Had a guy round last night to re gas the system, he did the usual, emptied the R12 (600g)?? took out moisture, put in R24, after everything was sorted the guages were reading fine, but the output was not cold, 30deg.

 

As the gauges were reading okay, he couldn't diagnose the problem with his big book!!

 

Any one got any ideas?

 

Rich

IIRC there are modifications to made for the air con unit to accept the new gas

 

Do a search on aircon regas, there are plenty of threads about the subject

 

Cheers

Graham

Graham

 

Thx

 

Found plenty of threads but none that speak of changes necessary to accept new gas.

 

I'll keep looking and try some of those diags on the aircon switch

 

Rich

Im not that experienced with aircon, but as far as Im aware its just the valves that need to be replaced to accept the R134a gas can. This would have been done and would not affect charge temp.

 

Might be worth PM'ing Funkyboogaloo, Im sure he works (or used to work) in the aircon trade.

 

However the fault may not be related to the aircon recharge, but could be a temp sensor failure within the aircon system or a stuck temperature valve.

Thanks LG, Thats what the guy sort of said, his gauges were reading okay, so he could only suggest some other part was causing the problem.

 

I'll gen up on the AC this week and have a bash at fixing it.

 

Cheers

 

Ric

To recharge the 300zx R12 a/c system with the newer R24 gas, needs adaptor fitting to the charging points. If your system was recharged with the R24 gas you must have had these adaptors fitted.

HTH

Dont think he put an adaptor on...

 

I'll give him a call and find out

 

Ric

Dont think he put an adaptor on...

 

I'll give him a call and find out

 

Ric

 

The R24 regas tubes will not connect onto the R12 connecters, if he didnt fit a set of adaptors then you must of had some already fitted.

a lot of guys fill with there own adaptors..did he fill the high pressure and low pressure lines

also if the filter is dirty it will not send could air in?

Acording to my neighbour he does comercaile fridges , the r24 gass is beigin superceded again in the next coulple of yrs !

Typical..Well i better get it working before the gas becomes illegal!!

I have these same import connectors. A local guy came and regassed the car with R134 gas, it seems all fine now - no mods were done and he seemed to know his stuff :)

Okay, resurrecting this post, i have not been able to sort out my air con, so, does anyone have any diagrams of the 300zx air con and as i'm stupid, a quick lesson in aircon workings.

 

I might be able to sort it out myself then.

 

Ric

Do a search for air con, im sure i wrote a huge in and out about it all that people didn't read LOL. I dont really want to do the same again.

Just found it, it was a thread started by Dougal200 but for some reason I cant post the link sorry

I'm hoping the bloke didn't put the recommended volume of gas in that was stated for the R12. Apparently the new gas expands much more than the old, and only approx 75% is needed...too much gas will result in no cooling even though it will still go through the motions!

Here you go mike

 

"Heres a copy of something I wrote a while ago on another site

 

OK heres the rub. Lots I dont know but car air con I do. In simple terms. Old cars (pre 1994 ish) R12 refrigerant (now illegal) and schraeder type valves with a non compatible oil. New cars (post 1994) R134a and quick release fittings with PAG oil.

Even if you change the fittings you can't just put R134a in the system for two reasons. 1st it runs at a higher pressure (pressure also directly relates to temperature) so the amount of refrigerant installed must be reduced. Also the old old oil will not mix with R134a so will starve the sytem of vital oil and seize the compressor.

So the way to do it properly is

Recover the R12 and dispose of properly.

Remove compressor and drain oil. Re-fill with an esther oil which will allow any remianing oil to mix with the new refrigerant and keep components lubricated, re-fit compressor.

Fit new quick release adaptors

Re-fill system with 30% less R134a than it would normally take in R12

Check for leaks

Hey presto done"

 

I thank you

Thanks guys, I think i saw that post Funky , so thanks. Looks like im on my own, which means replace every part till it works...or just leave it as is..which is more likely.

 

Ric

Quick question everyone, if my compressor was fubar would that cause my problem?

 

ie some cool air and some warm air..

 

Ric

What I cant understand is he said his gauges were reading OK. But if his gauges were reading ok you would have cold air! With the system off the pressures at the gauges would be equalised and relevant to the ambient temperature. When the system is running and the compressor is clutched in the low side will run at around 30-45psi (dependant on ambient and many other factures). Pressure is directly relative to temparature so if it goes too low the evaporator will freeze up. The high pressure side runs much higher pressures again dependant on many factures. So all I can guess is when he says his gauges were reading right that it was equalised and the system was holding pressure.

In which case then the first point must be to check that the compressor is "clutching in), this is easy simply start the car with the AC off, open the bonnet and ask someone to turn the AC on whilst you got your head under the bonnet. look at the end of the compressor and see if the clutch pulls in (its magnetic and is switched when you call for cold). If it does and the gauges still say exactly equal the guts of the compressor are knackered. If it doesn't check the fuses and relays and try again. If it still doesn't put a 12 volt live feed to the compressor and see if it clutches in, if it doesn't the clutch is knackered.

Thats your first starting point, come back when you've tried that.

Below is a brief diagram of a system. This is how it works

The compressor compresses the gas to a liquid (the high pressure side)and pushes it through the condensor (condensor is in front of the rad) and then through a drier, it then goes thru a TXV or OT, as it goes through there it goes into vacuum and into the evaporator, this drop in pressure causes the liquid to turn into a gas by "boiling off" taking the heat from the surrounding area as energy, the fan then blows the cold air around the car. And then rinse and repeat

Funkyb....etc

 

You're a star, you've given me something to go on, i'll do the checking over the next few days and get back to you,

 

As for how it works, well what can i say...no wonder it falls over!!

 

Once again Thanks

 

Rich

Funky

 

Couldn't see the compressor, but when the AC was turned on, i heard a clunky click, would this be the compressor? and if so would it indicate it was okay?

 

Rich

Yes sounds like it. So if the compressor is clutching in then the clutch and controls appear to be ok, so next step is to see if you get any temperature drop at all in the cab. Put it on full cold, med fan and centre vents. You should get anything around 6deg at the vent any lower and it may freeze at the evap. Up to 10deg at the vents is acceptable on an old car with change of refrigerant.

If not a couple of things could be wrong.

1. The guts of the compressor are shot and its not compressing

2. you have a blockage before the TXV not allowing refrigerant into the cab

3. Electronics are up the duff and not sending the right signals.

 

So 1st port of call is to let the system run and see if the clutch cuts in and out regularly (anything around 30secs intervals). If it clutches in and out much quicker than that it is likely you have a blockage or insufficient or excess gas in the system.

Make that your next test.

Start the car again put the system on and time the clutching in and out (the clunking)

Mike

Also check to see when the auxiliary fan cuts in.

Cheers Mike (better than calling you funkyb..)

 

Rich