A/c Dead

Im yet to see a S1.5 with R134a John, really I am....

An interesting challenge now... can someone proove me correct with a car?


Paul

Thinking about it i think i will stay with 134a, having a a/c system pressurised with propane may not be too much of a good idea when mixed with the electrical systems of a petrol engine in the event of an accident.

D

Apparantly the only ever case of fire/explosion caused by refrigerant is .............................. R134a !! You see it's the oil in the system that's the flammable bit. You have about 1kg of 134a in there versus 300grams of HR12.... It would be almost impossible to get the right mixture of gas/air for it to ignite. If you search for "explosion" the only reference you will find is some guy that throws these gases into a sealed up car and demonstrates they can't be ignited ..... Well he actually managed to ignite one after doing it for years (I think it's called natural selection).

Some cars are carrying 80litres of high octane fuel in a plastic fuel tank, 80litres of propane in a cylinder in the boot.... somehow 300grams in the air-con just doesn't phase me

seeya,
Shane L.

the risk is low granted and yes i do have plastic tank too, but the fuel tank aint in the cabin, like the condenser and a propane escape expanding 1600times from its liquid state into the cabin isnt something you want, being a smoker at least refrigerant is harmless, unless you inhale it through a cigerette .................wouldnt have a propane tank either, LPG will explode petrol just burns all be it rather violently.

D

Conversion of CITROEN R12 Air Conditioning System.
(extract from Air Conditioning All types - publication BRE 0368 GB Oct 1997).

The use of CFC12 (R12) fluid in automotive air conditioning systems was banned under International legislation drawn up by the MONTREAL protocol. Initially new installations were banned from 1993 then a few years later a prohibition on recharging existing systems with R12. At the time the only approved automotive replacement fluid was HFC134a (R134a).

Only vehicles manufactured before the 1986 model year may continue to use R12 refrigerant.

The ban on recharging existing R12 systems posed a number of problems:
* the materials used in the R12 circuits are not generally compatible with R134a,
* the compressor lubricating oil R12 is not compatible with R134a refrigerant,
* the R12 seals are not compatible with R134a refrigerant.

To avoid confusion a system upgraded to R134a must be fitted with R134a labels and the R12 threaded valves must be changed to R134a clic-fit type valves (note that the diameters of the high and low pressure valves are different to avoid the possibility of operator error). The R134a compressors are marked with a label which specifies:
* the type of compressor,
* the type of refrigerant,
* the nature of the lubricant to use.
The compressor inputs and outputs have clamped connections not threaded.

Precautions to be taken when opening the circuit.
Plug all piping quickly to prevent the entry of moisture. New parts should be at ambient temperature before unpacking to avoid condensation. The plugs in the component unions must be removed at the last moment before fitting. The dehydrator reservoir must not remain open to the air (even connected to the circuit) for more than 5 minutes because it risks being saturated with moisture.
If the circuit is left open to the air, it is necessary to replace:
* the dehydrator reservoir,
* the compressor oil.

Compressor
Vehicles equiped with R134a air conditioning can be fitted with two different types of compressor:
* fixed capacity (example SD 7H13) - oil type SP20,
* variable capacity (example SD 7V16) - oil type SP10.
Imperative: do not mix oil types.

Pressostat
The pressostat activates the high speed operation of the cooling fans:
* R134a air conditioning - 17 bars,
* R12 air conditioning - 19 bars.

Dehydrator Reservoir
The nature of the dehumidifier used with the R134a refrigerant is different to that used with the R12 refrigerant. Dehumidifier reservoirs compatible with R134a refrigerant are marked with a label.

Contents of a conversion kit:
* dehydrator reservoir,
* pressostat,
* identification sleeves,
* label,
* set of seals.

Notes:

There are earlier (BRE 008887) and later versions (BRE 0882 GB) of this conversion publication but I think this one covers the conversion process best.
I also have copies of:
* briefing on air conditioning checks and diagnosis - BRE 0445 GB,
* air conditioning principles & service operations - technical training workbook.

Most R12 compressors also have a bearing bush that is incompatible with R134a and requires changing.

The volume of R134a gas needed to run a R12 system converted to R134a is only 85% of the previous R12 volume if and only if the new lower BAR rating pressostat is fitted. Leave the old R12 20 BAR pressostat in place and you will need at least 4 times the volume of gas and will stress the system seals way beyond their normal operating range.

John

This post has been edited by xmexclusive on December 29, 2008 07:41 pm

XM Air Conditioning - Facts and Figures

Temperature checks:
Position the air conditioning controls:
* maximum cold,
* air blower at maximum speed,
* air distributor - open all the ventilation flaps,
* air inlet flap control - exterior air,
* put vehicle in a sheltered area (from wind, sun etc),
* boot closed,
* doors and windows closed.

Average Temperature of the airflow from the central vents

1. Fixed Capacity Compressor - R12 refrigerant or R134a refrigerant
Ambient temperature - Vent temperature
40 degrees C -------- less than 20 degrees C
35 degrees C -------- less than 15 degrees C
30 degrees C -------- less than 10 degrees C plus or minus 3 degrees C
25 degrees C or lower ----- less than 5 degrees C plus or minus 3 degrees C

2. Variable Capacity Compressor - R134a refrigerant
Ambient temperature - Vent temperature
40 degrees C --------- 24 degrees C plus or minus 3 degrees C
35 degrees C --------- 18 degrees C plus or minus 3 degrees C
30 degrees C --------- 15 degrees C plus or minus 3 degrees C
25 degrees C --------- 13 degrees C plus or minus 3 degrees C
20 degrees C --------- 10 degrees C plus or minus 3 degrees C
25 degrees C --------- 8 degrees C plus or minus 3 degrees C

Visual Check - Air Conditioning Circuit

1. Engine Stopped

Check the general condition of the refrigerant hoses for:
* split or cracked rubber,
* pinching or abnormal bending,
* faulty mounting.

Check Compressor drive belt for condition.

Dehydrator reservoir - moisture indicator:
* colour blue = filter correct,
* pink-coloured = filter faulty (humidity).

Engine cooling condenser and radiator - check for obstructions/debris and clean.

2. Engine Running

Dehydrator reservoir - fitted with a transparent bulb to check the refrigerant:
Condition of the refrigerant----------------Diagnosis
*Transparent refrigerant---------------Circuit correctly charged OR completely empty,
*Presence of bubbles in refrigerant---Lack of refrigerant in the circuit,
*Milky appearance of refrigerant------Presence of humidity in the circuit,
*Traces of oil in the refrigerant--------Too much oil in the circuit,
*Appearance of lines in refrigerant----Presence of desiccating salts in the circuit.
Note: for a variably capacity compressor, perform the check at maximum capacity otherwise the lack of bubbles does not mean that the amount of refrigerant in circuit is correct.

Refrigeration compressor clutch - switch the airconditioning on and check that the compressor clutch engages. If the compressor is visible then watch clutch for centre engagement and revolution. If hidden listen for clunk as clutch engages.

Interior heater blower - check operation.

Recycling - check the operation of the air inlet flap and remove the dead leaves from the air inlet grille.

John

This post has been edited by xmexclusive on December 29, 2008 07:31 pm

Thanks Xmexc, the garage said they had to do the conversion and they changed the dehydrator/drier but if the seals came in the kit then they should have changed them aswell, there is no label to say it is now running on R134a though or any identification sleeves, whatever they are. This info gives me a lot to work with, and im starting to think the A/C system may not have had the conversion done properly which could have caused damage .

D

Hi Dean

That was just what I thought were relevant extracts from the publications I could find to hand in the pile on the desk that I sorted out a while ago from a job lot I bought. If you need more detail then I will see if I can sort you out a full photocopy and also see if I can find anything else relevant.

John

Thanks, getting it tested will be the first step and will see what that throws up.
The problem is, if the conversion was not done correctly, i will have no comeback now because it was too long ago and Lucas done it! and they have just gone under

Regards
D

This post has been edited by dean on December 29, 2008 10:21 pm

Hi Dean

I guess the most important thing is to check that there is residual pressure in the aircon system. Just above atmospheric pressure will keep air and moisture out and prevent anything deteriating further. The worst possible option is to vac it down find it is leaking and then leave it for a while to suck moisture in.

John

Good point, i will have a check why the clutch isnt coming in and if there is any pressure in it at the weekend when i have some light and also track down a good mobile auto A/C specialist.

D

Hi all

The sight glass in the drier has nothing in it but there are a few small beads of condensation in there so the level has dropped?, thinking about it they took the car in and had it for 4 days because they stripped it down and had the wrong parts ordered so it may have been left in bits for days or opened repeatedly and moisture has become trapped in there somehow, there is pressure in there, i cant tell how much but definitely above atmospheric.

D

Hi Guys,

You can't just change over to R134a... They need to change every seal, the old seals will soon leak if not changed. The whole system must be flushed, the oil used is very different and not at all compatible. The Receiver dryer is always changed if the system is opened, and must be either way as the desiccant needs to be different. I reckon R134a is a sh!t gas, I wouldn't be converting, just use a hydrocarbon refrigerant. It will use any oil, go over any gas.. You can top up R12 or R134a with it, and it works better and runs lower pressures.

Have they converted it to the quick release R134a service ports? This is probably the way they expect people to find it's on R134a. Your receiver drier will need to be replaced either way if you need to open the system and change seals .... etc... The viewing glass means nothing with R134a, if the pump isn't running, short the pressure switch, if the compressor starts, it's low on gas and needs any leaks fixed and new gas added... DO NOT leave the pressure switch shorted, you will damage the pump !

Since I repaired the air-con on the XM here, and dumped a dose of HR12 in it ... Bloody thing is fantastic, it blasts huge quantities of cold air from both the front and rear seats vents !

seeya,
Shane L.

The charging point has a blue screw on dust cap over what looks like a deeply recessed schrader type valve only slightly larger.
I shorted the plug and the pump cuts in so i have gas going awol somewhere.

Thanks
D

This post has been edited by dean on December 31, 2008 06:09 pm

There isn't that many seals in the system to change actually...

Two to the evaporator, two to the dryer, two to the Rad at the front, and two BIGGER ones on the compressor...

When I put R134a on my 1993 R12 equppit V6 SEi, I changed the compressor, dryer and Rad along with the pipe work from a later car, and got a set of seals from the stealer... if I remember right, the 8 seals were only about a fiver...

For a Fiver I think its well worth putting a new set in... that eliminates seal leakage, and has to be either a pipe or rad, or evaporator, as Shane found...

Rgds
Paul

Thanks Paul, that may well be worth the outlay like you say as the unions to the pump where a little oily when i checked yesterday so they must be weeping slowly, not a big job at all by the sound of it either, will order a set when i get my rack kit next week.

Thanks
D