A/C conversion 91 560 sel

Do a Google on sealants. I have seen them for R-134 so I wouldn't be surprised if they have one for R-12. Really be sure you find all the leaks before conversion. Use a dye and black light, looking everywhere. You'll need a freon sniffer for the evaporator. But it could also be an expansion valve connection leak since it's up there too. The mechanic can get close to the Ex valve to see if it's the cause. Compressor seals and suction hose are two other places to focus. If you do have an evaporator leak and can't find a sealant, ship the car to Maine and sell it. I think you'll find replacing that item incredibly expensive--mostly labor.

As for the R-134 refrigerant, it works fine in my '86 420SEL in sticky hot Georgia. However you need to be sure that you replace not only the dryer but also the two pressure switches that engage the compressor clutch. I think many people who are not happy with R-134 cooling forgot to have them changed and the AC is not operating withing the design characteristics of R-134

In any case it would be good to find the leak. To the horror of many 'experts' I have converted a Pontiac and Volvo using the cheap kits from Kmart. No replacement of dryers, switches or even oil was done. Worked wonderful for the 3 years in both cars until the Pontiac was traded in and the Volvo was laid to rest.

I found the sealant. If you do have an evaporator leak and can't find

:-) My thoughts exactly! If it is the evaporator and it is too large to seal, I am screwed. I am not going to pull the dash.

Great, my kind of weather! :-)

However you need to be sure that you replace not only the dryer but

Good advise. I found another mechanic that changed his own 85 500SEL to R-134 and he says his works fine. And he is going to do it for 150.00. The system had gone empty. He placed the ester oil in it, changed the fittings, and put the vacuum on it over night. Today we are to find the leak and fix it. Then recharge with R-134. Fingers crossed.

Thanks, Ken

Thanks, We hope to find the leak today.

Ken

Ken, That's very high! Go to a place that can inject fluorescein into your system after it is drained. It will reveal any leak when exposed to UV light. You will nedd a new receiver/drier-standard procedure when converting. R134 is dirt cheap and the required change of cap colors included won't cost anywhere near $600! P.

Am in Dallas - have converted my 85 380. 500sel, and 90 560sel - to 34. My mechanic has done the job for 250 each. Still good cold air....does the $600 include S.T.D. protection?

I have done a 1986 420SEL and stayin' cool in GA. Be sure you have a good mechanic do the job and ask to see the old pressure switches along with the usual parts. Also I suggest you have a dye test done and fix any leaks (compressor seals or low side suction hose).