Air Conditioning Tech Thread.

[Z2TT]

VS Actually had an "R134a" System from Factory I believe, all of them I've seen had a Parallel flow Evaporator i've never seen them with a serpentine unless this is talking VR?

I believe most cars today have a thermostatic cycling switch that would cut out at say 3-6 Degrees anyway so regardless of refrigerant once it reaches 0 it cuts out, or some at 3c etc,
I'm sure the VT would do this too? I guess one possible problem for cars that don't use Thermostats, with Hychill it in theory can get as cold as -5 Degrees for cars that use EPR Valves
as they would be set to allow Suction pressure to call down to say 30 PSI but not any lower in the case if the car uses an EPR Valve but not many cars do, I still don't think this is cold enough
to build up enough liquid in the evaporator and slug the compressor

Does the VT rely just on the Variable Displacement compressor to control vent temperature by letting less refrigerant circulate through the system (Less displacement/flow)..... the Climate Control unit
doesn't cut out the compressor at all? Would have at least thought Holden would make a failsafe. Wait a minute though, if anything doesn't the VT cool worse when the Control valve fails, instead of get
much colder? I haven't taken apart any of these compressors to see how they work but does the valve sieze at a certain point?

[matty12]

Vr vs uses parralell cond but sepintine evaps. Vt and many comp now days are variable displacement and run just like the old epr valves, if you keep the suction pressure constant no need for a thermostat. Normally when the valve fails you get no suction pressure at all, sometimes they don't destroke the comps ant they just run flat out and will pull down the suction beyond set point and freeze. Varying pump out put is better on fuel/environment and also better on the pump with far less shock load as they aren't stopping and starting all the time.

[Z2TT]

Yeah I would have thought they'd put a failsafe on the VT so incase something goes wrong then it cuts out because evap air outlet is too cold.

Come to think of it I remember my Soarer when it had a EPR Valve, it's Suction line would often freeze up on cooler days and definitely did not cut out, I actually never remember
that compressor cycling before. That is the only consideration needed to take with Hychill as far as system design goes, I'd say changing the spring in the EPR Valve will fix that,
in theory so long as the expansion valve is working well it should close up far enough not to fill up the evaporator with liquid and slug the compressor during low Load.

[matty12]

yeah soarers have and cressidas and alot of toyota stuff, even some 70's american/aussie stuff has versions of the same desgin. The newer stuff goes one further and destorke the compressor to save fuel etc.

How did you go on the FG?

[Z2TT]

I haven't gotten around to sussing the FG out yet. Unlike the BA and probably every other EFI Falcon, the FG Runs low speed fan mode for the A/C Always, so I thought this could be one of the reasons why.
I Jumped one of the relays to run it constantly on high speed, but vent temperatures did not fall a single bit, making me think that the Climate Control Unit is commanding some flaps to open and mix
heater air in, or mix exterior air in. Or that there is a problem that is stopping the condenser from rejecting more heat, such as overcharge. I'll have to organize to get a set of gauges on it next time and see how things go regarding the condenser cooling.

Next I will try clamp the heater hoses to shut off flow to the heater core, and check if there is any suction through the Exterior Air Vents.

Apparently there was a software update for the FG regarding the Flap mixing issue, but this doesn't seem to have fixed poor A/C Performance that everybody talks about, I mean it's acceptable, but not how a Falcon should be like, at times it's totally unnaceptable whether at other times mysteriously it works a bit better in similar ambient temperature and humidity.
high side pressures are way too high so the charge on this specific vehicle might be overcharged as systems like this using a smaller capacity and sub-cooled condenser would react negatively to overcharge, but that doesn't explain why everybody is saying the same thing about the FG. Condenser is Decent sized, I wonder if the evaporator is just too small on these cars or an Improper specced expansion valve from the factory, or perhaps a defective one.

Lastly, I'm having a look at where the Condenser is positioned, and whether it allows for enough airflow over it's fins, it seems the thermo fans in the FG might suck too much air around from the gaps and not through the actual core.

[matty12]

I lost count of the amount of times ive being charging one and next minute its overcharged, they have such a fine line between the two. I now charge a few grams and let it settle then a little more and so on.

There is a a/c diagnotics box for the FG(and also VE's) but as i havent had to do one yet i havent bought one and the fact that they are on the pricey side.

Do you mean low rad/condensor fan speed?

Yur gauge vs suction hose temp should tell you if your getting any heater blend. If the gas temp and pipe temp are within a few degrees of each other but your getting higher temps out your vents the a/c working alrite but heat is creeping in. Of course thats on if the a/c is working fine and theres not a low gas charge etc.

[Z2TT]

It's harder to tell with the FG as the Liquid line is Soldered/Mated to the suction line.... allowing the suction line to give extra cooling to the liquid line, I doub't it will make hardly a difference in the real world.... but the Suction Line temp is affected as the liquid line is exchanging it's temperature into it.

The easier way to test the heater blend would be with A/C Off to measure on Recycle the Inlet air to the Blower Motor, and vent Temp..... I did this Today and found 3c Different, perhaps the heater core may slightly be leaking in. Probably negligible?

More testing has been done. With the Windows down and forgot whether it was fresh or Recycle. I had now Sussed out the wiring Loom and Relay System and jumped the fan to what was medium speed (Left Fan High) (Right Fan Low)..... normally I think its both fans low. Vent Temp hardly fell and Head pressure fell 10 degrees. Then I jumped another relay which put both fans on full blast. Head Pressure quickly dropped from 250 PSI to 200 PSI. Vent Temp dropped about 1-2 Degrees. Now I forgot whether I was on Fresh Sucking hot engine heat in which would blurr results somewhat, or Recycle. However one thing, when I quickly went back to Normal Condenser fan Speed mode (Both Low)..... Vent Temp began to quickly rise, rose about 3 Degrees but at that point a Manifold guage hose coupler let go so the car was stopped.

All in all, about a 60 PSI Drop in Temperature on the High side was seen by activating the fans.

Next Step is going to be to ensure a correct charge is in, then do back to back testing with different condenser fan speed configurations, Next step will be to clamp the heater core water supply to rule that out as a variable, in-case the car is secretly opening the heater core flap.

So far , I can gather that head pressures are an issue in the FG Somewhat.

[matty12]

Man, really sounds like a overcharge. If its got heater blend it will work fine straight after first start up but when the car gets to temp it will obviously not. Ea- El falcon were real common for that, could never get much other than 10-12 degrees out of them. They were good for testing charge as you could get to all side of the TX to check for a full evap.

[Z2TT]

Definitely what I was thinking too, as vent temp doesn't drop too much compared to how much the high pressure side fell,
whether this is due to different factors or not, we will see in the next episode.

Next up is charge until optimal performance is achieved, then experiment with fan speeds and record pressures.

Apparently in the FG there have been some A/C Changes during the years around about 2011 before the MK2 Model,
And then apparently in the MK2 Model too.
exactly what they changed and why I have not found out yet.

[wa5]

Was talking to local A/C bloke today, asked about HyChill, His opinion was that it could leak out of systems due to having smaller molecules than 134a, any thoughts?

[matty12]

Was talking to someone else on a commodore forum and he mentioned the same thing that the gas seemed to dissappear, also mentioned the factory hoses weren't barrier hose, sure enough cut one open the next day and he was correct. Vt onwards.

[Z2TT]

Certain hoses on very late model cars apparently leak hydrocarbons out faster, there hasn't been any study done or reason given on this and why hydrocarbons would be more prone through leakage from these hoses.
I'd imagine if anything the poorer quality hoses would leak R134a at a faster rate to some degree too.

[PrettyCoolWagon]

So I left the A/C lines and compressor in the engine bay without releasing any gas But.. just found out the hard way 4AFE and 4AGZE A/C compressors are different.
Mounting bolt holes are different distances apart. Just hoisted 4agze into engine bay, got all excited thinking because the blocks are essentially the same, it'd be a piece of cake ..not so.. They use completely different mounting brackets.

So looks like mobile guy to come and de-gas, find a 4AGZE A/C compressor, fit it and get it re-gassed. (more $$$ I didn't budget for..)

Does any one know if 4AGE and 4AGZE'S use the same A/C compressor?

If the compressor will bolt to the 4AGTE, then you can leave it in the engine bay.

If it needs to come out, and you are environmentally conscious, then you can get a mobile guy to suck it out, otherwise...

[TERRA Operative]

Ah damn. I just scrapped a 4AGZE compressor last weekend........

[bikplaboi]

Hi Guys,

I am swapping the stock 18rc in my RA40 with a 1G-GTE and was wondering has anyone managed to get their AIRCON working after the engine conversion? What do you I need to pay attention to once the engine is installed?

Any pointers or advise would be great.


Thanks

Hi,

I've started up an Air Conditioning tech thread, talk about everything from retrofits, refrigerants, system components and troubleshooting.

In the situation shown below, what is the best place to put an electric fan to provide the maximum cooling for the a/c condenser?

Either in A as blow through or B as draw through?

Cons and Pros of each option?

Forgot to add it in, but the rad already has a fan behind it.



Thanks