Air Conditioning Tech Thread.

[Rhyno]

Hi Again,

SOO00oo.. you are obvisouly suffering a bit and want colder air-conditioning in your car.

My question is this Z2TT; how have you determined that the fan in your A/C system is the limiting factor?

Did you determine this from monitoring your suction and discharge line pressures on your AC system while the car was stationary?

Or is because your system works great when you are driving but struggles when stationary? If that is the case you will proberly find you have a combination of two problems:

1. Lack of air flow throught the condensor (due to damage and/or lack of servicing; very common or lack of cowling/shroud)

2. Engine not being reved so not circulating enough gas to remove the neccesary heat. (Ineffeicent Compressor)

These 2 problems (beside's having a leak) are the two most common problems on car airconditioning systems.

With the infomation I have at hand about your car, at this point of time I would recomend two things.

Firstly if you know a fridgey (refrigeration mechanic) hit him up to clean your condensor for you (chemical clean, not hard, could even do it yourself if your keen) OR go to your local serve-your-self car wash shop, and (lightly) coat your condensor with heavy duty degreaser, rinse and repeat at least 3 times, this should help a bit. You will be surprised at the amount of shit you can get out!

Then whack two small A/C fans on the front of the condensor, that are controled by a bi-metalic switch or a themostat hooked up to one of your A/C lines.

Or you could go seper duper dodgey brothers, and just loop a relay from your handbreak or break pedal or something that you press when in traffic, to bring on the fans when stationary or near stationary. Dodgey - but it WILL work.

Just my 20 cents...

P.S. If you want even better AC, you can insulate your Suction and Liquid lines in the same run of insulation, will save you $$$ on fuel too, over time.

[Rhyno]

"My Low side a/c line is wrapped in some sort of plastic tape, not sure if I should wrap it with something else or leave it be.

I'm wondering why do most factory setups have quite some spacing between the radiator and the condenser (see my diagram), that further decreases the draught as air will flow through the path of least resistance, and that is through the sides, so not as much will draw through the condenser especially with a viscous hub fan at idle"

To answer your first question, yes proberly. Any pics? At the end of the day it won't make a HUGE difference, but every bit counts, just like squeezing every pony out of a engine, it all adds up, but in a saving on fuel instead.

Secondly, as far as I understand the reason these gaps are there are to prevent worse case scenarios. Imagine, if you had a retard rallydriving his car through the bushe's blocking the condensor up with weeds. The gaps on the sides (should) still allow enough air to flow to the radiator even with the blockage of the condensor. This is also why the raditor is behind the condensor.

Hope that sheds some light!

[Z2TT]

Hi, I will get pics of the insulation I talk of soon.

The fan, instead of running it via the high pressure switch, why not just run it constant when a/c is on, I allready have a small fan placed near the radiator at not the best thought out location (Later soarers relocated to better position), and that fan is controlled by a relay from one of the high pressure switches.......

The fan comes on at too high pressures, only function is to prevent dangerously high pressures, it was a while but pretty much if you block the condenser totally and leave it for a while, then it turns on, more of a failsafe fan than to improve efficiency. I have allready made this fan run constantly, helps a bit but it's location is not the best, more cost saving as I said the later soarer runs a different fan... I cant upgrade to that one as it requires hardline relocation.

Yes I had a manifold gauge hooked up, so i did a test and sprayed water over the condenser, high side pressures dropped and cooling got better, and in traffic it's bad, and when your going it gets better but not that much, as I got a front mount inter cooler which restricts flow a bit, definitely needs a fan which is why I'm out to put one in, and improve upon the existing design by insulating the low side pipes, like I said I will get a picture of the "tape" that is wrapped around it.

The condenser, do you mean internally or externally clean it? Outside it's pretty clean I'll still clean it more though, but I have had a previous compressor failure due to lack of oil (7 leaks is bound to do that), which are all fixed now and correct amount of oil is in now.

So the condenser definitely has gunk on the inside, in this case what should I use? Blow some thinners through it, or degreaser?
It doesn't have to be poofter perfect clean but anything that will get some gunk out is better than nothing.

Edit - Some pictures. As we see, the low side pipe coming from the firewall, then the low side hose that goes to compressor and it's insulation :



http://img25.imageshack.us/img25/7694/ins2o.jpg

http://img195.imageshack.us/img195/6514/lowhigh.jpg


Thanks.

[matty12]

Yeah thats not really insulation, more so wiring spiral wrap.

If its a serpintine type condnesor you have a chance to clean the crap out. Use shellite to do it and do it in a reverse fashion, so drier back to the compressor end. There would be no guarantee that yould get the crap out though.

[Z2TT]

It's a parallel flow condenser.

Yeah it's not really much of an insulation, not sure why they put it there maybe for abrasion resistance but the pipe pretty much doesn't come in contact with anything.
Any ideas for heat insulation for the hose, name of a material and where it can be found, something from bunnings?

[Rhyno]

Good stuff mate, seems as like you have done a pretty good analasis.

Matty your right, that is spiral wrap generaly used to protect electronic cables from abrasion.

In regards to your currently installed suction line, because it is where it is, and currently installed I would reccommend using some "foam insulating tape". Wrapping the pipe in a spiral manner, over lapping itself, working back to the firewall. A couple of neatly cut up strips will cover that hole in your fire wall, a help a lot with humidity control. The best bet would be to use some refrigeration pipe insulation, but as the pipe is installed, this is not possible.

In regards to cleaning your condensor, I ment externally. Cleaning internally is usually done with a flushing agent, at the time of repair. Best bet is to get some coil cleaner, preferable a type with a foaming agent (just helps "push" the grit out). Spray it on, wait 15 mins, flush throughly and repeat 3 times. This also works for radiators and intercoolers... You will be surprised at the amount of crap that will come out, and the change in the performance of the various systems!

These parts are commonly available from refrigeration parts outlets such as Heatcraft Refigeration, you should have them down there, pretty sure they are Australia wide. Let me know if you need help getting the right stuff Should get change from $50, the stuff aint that costly.

In regards to your current fan set up, any pics mate? Engine bay side and maybe a shot of between the intercooler and the condensor?

The only prob with running the fan constant is that you are costing yourself fuel, in the form of that the alternator will need to run more to power the fan - and lets face it - your still hot, so a soultion is required.

Im thinking, depending on your set up, possibly piss the standard cowl (if any) and fan off, and fit 2 fans side by side, controlled by a bi-metalic switch on your discharge line. These switches cost like $10 from Jaycar, and should solve all your problems.

On this note, when your Comp seized, did a new comp get put in, or a reconditioned one, or one from the wreckers? Did the system have a flush, to remove the broken bits of the compressor? And then a presure/vacuum test done before recharging? Do you remember any of the pressures from your gauges when you where doing your test?

Just wondering if you may have a small leak... hope not!!!

Sorry to ask so many questions, just trying to get a clear picture.

[matty12]

Im sure paralell condensor have little fins on the inside to improve effeciency of them. They tend to trap debris and arnt recommended to be flush out as it doenst normaly come clean.

You can run your thermo relay of the power wire from your compressor so the fan cuts in when the comp starts.

[matty12]

This double post bought to you by HTC.

[Rhyno]

Hi Matty,

I haven't heard that before however it is to my understanding that the coil cleaner I have specified is an anti bacterial solvent, specificly designed to break down dirt and sludge deposits.

Therefore, with this chemical I can not forsee any problems with the debris being trapped; as it will mostly be disolved (at least by the third time!).

Also looping a relay off your AC clutch ain't a bad idea, however when cruising along the highway your fan's will be running constantly, wasting power.

You may find that after a good clean of all the coils, there is ample air flow and another fan is not required, considering there are 2 large restictions in place all ready, the system may operate satisfactorly with the improved airflow through the various coils.

Had another thought: How hot does your intercooler get? The amount of heat an airconditioning (or refrigeration) system can regect is porportional to the amount of cooling that can be achieved...

At the end of the day, we ain't talking HUGE savings, but every bit counts.

But that's just my educated opinion, nothing more.

[mick08]

Hi Matty,

I haven't heard that before however it is to my understanding that the coil cleaner I have specified is an anti bacterial solvent, specificly designed to break down dirt and sludge deposits.

Therefore, with this chemical I can not forsee any problems with the debris being trapped; as it will mostly be disolved (at least by the third time!).

Also looping a relay off your AC clutch ain't a bad idea, however when cruising along the highway your fan's will be running constantly, wasting power.

You may find that after a good clean of all the coils, there is ample air flow and another fan is not required, considering there are 2 large restictions in place all ready, the system may operate satisfactorly with the improved airflow through the various coils.

Had another thought: How hot does your intercooler get? The amount of heat an airconditioning (or refrigeration) system can regect is porportional to the amount of cooling that can be achieved...

At the end of the day, we ain't talking HUGE savings, but every bit counts.

But that's just my educated opinion, nothing more.

On that note would a larger condenser coil be of no effect in rejecting heat if its only proportional to the amount cooling done, i only ask caus i been watchin this thread very closely and plan on fitting a larger truck condenser under the tray of my hilux.

[Rhyno]

Hi Mick 08,

There is some benefit of fitting a larger condensor to your vehicle, however fitting one too large can have its own problems. Do you mean larger in length, or larger depth?

There are quite good gains to be had from fitting a large or remote condensor, because the air passing through the condensor has a greater heat transfer, from the greater surface area of the coils and/or also the lower air temps. You will find that with a larger condensor, in theory your system should be more efficent, as it will have a greater temperture difference, up to a point.

In short, done properly, you WILL get lower evaporator (vent) temps, and a more economic system.

A general rule of thumb as I understand that if the condensor you are using has a slightly larger pipe diameter that the discharge (hot line) you should be ok, as you do not want to create to large of a pressure drop across the system as this will lead to problem. If the pipework is identical you should have no problems either, but will have to carefully monitor your AC system when recharging it to ensure the refrigerant levels are kept at acceptable pressure's.

So say for arguments sake you have a 1/4 inch disharge (hot) line, you would want the condensor to have a 3/8 inlet, for a 3/8 you would want a 1/2 condensor inlet and so on and so forth.

However, I would strongly reccomend talking to your refrigeration/airconditioning mechanic before making these alterations. There are severl issues to consider such as stone/rock damage to the coil, and the running of the lines (phsical placement) and whether your compressor can handle the extra pressure of pumping the refriegerant a greter a distance. My gut feeling is that you will be fine, but don't take my word for it!

Also there are other ways to get colder AC. When I was in my first year of my apprenticeship I picked up a old VH Bomodore that had a leak on the AC, and had lost all its R12. Found the leak, fixed it, changed the filter drier, and regassed her with SP34E, a drop in replacement for R12, legal, and a more efficent gas. You would not believe the difference! How about mist coming out your airvent's when its 33 degrees out side!

This is something I would discuss with your frigey, there are lots of options out there, all with their pro's and con's and different cost's.

Sorry Z2TT, not tryin to jam your thread up!

[river]

Hi,

The best protection for your condensor is a big fuck FMIC in front of it.

seeyuzz
river

[matty12]

On that note would a larger condenser coil be of no effect in rejecting heat if its only proportional to the amount cooling done, i only ask caus i been watchin this thread very closely and plan on fitting a larger truck condenser under the tray of my hilux.

good idea, most hilux condensors are too small and have quite high head pressures because of it, doesnt help either that it has a clutch fan. Often have to water down hilux condensor on mild days just to get the right temps out of them.

[mick08]

Thanks for the info guys, my hilux runs a 1uz-fe and it uses the orig compressor from the 91 soarer donor car, the reason i wanted to put it under the tray is i didn't want to block air from the alloy SR20 radiator i use, i also got a/c hose fairly cheap on a repco managers special so ican do it fairly cheaply plus, my cousin is an autoleky and can make the hoses up and gas it cheap. I found the condenser at work its from a Volvo truck,its not the biggest one i've seen but may be nearly twice the size of the hilux one, will get dimensions on monday.

[Rhyno]

You have a good starting point; I used to have a JZZ80 1JZ Soarer, and they have a farly large interior for a two door car, and as such have a compressor capable of cooling large heatloads fairly quickly.

Mick08 I checked your profile and you had your vehicle listed as a dual cab rn85 ute, which a little guess-timation, I assume your cabin is smaller, and you should have enough capacity from your compressor.

A Volvo truck condensor? Hmmnn may be a little on the large side, but should be fine, just be carefull not to overcharge the system, as you may end up with liquid refrigerant entering your compressor = fucked compressor. Keen see the dimensions of this beast, and the size of the connections... Im guessing your gonna have a 1/2 inch inlet and an 3/8 outlet...

At the end of the day if you can do it for cheap to have a trial, do it, test it, then look to protect the coil once testing is complete. I reckon some crim safe screen or similar would be the way to go.

Looking forward to your response.