With record breaking temps up here in Montana, its about time to get the A/C on my 85 300sd working. I had the compressor replaced during the winter and the MB shop told me that they couldn't put in 134a because they didn't know if it was compatible with the Freeze 12 that was in the system.

They did drain it, but now I need to know two things- can I put 134a on top of freeze 12? And how the heck do I get the right fiting so that the cans of 134a will fit on the correct nozzle?

-Travis

"Freeze 12" is 80% R134a and 20% R142 anyway. You can buy conversion fittings at most auto part stores.

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

I bought one of those conversion fitting systems but it still wouldn't work out, even though it said it works with "all cars". Perhaps I am trying to add the refridgerant to the wrong valve....

When recharging you add the 134a with the car running and A/C on correct? And you add it to the "low side" which should be a valve in between the compressor and the evaporator, correct?

Correct on both counts. Note also that the low-side line is much larger than the high-side line.

And you often need to bring the engine to a fast idle, say>1500rpm.

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

OK so fast idle the engine with max AC on while doing all this. But I still have the valve wont fit problem.

All I do is unscrew that little cap with my hand and attach the hose correct? Or do I have to unscrew the cap and then use a wrench to remove the fitting so that I can get the recharger hose closer to the actual valve? (the problem is the little nipple on the recharge can doesn't reach far enough into the fitting in order to depress the valve and get it pressurized)

Thanks for the help with these relatively simple questions....

there is a collar that lifts to push the hose in just like an air compressor fitting.

also, if you are not putting the entire can of 134a in, always charge with the can upside down. this freon is a mixture of several chemicals, and it will seperate at differant pressures. so you need to put in the liquid, VERY SLOWLY if the system is running.
it is best to weigh the correct charge and put it in on the liquid side *(small line high pressure fitting) after evacuating the system and with the system NOT running.
but minor charging can be done on the low side, just use liquid with the can upside down.
John