A/C Problem. Need help with refrigerant type

[svxistentialist]

Anyone clued up on aircon? Hope you can help.

My a/c is currently not supplying cool air. I suspect that the refrigerant is low due to interference with the pipe when the tranny was fixed in Dec.

Ran the diagnostic, seems to be OK there. So I suspect low refrigerant or air in the system.

My question is this. If I want to get it topped up, can it be topped up with the newer refrigerant type? I am presuming being 91 it contains R12, so can I retain what R12 is in there, and top up with the newer type??

When it was working, it supplied arctic cool air. With the current hot spell we have, I need it working again, pronto.

Any advice appreciated.

Joe

[Earthworm]

Seems that most people lose their A/C after having their tranny serviced/replaced. There's a company called Redtek that makes R12 replacement.

http://www.sfrcolorado.com/tcbrr2.htm

[huck369]

I'm not an AC guru, but have been told that if you mix the 2 (R12 & R134) the different oils will gel and stop up the system.

You should still be able to get the R12 installed by a lic. AC guy, or you can update the whole system to the R134 , They sell a kit for about $30.00 that contains all the parts needed and the oil and R134 refrigerant.
I did this to my 92, and it has been fine (other than the slow leak in one of the hoses ).
I did remove the compressor and drain out the old oil before getting a vacumne pulled on the stystem, then just added the supplied contents, and it's cooling fine.
Hope this helps,

[Mr. Pockets]

Joe, what are your actual symptoms? Does the air work intermittently, working less the warmer it gets outside?

That was the case with the AC in my SVX. It especially didn't work on hot days in stop and go traffic.

What fixed my AC was washing out the radiator. Tons of dirt, leaves, rocks and bugs gummed up the bottom half of it, and washing it off returned it to its intended efficiency.

You can probably just stick a hose behind the radiator and spray it forward, but I think the best solution is to remove the whole thing to wash it, since the worst step there is draining the coolant.

[svxistentialist]

Thanks guys

The help is appreciated. Huck, who sells the kit, is it Subaru.com?

Nick, not so sure it is a clogged rad, but this is possible. I have had the tranny cooler installed between the rad and the condenser, and this probably would reduce the airflow getting through. I will check and attend to this.

As for actual symptoms, it heats up and defrosts quite OK. Getting cool air, no go. On a hot day, 18-20-20+ Celcius, put aircon on auto, nothing happens. Fan is not running, even if I demand cooling to 18, the lowest level available [you guys probably use degrees fahrenheit] When it was working, this would have the fan roaring till the cabin temp came down.

I figure the auto setting is telling the fan not to drive air into the cabin, as no cooling is available. By that I mean the control unit is not seeing the desired temperature differential, and is probably waiting for a cooler level, which does not happen, so it sends no air in. This is my own interpretation of what may be happening, but I know nowt about aircon.

I can manually switch on the fan to level 1, 2 or 3, and I get air, but it is warm or ambient air I get.

Is there a way I can check without gauges and stuff that refrigerant is low or not doing its job?

Thanks

Joe

[Earthworm]

That really sounds like low refrigerant to me. I've been in that position myself. One we started adding the refrigerant the A/C kicked in and started to cool. Before that the fan refused to automatically blow air into the cabin while on auto.

[lee]

Joe,

I'm not sure of the effect (gel mentioned earlier), but I do know no US technician would touch a car that has both kinds of refrigerant in the system. It contaminates their equipment. The is a definite process to the change - wish I could tell you more but I can't. I just know when I brought my 92 in for service they guy first checked for mixed gases and said he would do nothing if he detected them.

On to the low gas issue. If you still have R12, then with low pressure you should see a white bubbly/frothy mixture going by in the sight glass located on top of the receiver/drier - whenever the compressor is running of course.

[gl1674]

First, A/C system has a protection mechanism - if there is no pressure in the system, A/C compressor will not kick in and fans will not spin. This is done to protect A/C compressor - it is lubricated by the oil/refrigerant mix, nothing good would happen without lubrication. You can quickly check whether it is the low pressure or

Second, when I said pressure I meant the 70-80psi in a switched-off system any significant amount of freon would produce (at room temperature). Some of that freon would be in liquid form - the pressure in the system does not change whether it is 1/3 full or completely full - only amount of liquid freon would change. The practical use of this - if your compressor does not kick in because of the low pressure, you do not have practically any freon left.

Third, where did it go - leaked, automotive A/C systems are lossy by design. Either o-ring on pipe connection, or compressor shaft seal. If your engine compartment is reasonably clean, you can probably find the leak by just checking the connection points - refrigerant oil tends to thicken in the air and leave sticky dirty stains.

Fourth, the replacement refrigerant is a debatable area. Original system is designed for R12 and it performs best with R12.
Contrary to what some marketing departments want people to believe there is no drop-in replacement for R12

The only mainstream alternative is R134.
Before converting to R134 realize that:
a) It is less efficient than R12, your temperature will jump a few degrees up. I believe it is about 15% less efficient.
b) It has smaller molecules than R12 and it leaks faster. It will leak over time - partially through flexible hoses that do not have a coating that was added later to deal with R134...
c) R12 systems use mineral oil to lubricate compressor (it is simply mixed with R12 and circulates through the system). Oil is solvable in R12. Mineral Oil does not solve in R134 - you need to replace it with a R134-compatible lubricant. R134 lubricants are more agressive on o-rings - you definitely want to install new ones. Replacing lubricant requires removing compressor and draining oil and installing a new filter-drier.
If you do not replace lubricant, compressor seal will fail and freon leak out in a couple of weeks (speaking from first-hand experience here).

There are couple of different lubricant types for R134 systems, each with its own disadvantages, I don't remember details, but I believe ester is better than PAG for conversion from R12..

d) Either you go R12 or R134, you do not want any air in the system. If R12 molecules were leaking out, it means air molecules were leaking in. You do not want to just top-up, you want to evacuate air out of it and add refrigerant to a vacuum, not an air-filled system.
In the best case air would simply add the pressure on both sides of the A/C compressor - less efficiency, less cooling more horsepower loss. In the worst case the moisture from the air can freeze inside the evaporator and block the flow - possibly even destroying the compressor.

e) You can't check level of refrigerant in R134 by looking through the glass in filter-drier - this simply does not work.


My own solution was getting an A/C technician license ($20), vacuum pump ($70-compressed air driven) and R12 from Kragen ($40 for 2 cans, few years ago in 1999).

[gl1674]

The quick check whether you have low pressure or electrical problem is taking the connector from the evaporator and jumping the wires - if A/C clutch kicks in and fans start you do have low freon.

[svxistentialist]

Thanks guys,

This is all excellent information, and will get me to the root of my problem.

As it was working faultlessly last year, and the diagnostic ran its routines without an electrical error showing, I do suspect low refrigerant first and foremost. This will be compounded by the fact that the condenser out front will not pass air as easily with the extra [probably hot!] tranny cooler behind it.

Armed with the above information, I will go to a guy in North Dublin who does aircon. If he can refill R12, I will get him to do so and check for loose joints as suggested. If it has to be R134, I will get him to do a purge and refill with the new kit.

Thanks a million

Go raibh mile maith agaibh.

{That's the Irish for above, it means may you have a thousand blessings}

The Network comes up trumps again.

Joe

[Earthworm]

gl, what are your comments about the RedTek R12a product? I have been using that in my car for 2 years now.

[huck369]

Originally posted by svxistentialist
Thanks guys

The help is appreciated. Huck, who sells the kit, is it Subaru.com?

Joe

I got it at a local auto parts store "Advanced Auto" ,but have even seen them at discount stores like "Wal-Mart"

[Landshark]

Originally posted by svxistentialist
I have had the tranny cooler installed between the rad and the condenser, and this probably would reduce the airflow getting through. I will check and attend to this.Joe

i installed my cooler in between there and noticed no noticeable drop in cooling. even though R-134a is supposed to be 'not as good' at cooling as R12, my SVX has, without a doubt, the coldest AC of ANY car i've EVER been in! i love it! (especially after having two previous cars with less than adequate AC)

[gl1674]

from redtek.ca:

RED TEK® 12a, a HC-based refrigerant from Thermofluid Technologies, is a blend of environmentally safe hydrocarbon fluids designed as a direct replacement and retrofit refrigerant option for replacing R134a and R12 refrigerants in automotive air conditioning and refrigeration systems

My problems with it are:
1. It is not in wide-spread use, you will be hard-pressed to find an a/c service station that will knowlingly service your car. Most stations have only equipment for R12 and R134. They don't want to contaminate their equipment with anything else (and it is
illegal with huge fines). If you need to open your a/c system, your only choice maybe to wait until it leaks out completely.
It is very likely that it still falls at the same EPA rule as R12 which bans venting it to atmosphere ($10k fine for first offense) and requires recycling. Like R134 - yes you can buy it freely, no you cannot vent it into atmosphere.

2. It is a blend - it is not a single gas like R12 (F2Cl2CH4) or R134, it is a mix of different gases. In a lossy system (and all A/C systems are lossy) the different gases escape with different speeds - smaller molecules faster than the bigger ones. Over time the blend ratio in your system changes - this is uncontrollable, unmeasureable, there is no easy test (without a big chemical lab) to determine what is left. The only solution is probably a periodic recharge with fresh stuff - see item 1.

3. Redtek is "zeotrope" - from http://www.macsw.org/news/pr43096.html
"Some blend refrigerants are zeotropes, which exhibit some amount of temperature glide when evaporating or condensing. Others may perform like azeotropes (glide is not noticeable in normal operation, less than 3 F). In the case of zeotropes with glides greater than 3 F, one end of the evaporator will be warmer than the other. This may affect system performance. R12 and R134a are pure component refrigerants and do not exhibit this glide effect. (Source: Elf Atochem product information.)
Since automotive A/C system evaporator designs have multiple refrigerant flow paths, hot spots may occur in some systems when blend refrigerants are used. This will cause system outlet air temperature to be warmer. During A/C system operation, such hot spots may also cause an odor problem under certain heat load and driving conditions. "

Here is an interesting link to a discussion about DURACOOL refrigerants (essentially the same stuff, hydrocarbon blend)
http://www.ackits.com/forum/messagev...&threadid=6133

[gl1674]

Link to EPA web site.
http://www.epa.gov/spdpublc/snap/ref.../macssubs.html
This is probably the
Interesting notes:

1. There is no DIY exceptions for retrofit - you must place a proper lable and change fittings or you risk the EPA fine.

2. EPA has opinion that there is not a single "drop-in" replacement and the industry term usage is misleading.

3. R12A is banned based on potential flammability and insufficient data to demonstrate its safety.

4. Redtek is not EPA approved and therefore illegal for automotive use in USA. It is probably legal for your home
fridge or house aircon (but house aircon is likely to use something else anyway). Once again there are no DIY exceptions...