View source for Some AC Q's Answered

<center>'''Some Air Conditionor Questions Answered'''</center>
[[Image:ac1.jpg]]<br>
<br>First things first, the basic cycle in your cars!! One to remember as Pressure increases temperature increases and vice versa as pressure decreases temp drops<br>
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== Compressor ==

Provides motive force for the Fridge gas. Pulls in the gas at a very low pressure (cold) and compresses it to a high pressure (V hot).<br>
- Lubricated in all Gen 5's by a fridge gas compatible mineral oil.<br>
- Belt driven from engine (uses about 2-4 HP)<br>

== Condensor ==

Converts fridge gas to a medium temp liquid by heat transfer.<br>
- To ensure heat transfer, air is passed across cooling fins aided by electric fan<br>

== Oil receiver/drier ==

Holds a majority of liquid refrigerent for system<br>
- Has a drier in the receiver to dry fridge liquid (water content)<br>
- Fitted with sight glass to ascertain fridge liquid level.<br>
- High side (high pressure) charging connection (schreider fitting)<br>

== Expansion valve ==

Rapidly drops fridge liquid pressure to give V cold temp in fridge liquid. 

== Evaporator ==

Fitted in cabin in vent system. Heat transfer takes place from cabin air to fridge liquid in evaporator.<br>
Refrigerant turns back to gas at alow pressure as heat transfer takes place.<br>

That's the basic cycle. here is where those bits are on your car!!<br>
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== How to run your AC ==
 
1. Always air in cabin on recirc.<br>
2. Fan speed to medium speed. If fan speed is set high initially refrigerant will pass across evaporator too quickly and heat transfer will be lost (cooling effect in cabin)<br>
3. Set temp to minimum<br>
4. Set fans to blow into faces of passengers.<br>
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== How do you keep your AC top line ==

1. Ensure evaporator is clear of all rubbish/leaves etc.<br>
2. Ensure all schreider connection caps are in place on charging connections<br>
3. If your not running your AC constantly then run up at least once per month (even in winter!!  ). This stops all seals from drying out and cracking. Personally I run my Ac all the time and control temp with the heater it makes a great de-mister.<br> 
4. Ensure all lagging around ac pipe passing through engine bay is:<br>
a. there<br>
b. in good state of repair.<br>

== AC common failings ==

1. Compressor seizure due to lack of oil (due to fridge gas leaks)<br>
2. Compressor clutch failure due to electrical problems with compressor clutch or clutch seizure (if AC system is not used regularly)<br> 
3. Incorrect belt tightness (normal to hear a squeal as well)<br>
4. Hole in Condensor due to corrosion or flying stones (loss of fridge gas)<br>
5. Seals leaking due to low use of system (or just old age!!) Primarily:<br>
a. Where hoses join onto suction and discharge of compressor<br>
b. Where hoses connect to condensor and pipe work connects to drier/receiver<br> 
c. Compressor pully shaft seal<br>
6. Hole in evaporator due to corrosion<br>
7. Incorrect charging procedure introduce air into fridge circuit. Small circiuts as fitted to cars will have untold damage inflicted to compressors or condensors if air is in the fridge system<br>

Obviously this is not exhaustive list but things I have come across whilst working on AC. 

== R12 Gas ==
 
As far as I know all Gen 5's that are fitted with Ac will have been charged with R12 (there is normally a tally on the bonnet edge telling you this!) 

As we all know R12 is no longer available although there are some stocks available that have not been used yet. 

Changing gas to R134A is something that is done however 134A requires a synthetic oil additive and in some cases major component change. The synthetic oil additive is what causes the damage to your o seals and rubber components. 

TALKING TO A MATE OF MINE DOWN HERE IN THE SUNNY SOUTHWEST HE CHANGES ALL R12 CARS WITH RS24 (NO NOT A FLASH DAGENHAM DUSTBIN!!). THIS GAS IS A STRAIGHT DROP IN GAS WHICH WORKS WITH THE MINERAL OIL IN THE GAS CIRCUIT ALREADY. 

'''How is this done'''?

1. AC circuit to be MT of all R12.<br>
2. System pressure tested to 14 bar (205 psi, car tyres run at nominally 30psi) using nitrogen gas.<br>
3. Once system is pressure tetsed and all leaks cured system is de-hydrated (all moisture removed) using a vacuum pump which takes the system to absolute vacuum.<br>
4. Vacuum is then broken with RS24 fridge gas and system charged with correct weight of gas.<br>

This can be done for around £85.00 (depending on your local garage/mechanic's labour cost's etc...).

== Spotting leaks ==

Not easy this:-<br>
1. Lot's of bubbles in sight glass (it's normal to see a few bubbles especially on hot days) and temp in cabin does not drop can indicate low fridge level.<br>
2. Oil leaking from compressor connections or pulley shaft seal.<br>
3. If you have had a really posh AC service some technicians put in a flourecsent dye to indicate leaks. Can only be seen under a UV lamp so not really practical in the motor industry.<br>

Hope this helps fellow members. I don't mean to teach anybody to suck eggs or baffle others with science so I picked a basic level I hope all will understand<br>
<br>''Note:''<br>

In very hot weather, a fair amount of water will drip from the overflow pipe on the engine bulkhead passenger side, and form a nice puddle under the car.<br>
This is perfectly normal.