OK, it's time to charge the AC for summer. It is still an R12 system and I have searched the forums and looked under the hood. There are 2 ports on the back of the compressor but they are not apparent which is high and low. One is marked "S" and the other is marked "D". Which one is low side? Thanks.

 

S is the suction side and the low port. The D is the discharge port which is the high pressure side. You are lucky you can still get R12

 

Thank you. I'm converting to 134a, but still needed to know which is which.

 

the R134 conversion kits consist of all new o-rings, new orifice tube, new dryer/reciever, and r134 fittings... I'd have to go look, but I think the fill port on my converted 740 is on the dryer/reciever

 

Yep you're correct but you can fill it from the compressor also.

 

Going to bump this old post.

I have a 90 240 on R12 as far I know. Reading this post I understand the S label on the compressor is the Low Port. Seems odd as the low port is not very accessible to charge the system. I purchased some Enviro-Safe that I'm going to give a try. Am I missing something on the low port?

 

The one marked "S" is the low port. On my '89 240 I found that taking off the air duct between the MAF and the throtle body gave good access to attach the hose from the fill kit. Put the duct back on to run the engine and charge the system, then remove duct to pull the kit hose, replace duct, good to go.

 

Coming back to this post as I didn't find too many details for DIY on 240's.

Helpful link on capacity details -

Volvo Refrigerant and oil capacity charts || TechChoice Parts

 

Pierce do you know if Enviro-safe can be used in a system that may have some remnants of R134 left in it? In other words, is it OK to mix them?

 

If you already have a car that uses r134, why use Envirosafe? I use it in my '92 which is r12 and it works OK--I do it because I am avoiding the conversion. The cost of the 134 and Envirosafe is almost the same!

 

Are you sure? I've seen 6 bottle packs of Enviro-safe on Ebay for less than $40.00. 6 cans of R134 would cost me a lot more and supposedly it's not as efficient, meaning you use less. But just to humor me, can it be mixed? And on your car did you have to add oil also?

 

No you cannot mix the two. The problem is the oil in the compressor. You will contaminate it and ruin the compressor.

 

what worked for me ...

I believe my system was empty. I added a R134A connector from Autozone (one in EnivorSafe kit did not work) used a gauge that I had which read zero. I then used Harbor Freight vacuum pump for about 30min and yes should have done it longer. Note you should remove the MAF and hoses to make job easier. Then added one can of Envirosafe with gauge showing about 40-42 psi. The 240 is now blowing 50 degrees cold air from the vent. I'm going to run it for a week and check the PSI in the evening.

I didn't add any oil to the system.

 

'envirosafe' is a propane/butane blend, much like "gaz" backpack stove fuel.

its not legal for any motorvehicle air conditioning application. just sayin'

 

They sell it on ebay as A/C gas replacement for r12 and it works!

As far as cost, it took 2 cans for my empty 940, i believe they were 6 or 8oz... Still doing OK after a couple of years except in extreme 95+ temp, but it's a black on charcoal car so, acceptable!

 

Did you add any oil?