly, then it should not be a problem. 94

bigJOE671

Here is my problem, My AC only works when I'm driving

Before this problem I installed a whole ac system(compressor, condenser, drier, low and high side lines, and evaporator) since my car was jacked up from the beginning with all the ac components. I got the donor system from a junkyard. The car system still had freon so i knew the system was still in good shape. Not to mention this is my first time doing ac work. So when I installed and recharged the system the ac blew at 45 degrees F at the vent on Idle (1000rpm) ambient air temp 80F, humidity 50%, windows rolled up, and blower fan at max. Thing was that the connector on the drier wasn't sitting properly so I had fix that. The system worked liked this for about 5 days then I went ahead to fix the drier line.



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When I got the system evacuated from freon. I disconnected the drier line and a whole bunch of oil came out (I guess the system still had some freon)! So I poured some oil into the drier and continued to put the lines back together. After fixing the drier line and putting an extra o-ring at the line because it couldn't hold a vacuum . I vacuumed the system and held it at -29hg for 30 mins then turned it off to check for leaks for about half an hour. Leak checks good so I continued on with charging the system. This is my third time charging this system with about 18oz of R-134a. I used two cans 12oz each but purged the gauge lines of air.

So now when I checked to see if the air got cold it held at 55F at the vent on Idle (1000rpm) ambient air temp 85F, windows rolled up, and blower fan at max. It held good and pressure readings were at low side 40 psi high side 210psi.

Next day the car only started to only get cool when driving. It got cool after about 2 mins of cruising at 50-60mph, 3000rpm, and vent temp would be around 55-60F at 85 Ambient air temp. Then when at idle at a stop light the temp would go up like the ac ain't working at all. This is becuase my compressor would cycle off every 1-2 minutes at idle then turn on after 3 mins then it would repeat that whole process just at idle. I can't tell if the compressor cycles off/on when cruising at all.

Gauge readings after all this happened: Hooked up gauges engine not running saw static pressures low and high side equal at 75psi. Started car then low side reached 45psi and high side would climb to 370psi then shutoff ambient air temp 80F. This process would repeat itself at idle. The condensor fan would stay on whenever I turn on the ac and only shuts off when the ac is off.

At night, ambient air temp 70, and driving the vent temp would be 43F. It would still heat up though when sitting at Idle.

I'm thinking my TXV is fine becuase the temp still reaches 45 degrees at vent when driving, blockage somewhere, or I have too much of something in the system. I'm thinking about flushing the whole system, replace the txv and drier, then recharge. But i'm running out of funds.

Well what do you guys think is the problem?

slowcivic2k

Obviously you have a high pressure problem, air in the system, blockage in the condenser internally, poor airflow over the condenser, too much refrigerant, or blocked metering device. All except the last one manifest with poor cooling at idle.

You found the right place to fix your problem, all you have to do is read my posts and you'll get your answer. Next time please start your own thread, this is a diagnostic procedure and informational thread, I would like it to not get cluttered.

bigJOE671

I can't start my own thread if i'm a brand new member. Got to post some posts.

kidcool1977

Dumb question but I will ask.

What are the common places for leaks in the Ac system.

slowcivic2k

A/C systems can leak from a variety of places, it mostly depends upon the installation of the system in the vehicle. Some manufacturers keep all the A/C components close, while others throw them all over the place carelessly.

The service ports are leak spot number 1, and always will be. They generally do not leak until serviced, but after that it seems to be a downhill trend.

Since the compressor is the only moving part that has to seal as it functions, it tends to leak more than most other parts.

The A/C condenser on most vehicles is exposed to road debris to some extent, which can cause complete loss of refrigerant.

The rubber barrier hoses would be the next likely weak spot. They have to flex, absorb vibration, tolerate extreme heat, and allow enough refrigerant to flow without compromising performance. Refrigerant is abrasive to some degree, just like the Colorado river. Eventually the rubber will deteriorate, and can collapse or explode.

The evaporator can be a problem spot due to corrosion caused by debris building up on the coil. Besides the mildew, it creates a spot for the aluminum to be attacked directly, causing small pin holes over many years.

So to sum up, Service Ports, Compressor, Condenser, Hoses, Evaporator. Most of the other parts will not leak unless they are deliberately damaged or exposed to the elements. (Good example is the Filter/Accumulator on a 2002-2005ish Ford Focus, placed in the wheel well on the passenger side, once the fender liner is damaged, its game on.)

Civic1.6EX

Hey slowcivic...

That was a great writeup you did. I just wanted to clarify about the readings that you said about fluttering, jittering high side pressure. If they do this for about a 10-15psi range, does that still mean that you have a bad reed valve in the compressor?

Thank you for your time.

Muckman

iTrader: (2)

Here is a question for the professionals: How do you determine how much oil the system needs?

As far as I know there is no way to accurately gauge how much oil is in the system. The factory service manual outlines how much oil a new system from the factory should have and how much oil to add if a component is replaced. But what if the system was leaking or was over filled or under filled previously? Can you explain the correct methods to service the AC PAG oil?

DCFIVER

It varies between manufactures. For the most part, you pour in the same amount of oil that comes out of the old compressor. If no oil is in the old compressor, add the proper amount. Thats all that really matters as the remaining parts of the system retain whatever oil they contain until the system becomes dynamic again.
(also there are RRR machines that will draw out the oil into a graduated container.)

honshu

Bump for an awesome write-up.

bigJOE671

Just to let you know I found out the problem...It was a weak fan motor!
Changed that and the system works great!

DCFIVER

That would be one of the problems he indicated to you "poor airflow over the condenser"