Hobo_wes

I am replacing my expansion valve and dryer this weekend. In the instructions in the Hayes manual, it says to put in 1 ounce of system oil... but doesn't say what type. I go to the local Advance Auto and they have 4 types of A/C system oil... 1 for r12 systems, and a light, medium, heavy for R134a systems... Which of these oils do I need to add to the dryer? (I know its not the r12, it is a 134a system...) Also, is the 1 ounce correct? Do I just pour/squirt/inject it in one of the openings on the dryer? Oh yeah... '95 SL2

Thanks!

nutjob

You could pour it into the evaporator instead of the filter/drier. Unless someone here knows try ackits.com for advice on which R134a oil to use. The 1 oz. would be correct as it makes up for any loss from replacing the drier. Oil freely circulates throughout the a/c system as its pushed along by refrigerant to ultimately end up in the compressor for lubrication so each component retains some oil from circulation. When replacing any component a certain make-up oil is replaced along with it to keep the system at proper levels. Hope you have a/c back soon.

Ssicarman

Was not aware that there were different viscosities availible. The service manual only says that it wants PAG oil (Polyalkylene Glycol Synthetic Refrigerant Oil).
The reciever drier is supposed to get the one once of oil when it is replaced. You also need to take note of how much oil you get out of the sytem when you pull the charge out. Install the same amount of oil that came out.
If the equipment that you are using to recharge the system has no way of adding the oil then yes install it into the hoses or the drier.

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Hobo_wes

I had the system tested at a local quicky oil change place this weekend (about the only thing I will let them do to my car) and everything worked, but no cold air... They suggested that they expansion valve maybe stuck open/closed. I asked a couple of machanic buddys too and they said that would be the place to start... I had the oil change place empty the system after they tested it so I don't know how much oil was in it... But they did say that if they pulled vacumn and recharged the system they would put the oil back in it... So I just have to replace the parts... I do have another car to drive that has A/C, but it burns premium and gets a lot less mpg than the Saturn, so it's not "critical" that the SL gets on the road asap... But it would help the wallet out...

Thanks for your help!!!

nutjob

Its a brief on what you'll need to know attempting to work on your a/c system. Its not likely that the expansion valve is the fault but most likely a leak has occurrd and the a/c won't run, correct? Reading the article in the link will give you the basic information before going on hunches by someone other than an a/c repair shop. Guessing is for amateurs and a telltale indication of their abilities w/o carefully troubleshooting. A/C work entails much more than suggestions when you can start by visually inspecting the entire system with hints from the above link. If you find the source of the leak you can decide whether you can handle the entire repair or just replacing certain components and leaving the rest to an a/c shop equipped to finish the job.

Hobo_wes

No leaks… The reason I took it in to have it checked was the compressor would not engage at all. I checked everything I could find to check, electrical/mechanical, etc… The system was a little low, but within the “normal” operating range. It was completely evacuated of 134a (the system oil was clean when it came out too) and vacuum was pulled on it 3 times over a 2 ½ hour period. In a 15-25 minute waiting period between the vacuum pulls, no leakage was found. When the system was recharged the compressor came on and everything worked as expected, except there was no cold air from the vents… The system was even checked with a leak detection gun of some type. After discussions with other service tech’s and the manager, the A/C tech went to their manuals, the internet, and even called a “friend” (I found out later it was a tech at the local Saturn dealership) and all seemed to agree that the problem pointed to a blockage/closed or open valve, most likely in the Expansion Valve/Orifice Tube. The car was not driven much by the original owner in the last 12-18 months, and I doubt the A/C was used at all. I was told, it wasn’t working when it was put on limited duty… I am really looking for the most conspicuous items that could cause the problem… I am trying to starting with the “least” expensive options. After the check, I feel pretty sure it is not the compressor but some blockage/valve in the system… I am not new to cars, by any means, but haven’t ventured into A/C systems… As I see it, there are 4 major components in an A/C system… The compressor, the expansion valve, the dryer and the evaporator… With the compressor working, the dryer, and expansion valve replaced, that only leaves the evaporator… and that is expensive, so it goes last…

Sorry for the long note...

Artificialist

My dad's Lexus ES300 had an expansion valve failure. It cause intermittent cooling of the car, even when refrigerant levels were normal.

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nutjob

Whenever the compressor doesn't engage 99% of the fault is due to a leak, period. The low pressure switch detected the lack of refrigerant during the last run and automatically opened the clutch circuit preventing any further running of the a/c system protecting the compressor from lack of lubrication. This kept the a/c from operating as you found out without knowing the reason why the compressor wouldn't engage the first time you tried to use it. You had a leak whether you want to believe it or not. When the system was recharged back to normal the low pressure switch automatically resets allowing clutch/compressor operation. Yours was a leak and may be from lack of use as the usual place for normal acceptable leakage is through the compressor shaft seal. As good as your system is with the excellent results from the vacuum leak test this doesn't rule out pressure leaks, only vacuum leaks. Pressure tests involve the leak tester moving over the entire system to detect the slightest pressure leak. Its accepted in the industry that automobile a/c systems will lose some refrigerant, the minimum loss is measured in grams/yr or 0.5 ounces (14g)/yr, well below what's considered a leak. A/C systems are sealed and pressurized at all times. When not used the system pressure is still averaging 75-90 psi. When its running, one side, the high side, will be around 175-250 psi+ depending on outside temperatures. The highest pressures are reached on hot humid days. Unless you can state the pressures, both low and high side at 2,000 rpm, "normal" lacks the technical description of what the pressures are when measured. To continue, evacuation, leak testing then recharging and having the compressor run was good in that many areas were covered but there remains some questions. I'm curious as to how it was determined that the expansion valve is faulty.

Hobo_wes

Thanks guys! I think the pressures were like 25-28 and 220ish... at idle at around 102 outside temp. He checked it at different rpm's too... I watched, the pressures did rise and fall with the rpm's... I will try to check my paperwork from them to see if they put the pressures down... Also, where is the "blend door" in a variable displacement compressor like ours? Nutjob, the link you posted apprears to have been removed... Can list the site name or something...

Thanks!

nutjob

A/C Basics title. 25 psi low and 220 psi high @ idle is an invalid pressure reading. Anyone that knows a/c concepts and works on automobile a/c systems will set the engine rpms at the recommended factory rpm from 1500-2000 and not at idle. If I were to interpolate from your observations of the low pressure reading of 25 psi @idle, then at 2000 rpm the low pressure reading will be reading a vacuum or negative pressure. Any pressure below 25 psi@2000 rpm indicates a loss of refrigerant. Of course I don't expect you to post all the readings taken at various rpms to allow anyone to analyze your situation so it remains a mystery of what's wrong with your a/c.

The blend door is just a panel that moves to re-direct the airflow allowing heated and cooled air to blend in varying amounts to customize the comfort level. The heater is always on so chilled air is mixed with the hot air for the climate control system to automatically adjust to the desired temperature. This blend door is either actuator motor controlled or a lever that moves from cold to hot.