Air Conditioning Tech Thread.

[TurboRA28]

Hey all, interesting topic and hoping to get a bit of advice..
I'm wanting to fit AC to an old 80's coaster bus with a 1uz (so has the compressor on the engine already).
I was looking at some external units like these - http://speedyairspares.com.au/produc..._Unit-2-2.html

Then fitting a evaporator and condensor from another car?

Opinions?

[matty12]

that includes the evaporator in it. Im no good and have never done any sizing for that sort of stuff but i think a unit like that would struggle to get any decent temps inside a cabin as big as a coaster bus.

From memory a coster has a front/ rear evap which is a quite large unit.

From the other page, what about a idle up solinoid, something like the anti deiseling solinoid the kingers v8 used to used to use just to nudge up the throttle when the compressor kicks in??

[Rhyno]

Hi Caam,

Sounds like your AC and your engine are in good working order except for stalling problem.

Hmmmnn you are correct, in an efi engine when the AC is turned on the ECU increases the idle to compensate, yet still obtain maximum fuel ecomermy when the AC is turned off.

What I would reccomend is looking at the wiring diagrams for the two motors and comparing the ac circuits. Im guessing there may be an extra component the 2TG has that the 3TGTE dosent have, as the 3T is fuel injected.

I will be honest with you. I am unsure what product to purchase to rectify this fault. Prehaps you could look into Matty 12s surgestion.

Hi TurboRA28,

That sounds like its going to be one awesome fun bus! Its good you have got that motor, it has been idicated that the comp on there the has quite high capacity.

Had a look at the evap/heater you where considering, but I would not commit to ordering anything without first having a look at your heat load, that is how much cooling is required to adequately cool your bus.

I can do a quick heatload calculation and reccomendation for you if you like. Just need to know a few things.

1. What is the bus to be used for? Just traverling, or will the AC get frequent stationary use e.g. camping, or doing the "deed" etc. etc.

2. How big is the bus? As in what are the internal measurements, L x W x H?

3. How many windows, all the way around? If they are all teh way around, what height are they? Will the windows be tinted?

4. What is the average ambient conditions (temperture) where the vehicile will be used.

5. How many people MAXIMUM do you intend to have "use" the bus.

Kind Regards,

Ryan

http://wrightservices.vpweb.com.au

[RA35GT]

that includes the evaporator in it. Im no good and have never done any sizing for that sort of stuff but i think a unit like that would struggle to get any decent temps inside a cabin as big as a coaster bus.

From memory a coster has a front/ rear evap which is a quite large unit.

From the other page, what about a idle up solinoid, something like the anti deiseling solinoid the kingers v8 used to used to use just to nudge up the throttle when the compressor kicks in??

The anti dieseling solenoid cut fuel to the idle circuit when ignition was switched off to stop it running on.

Carby cars with a/c usually have a solenoid that "presses" on the throttle linkage to increase the idle rpm.

[maccac__1590]

carbied cars that i have worked on have a small vacuum solenoid valve that has power when the a/c clutch is on and a small vacuum actuator that pulls on the throttle linkages somehow to increase the idle a tinny bit

[caam]

The solenoid idea makes sense, Does anyone know where it would be possible to find one too use? and how hard the would be too wire in?

Cheers for the replys

[matty12]

The anti dieseling solenoid cut fuel to the idle circuit when ignition was switched off to stop it running on.

Carby cars with a/c usually have a solenoid that "presses" on the throttle linkage to increase the idle rpm.

On the rochesters on blue motor 253/308's it bumped up the throttle when the igniton was turned on and that was were it would idle, when the ignition was cut it drop the butterfly completely shut.Thats what i seem to remeber anyway, it has been a while

Making a bracket to hold something like that seems easy in theory, im sure theres other ways of doing it but thats the one ive always had in my head to do it.

Im even thinking of possibly going down that route for the 1uz in my VL as im considering putting the a/c back in to that. The original stepper motor just seems to hard/ complicted to use.

[Z2TT]

Another Idea,

Could you make a thread on the inlet manifold and screw in a vac connection, then use a VSV to be triggered when the a/c turns on?

[dnegative]

Back again

Last year I went and fitted a reman compressor, new dryer, changed all the o-rings I could find and got a mate to charge it with r134a. Now, while it was huge improvement over winding the window down it really wasn't anything special. I kinda just accepted it as it seemed to do the job and moved on. Fast forward to summer this year and my AC has gone from somewhat cold to cool-ish, noticed there is a bit of oily shit around the fitting on the condenser so It's leaked a bit of gas etc. Decided I'm going to have another crack at it, I've nipped the fitting up a bit and I'm booked in ($130 I'm told) to get the R134a dumped for Hychill HR12 assuming the auto elec finds nothing wrong.

Anyone here have anything good to say about hychill or going from R134a to HR12? I'm assuming everything should be compatible.

[Rhyno]

Hey mate, sounds like you had a small leak right from the get go. Anyways glad to read you have found the problem.

In regards to the Hychill refrigerant HR12, it is a good bit of gear, just make sure your condensor is in good condition and clean. Hychill is an LPG based refrigerant, and is very efficent. Make sure your frigey changes the oil in your system as they are different from the requirements of R134a and HR12 - also make sure he changes your filter/drier, so you have a nice clean system for the HR12 to drop into.

Would be good to see the results.

[matty12]

what sort of vehicle again??

just double check the oring joint, if its not a pad fitting type join on the condensor the fitting can have a tendency to split so changing the oring wont fix it and make sure it gets pressure tested before its recharged. I for what i remember have never realy had any issues with R134a into R12 systems not working etc. Its possibly that they also maybe other issues at play like heater blend/ externally blocked evap etc not giving you good vent temps, if its cutting on thermostat changing gas wont make it colder. It will be good to see a comparson though.

[Rhyno]

Good call Matty on the condensor joint and pressure testing. Where is that Rep button?

While your at it ask if your mechanic does a vacuum test, unlikely but its another great way of ensuring your system doesnt leak and that your ac system is free of contaminants. (oxgen and moisture)

[dnegative]

I had a bit of a chat to the guy about it, he was of the opinion that for R12 systems it performs better and is colder. I'm guessing he will be looking for leaks as he quoted me on the basis that everything was ok. The AC system is not the greatest in the AW11, condenser is in the front and at speed air gets trapped behind it as there is no engine bay for air to flow into etc

I'll find out tomorrow

[Rhyno]

Most auto shops that do mechanics don't do any testing besides hooking up a vac pump and listening to if it changes noise, which indicates (pretty much nothing) that the pump is attemping to pull a deep vacuum.

There should be no problem with having the AC up there, its actually great for rejecting heat as there is no radiator or intercooler blocking heat transfer... on the other side the compressor has to work a lot harder to pump the gas all that way... so switching to hychill should be a great move considering that, as it should flow better due to 2 reasons; Hychill only requires a 1/3rd of the refrigerant charge compared to R12/R134a (less friction on the pipework), and it has a thinner molecular structure, meaning it has the benerfit of having less pressure drop through bends and turns.

BTW, pressure testing not only checks for leaks, it also helps clean the system as dry nitrogen is used, which helps absorbs any moisture inside the AC.

Would be really good to hear the results dnegtive

[matty12]

Most auto shops that do mechanics don't do any testing besides hooking up a vac pump and listening to if it changes noise, which indicates (pretty much nothing) that the pump is attemping to pull a deep vacuum.

Which shits me as the system only ever runs in pressure, not pressure testing means other than charging with dye and sending of means you dont really no if yourve fixed anything. I just had a customer come in yesturday that had a compressor/ condensor and evap changed looking for a leak, the customer beleives it was never tested. One test and within minutes i could hear it leaking and was a hose that was porus. If that was done in the first place it would of saved the customer a large chunk of cash.