134a pressure I have a DS35 dryer I want to know what should the 134a pressure be

Refrigerant HFC-134a or R134a
Weight 330 - 390 gms
With correct refrigerant:
Low side pressure 1.5-2.5 kg/cm2
High side pressure 14-16 kg/cm2

As far as I know you only have to change the compressor and dryer-filter to comply with 134a. Other components from old Freon 12 are safe to use for 134a. There's an Urban (mechanics) legend that you can use a 134a to an r12 system, but you can't use an r12 to a newer 134a system. But be on the safe side, change the compressor and dryer to use 134a or ask an expert on refrigeration.

start with checking a/c pressures is compressor cycling? does it have electric cooling fan? it should come on with a/c. usually there is a low limit/high limit switch. if pressure is low, say below 22psi @ low side port, switch will cut compressor. A quick electric "jump" of low limit switch will confirm clutch,compressor operation,but if pressure is low you may want to add freon. know your a/c system r-12 or r-134a,iv'e found converting to r-134a cheaper than purchasing r-12. r-134a takes a special pag oil and should not be used/mixed with ester oils. i could say more on subject but that's a start,of course always wear safety glasses and approach high side port with caution,which most newer cars don't have. thanks

you need to buy a recharge can of 134a that has a gage and hose attached, your a/c will not work if there is not enough pressure in the system. buy one of these recharge kits at your local auto store they run about $25.00.follow the enclose instructions on how to use it. Again if there is not enough pressure or if the system it is over pressurized than the compressor will not operate. by having the Gage you are going to know exactly the pressure of the system.Make sure you get the kit with the 134a and sealer in one can recharge kit.

Hi, the low pressure port is along the line that goes from the firewall to the compressor. It may be on the dryer, if there is a dryer on that line. The port usually has a black cap screwed onto it. I will look for a picture. Do you have the 3.0 engine?

The low pressure lines are larger. Follow the larger line from the compressor to find the low pressure port.

If it leaks 134 it will leak R-12 .I have changed hundreds of systems over to 134 without any complaints. Don't let the 94% eff rating of 134a scare you because that does not mean that your ac system will lose 6% cooling ability .A large class 8 truck or maybe a high roof van black on black and poor insulation might tax the system in the 90% range on 100 degree days but most systems never get close .
134a high side pressure will be about 18% higher so most systems you need to change the high side cutout.The R-12 electric fan switch will be ok just make sure it is engageing the fan when the pressure comes up.You must check the condensor in front of radiator to make sure air flows easily thru it.On systems where the hoses screw on each side of the dryer I replace the dryer .Drain oil from compressor and replace with 134a oil .Replace that bad valve core (with ac valve core not a tire valve) Now very very important vaccum the system and if no loss of vaccum in 20 min charge with manufactors recomended amount of oil and freon.If a system is low on freon (cycling in & out on low pressure switch) you can add a pound of charge with those small cans of same type freon no problem but when there is a leak and the charge has been lost or changing freon types you must pull a vaccum to properlly charge the system. If you just charge R-12 or 134a your system will have traped non -condensables and a large drop in cooling ability. Hope this helps. Harold

you will need these with guages

http://images.google.com/imgres?imgurl=http://bernardembden.com/xjs/134/charging.JPG&imgrefurl=http://bernardembden.com/xjs/134/index.htm&h=375&w=500&sz=31&hl=en&start=35&um=1&tbnid=OTaUQwB9xk9qRM:&tbnh=98&tbnw=130&prev=/images%3Fq%3Dcharging%2Bauto%2Ba/c%2Bunit%26start%3D20%26ndsp%3D20%26um%3D1%26hl%3Den%26safe%3Doff%26sa%3DN

how too link ^^^^^

E36 (1993+) A/C Condenser Replacement & System Recharging Procedure

DISCLAIMER:
It is illegal to vent R-134a in to the atmosphere. If your car has residual R-134a in the system, you must take the car in to have it professionally evacuated. Legalities aside, R-134a is toxic! Wear gloves and eye protection when dealing with this stuff. Note, this procedure is for R-134a cars only! This means 93+ E36s. I am not responsible for anything. Below is an account of how I did it and it may not work for you …

Ok, disclaimers aside – this job is easy. I mean really easy. Just be careful. There are a lot of steps though …

SITUATION:
I bought my ’93 E36 with a busted condenser as diagnosed by a dealer. Didn’t care at the time, Sandy Hago has great weather (especially where I live) . Anyway, I saw a condenser on ebay and decided to pick it up. A couple months later, I was ready …

DIAGNOSIS:
If your system has pressure in it, get it evacuated professionally. There are many shops that will do this and even tell you where your leak is (they use a die and a black light). My car had no pressure in it, so this step didn’t apply to me.

STUFF YOU’LL NEED:
1. A/C condenser (used, oem doesn’t really matter that much). Expect to pay less than $150. Dealer price is $450+
2. A/C receiver/dryer (oem). Ebay has ‘em for about $45. Dealer price is $125+.
3. Gaskets. Refer to the following picture for which ones. Caution! The ETK is wrong (at least for my car) on this. The dealer was also wrong. Overbuy if you must. About $40 (I know, what a rip). I ended up getting 4 #6s and 4 8s.
4. Manifold Gauge set for R-134a. Should have a blue gauge and hose (low pressure), red gauge and hose (hi pressure) and yellow hose (refrigerant supply/vacuum). About $75-$100.
5. Vacuum pump (oil based preferred). Don’t know where to get one. Maybe it can be rented. I borrowed one from a friend. They run for $250 I hear.
6. 3 cans (12oz) of R-134a and 1 can (8.5oz) of refrigerant oil. Available at any parts store. Total cost = $40.
7. Usual set of tools – Philips screwdrivers, hex sockets, ratchet.
8. six pack. I hate American beer, Rolling Rock is an exception though.
Total (if you buy everything) = $(150+45+40+100+250+40+10) = ~ $640.
Total (if you know someone with a pump and manifold (or rent)) = $(150+45+40+40+10)= ~ $290
Total (if you’re lucky like me ) = $(85+$40+$25+$30+10) = $190 (ebay – condenser/receiver-dryer, friend had the pump and manifold, gaskets – I know the parts guy at the dealership, kragen sale on R-134a and oil)
Total (dealership) = $1000+ !!!

on most vehicles, there is a high and low pressure side. put the guage on the low pressure side closest to the accumulator/dryer and your freon to the high side closest to the compressor. dont overfill.

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