Wrong gauges

[charlie25]

Advice sorted, wifes getting on my case to sort out the car air con. Getting r134a couplers dropped off Saturday morning thing is I've picked up the wrong gauges from work r404, r407 and r22 would I be right in think that 20 to 25 psi would be okay on the low side evaporating at minus three to four?

[james10]

sounds good to me, you need to be careful not to overcharge the system, auto compressors dont take to kindly to liquid

[charlie25]

Champion, no I intend to decant if there's owt left pressure test with ofn, vac the system and re charge using scales. Cheers Marra.

[Tayters]

Hi Charlie,

Feeling your pain. The AC has been broken for months on our car and no radio as it got nicked. All in good time I tell her!
All the cars I've worked on evaporate about 30psig (SST1*C) and discharge 140 - 180psig depending on condensor fan cycling. Air off between 2 and 10*C depending on make of car. Some models always seemed to cool better than others. Never seen one evaporate below O*C but hey, it's been a while.
Watch out for the pollen filter. Probably buried under the wipers or behind the glove box.

Cheers,
Andy.

[mikeref]

Depends on engine revs and type of valve feed. Also, if you have variable displacement compressor, then it gets a little tricky. I charge vehicle a/c's at around 1200 rpm, which generally runs a suction pressure of 15 psi if ambient is above 20 C and air temp out of supply vents is say, 8 degrees C on medium fan speed.. Mike.

[charlie25]

Cheers lads will try in the morning and hopefully get a bit piece and quiet and maybe a beer or two

[Tayters]

Should be a sticker with the charging weight to make it easy anyway. Anything other than the pressures mentioned in the thread then looks like the beer is staying in the fridge!

Cheers,
Andy.

[texas64]

Weigh the charge in...Look for label under the hood(bonnet, right) which is the auto manufacturer's factory charge. Hope this helps.

[tbirdtbird]

I charge to more like 30 psi low side at 1500 RPM which is what most mfg advise. A factory manual will have the recommended charge as well as a table of low pressures vs OAT. I am surprised a suction of 15 gets you any cooling at all. If there is a sight glass on the receiver you are golden and can charge slowly until it is full. Trouble is receivers are going away and accumulators are in for some reason. A car AC comp won't do much below 1500 RPM

[charlie25]

Thanks to everyone 30psi did the trick and I'm in the good books with our lass so she won't mind me going to Leeds on Sunday to watch the toon.


Cheers

Charlie