Should I add oil to R134a?

You also are going to replace the dryer and expansion device aren't you?

You need to take back the cans with the oil already added and get regular ol' 134a in a can. Make sure the compressor manufacturer did not already put oil in the comrpessor as well.

Find out how much oil your system takes and add the oil back before you seal the system up. I do like to spread it across the system like the book says to avoid slugging the compressor with oil.

Having the proper oil level in the system is critical to compressor life and system performance. Make sure you have exactly the right amount!

Steve B.

As you suggested I returned the cans and bought regular R134a cans.

Yes I did replace the dryer, but I could not find the expansion device. This is a 1990 Geo Metro. It does not use an orifice, and I can't find anything else on the low pressure line. I am guessing that the expansion valve must be inside the evaporator. The only way to get at it would be to remove the evaporator, which I am not ready to do. I measured the exact amount of ester oil, and poured some into the compressor and some into the condensor. I sealed it up and ran a vacuum pump for 2 hours. The vacuum stayed at 30"Hg for more than six hours after the pump was turned off. I am about to recharge the system today. I will let you know the outcome.

Steve B. wrote:

You are a fool if you don't even check the orifice tube/expansion valve before charging the system.

So Bruce, how do YOU check the expansion valve when you charge a system like this? Better yet, how do YOU check the orifice tube on a receiver dryer system?

Toyota MDT in MO

I don't know this system and apparently he doesn't either. He assumed it had one and he wasn't going to check it.

In response to your question, I would pull the orifice tube and check to make sure it has no debris in it at the very least but I'd jsut replace orifice tube. It's chump change in comparison to having redo everything again.

-Bruce

I don't know your car in particular but on many GM cars the orifice tube is in the high pressure line. You unscrew the line and slide the old one out then slide a new one in.

Rebuilt compressors have a long history of less than stellar results and if you don't replace the orifice tube / expansion device you instantly void the warranty on the new compressor. It is worth taking the time to find it and replace it.

Good luck! Steve B.

Your response was rather abrasive considering this fact.

That is a good plan if this car had an orifice tube. It has an expansion valve, however, which is next to the evaporator. There was no direct mention of system contamination. I see no reason to spend hours of time replacing or "checking" a part that doesn't need any attention. He said he flushed the system -- if done properly, even an expansion valve can be remotely cleaned by backflushing.

Toyota MDT in MO

Thanx for pointing out that his car has an expansion valve.

The OP is replacing the compressor so there is at least a good chance that there is trash in the system. I would replace the valve if I was doing the job myself if only to preserve the warranty on the replacement compressor. I also don't understand how you can do a decent flush of the evap and lines with the expansion valve still in place. How do you manage to get enougt fluid to back feed through the expansion valve to flush it all out?

Steve B.

Sure, I could have candy coated my response but the fact remains that A/C work is finicky and if you will neglect things because "I'm not ready to do" then you're gambling. For me, at least, gambling with A/C work is not worth it. It's a lot more time and money than it's worth if it doesn't work out.

What's involved in checking the expansion valve? You said it was next to the evap. Does it mean the evap core has to be removed to get to it?

-Bruce

...and dangerous...

...risk of injury, risk of property damage, risk of death...

If you have to ask...!

You can't be successful flushing 100% of the time, but experience will tell you if the cleaning process was or was not a success before recharging the system. Every system poses it's own challenges related to which lines and components need to be removed to facilitate flushing. Expansion valves can be cleaned in place if the evaporator has large enough tubing, or for several hours of extra labor in the case of most smallish import cars, it can be removed and cleaned or replaced if too crapped-up. An example of simplicity would be Chrysler H blocks -- really easy to get to!

Toyota MDT in MO

I am the OP. I spent many hours looking for the expansion valve. I could not find it in the engine compartment. I assumed it had to be inside the evaporator on the passenger side. Taking that apart is not an easy job, so I sealed it up and hoped that the flushing would have taken care of any blockage in the expansion vavle.