R12 A/C regassing

[Z2TT]

Hi,

Just 2 good hints on car A/C that will be useful to many of you.

1. Before getting a re gas, check if your compressor is not siezed. One way to get a clue of the condition of your compressor is to spin the flange infront of the pulley. There should be a little flange in front of the pulley, try spinning this by hand. It should spin fairly freely and have no hard spots while spinning. If you are unable to spin this, then don't bother re gassing, replace your compressor first.

2. Its a good idea to replace your reciever/drier, as the desiccant inside is probably depleted, If you do replace this you need to buy new A/C O-rings for the Receiver/Drier.

[CrUZida]

The AC place should replace the dryer as part of the gassing if its more than a few years old.

[Tweak]

They wont begetting rid of r134a for some time. Its the most stable cooling gas they currently have thats affordable and easy to use.
r12 was phased out cos it was found that it gave you lung cancer
so the big rush to bring in r134a came in everyone retrined spent $$$$ only to discover 2 years leate this one gave ya ball cancer.
Using other gases which are ment for heavy industried will damage seals, pump, condenser and damge valves. As it will get lower then the working temp they can cope at.
Sticking lpg in is fucking Nuts. And the people who do it should be fucking stripped of their a/c ticket. It will catch up with then in the end.
QLD is becoming very strickt. All gas must be recored that is used or evacuated, Rego/vin of vehicle, Location eg where the car is going too. Determins the ammount of gas used, Health and Safety will do onspot check of all books with no notice given

[love ke70]

sounds like you know what your talking about tweak.
how much gas is usually used in a system?
and why is the LPG such a bad thing?

cheers, andrew

[river]

Hi,

My understanding is that on toyotas the compressor is not controlled by the climate control setting. The A/C is always set to maximum cooling, with the duty cycle being determined by whatever parameters stop the evaporator from icing over - usually a specific air temp on the outlet of the evaporator - and the desired climate temperature is controlled by adding heat (I have not seen one toyota setup that does not do this - A/C is either on or off).

I think you'll find on the older units they were controlled by a variable thermostat. I know the one on the RA25 has a slider temp controller to increase/decrease the cold. There is no connection between the air con and the heater to allow the heater to come on to reduce the cold. When the vehicle interior is at the set temp it cuts off, and then comes on again when the interior temp rises.

The air con in the RA28 has no slider control.. it just has an on/off button. But I am fairly sure it too has no connection to the heater unit, and when the vehicle interior is at the desired temp the air con turns off, then turns on when required.

Riverina's Vectra uses the heat to reduce air con temp... but this is a late model vehicle, which, as you say, may be the way they now control air con temp.

seeyuzz
river

[BrianRA23]

My understanding is that on toyotas the compressor is not controlled by the climate control setting. The A/C is always set to maximum cooling, with the duty cycle being determined by whatever parameters stop the evaporator from icing over - usually a specific air temp on the outlet of the evaporator - and the desired climate temperature is controlled by adding heat (I have not seen one toyota setup that does not do this - A/C is either on or off).

I know you are right with respect to my old Cressida, but I have found it to be not so obvious on my Landcruiser. The comment, told to me, was not directed at Toyotas. I have thought for some time about putting a variable control on the evapourator so that the AC cycles less instead of just adding the heat, but since the cruiser does not make it so obvious, duty cycle and load are down I have not felt pressed to add an extra level of complexity to the climate control system.

B

[cambelt]

Its just a simple variable thermostat that i use , adding a ajusting knob to a newer car does look a bit funny .
Dave

[Tweak]

The ammount of gas is different across most cars but generaly 400g, also you have to factor in the location and when the car is going to use it. eg if its going to NT then id add in an extra 50g so the system can cope witht he heat
LPG is bad, its highly flamable for starters, probly would fuck ya seals and contaminate ya oil. LPG is from mineral type background so i guess it would have fine particles suspensed in the gas

[BrianRA23]

LPG is bad, its highly flamable for starters, probly would fuck ya seals and contaminate ya oil. LPG is from mineral type background so i guess it would have fine particles suspensed in the gas

LPG is highly flammable, but we are (mainly) discussing an accepted hydrocarbon based gas designed and accepted for use in air conditioning systems. That said, I heard LPG worked amazingly well with the only negative being the flammability aspect, which lead to the development of the HR12 and similar products.

Not sure what you mean about the particles suspended in the gas, as there should not be any. I understand that it is the size of the HR12 molecule that is larger and less likely to leak, just like the difference between air or helium in a balloon where the Helium will escape much faster than air in the same conditions.

Dave, that is the same variable option as I was thinking.

B

[cambelt]

I think the sole purpose of HR12 is to offer the customer a cheap regas.
The propper way is to retrofit to R134a .
For a cheap regas its OK .
Dave

[Mos]

I think you'll find on the older units they were controlled by a variable thermostat. I know the one on the RA25 has a slider temp controller to increase/decrease the cold. There is no connection between the air con and the heater to allow the heater to come on to reduce the cold. When the vehicle interior is at the set temp it cuts off, and then comes on again when the interior temp rises.

Yeah, I forgot about that - some (very rare) AE86 versions had this as well - but yes, it's a variable thermostat rather than "climate control" although it does achieve the effect of adjusting the amount of cooling.
The earlier "A/C Amplifiers" have an internal pot for temperature adjustment - this pot can be quite easily brought out to allow external control.

The air con in the RA28 has no slider control.. it just has an on/off button. But I am fairly sure it too has no connection to the heater unit, and when the vehicle interior is at the desired temp the air con turns off, then turns on when required.

Yeah, on the older cars (and some not so old) the fan is controlled by the switch directly and the heater mechanically. Anything that has servo motors can have climate control but doesn't always.

Riverina's Vectra uses the heat to reduce air con temp... but this is a late model vehicle, which, as you say, may be the way they now control air con temp.

One of the reasons they do it is to dehumidify.

Its just a simple variable thermostat that i use , adding a ajusting knob to a newer car does look a bit funny.

I had thoughts of using the factory temperature setting knob to run a variable themostat, but at the end of the day it's just easier to not do anything

I know you are right with respect to my old Cressida, but I have found it to be not so obvious on my Landcruiser. The comment, told to me, was not directed at Toyotas. I have thought for some time about putting a variable control on the evapourator so that the AC cycles less instead of just adding the heat, but since the cruiser does not make it so obvious, duty cycle and load are down I have not felt pressed to add an extra level of complexity to the climate control system.

Ditto - it's just not worth it.
On the cressida the compressor is not cycled - it has a hydraulic regulator rather than electronic control. The later model higher end cars (soarer, crown, celsior, etc) all have the hydraulic regulation - not sure about the cruiser. On those cars you generally can't tell the A/C is on (unless you have a really bad 7M...).

I'm glad I'm not the only one who thinks adding heat is silly

Mos.

[CrUZida]

While adding heat is silly, to me its better than cycling the compressor on and off. I'm not sure how good it is for the clutch to constantly be disengaged/engaged while the engine is doing 2500rpm (and the compressor doing much more)

[Mos]

Doesn't the compressor cycle anyway?

[CrUZida]

Some cars may, but others have 12v directly from the switch (through a low pressure switch) to the compressor.

If I get bored I'll hook a light up to the compressor, see when its on and if it cycles.
If it does, then my argument above is null and void.

[Mos]

My question wasn't really a question
On cars with hydraulic regulators (not many), it doesn't cycle. On cars without hydraulic regulators (ie most) it cycles.

Your argument is null and void