Too much oil in my AC?
 

Hi everyone.....

Quick question... My '90 300SE has been retrofitted to R134a by a dealership before I bought the car. Last night, I hooked up a pressure gauge to the low side, and after adding a touch of refrigerant, I removed the gauge. The Schrader valve malfunctioned, and started venting my charge quite rapidly.

Afterwards, there was oil everywhere. Nasty smelling stuff.

Anyway, how much oil would you normally expect to come out of the low side in such a situation? I feel like there was waaaay too much oil and that perhaps my system is over-oiled.

I've already replaced the valve and re-charged the system. Works about as poorly as it used to, which is to say that cooling is marginal at best, and non-existent at idle.

Any hunches?

Thanks!

It just depends on where the oil is in the system at the moment. Just because there was a gush there does not mean that it had too much oil. You may have lost a good portion of it, or it could indeed have been too much.

Unfortunately there is only ONE way to know that you have the right amount of oil in the system. That is to do a complete flush of the system, change the r/d, put in the correct amount, evacuate and recharge.

Oil in a modern a/c system is a guessing game all the way. If you're dealing with a car for which you know the history, then you are much better prepared to know when and how much to add.

There is potentially some good news here though. If you were to flush, add the correct amount of oil, replace the r/d and THEN charge by WEIGHT, you could get a proper charge in the system and run a better chance of improving a/c performance.

Find the correct amount of R12 that the system requires and multiply that number of ounces by .7. Using a charging scale charge the system with 70% and test it. If you add any at all, don't add more than one ounce at a time.

Oh yeah, the work I described here, sans the 70% rule, is exactly the same job as reverse converting to R12. If you want proper a/c performance in a system designed for R12, then USE R12.

My $0.02,
Larry

Thanks Larry.


Yeah, I would love to go back to R12, but to find somebody willing to do it..........

To have a decent a/c system on that car you need several things to happen.

#1) Making sure that the fresh air door closes all of the way!

#2) Making sure that the system isn't overcharged. (1.9-2.2 lbs on that car)

#3) Making sure that the condensor & radiator are CLEAN!

#4) Having the condensor fan run (high speed) as soon as the temp & pressure builds.