Hi all, I would like to test my ac system for leaks. Is this something I can do? I have r12 and have no plans on converting but want to make sure system is ok before filling. Is testing it myself possible and how? or do I need to take it somewhere?
I ma not an AC expert, but this is my advise. Take it to someone who is good with air conditioning and ask them to pump it down with a vacuum pump, and have them see how long the system holds vacuum. If it holds vacuum for a long time, the system has no leaks and can be recharged. If it holds no vacuum, you need to start looking for leaks. Make sure you take your car to someone you know and trust because there is big money to be made in misdiagnosing AC systems. Ken
Good call staying with R12. While those systems can work really well with R134a, they were designed for R12 and perform best with it. The trick is keeping that refrigerant inside for the long haul and having the system work reliably. First off, Is the system all original or did you assemble it or work on it while working on the rest of the car? Is it actually empty, except for slight ambient pressure, or is there "some" refrigerant left in the system. How long has the system been non-working? If the system has been checked and repaired or was recently working you can pressurize it with R134a (don't run the compressor), then check everything with soapy water while looking for bubbles. You can also use a refrigerant leak detector if you have access to one. The receiver/dryer should be replaced if you open the system to fix a leak. One very common leak point is the compressor shaft seal. You can replace the old ceramic seal with a modern, double lip neoprene seal to make it more reliable. If the system is original and has been "dead" for a long time, you'll need to do a good bit more to guarantee good results. Leak testing and recharging an old system like that "might" work just fine, but most often the results are poor or don't last. With a long dead system it's best to disassemble and reseal everything, test the POA and TXV, replace the receiver/dryer, flush the components and check for internal corrosion. Hope this helps.
I bought the car a year ago and the system was intact bolted up but not working. I was told there was nothing in the system as well. So i bought a o ring kit and replaced all the o rings in the engine compartment and the couple at the condenser. The system appears to be original in all aspects based on my limited knowledge. Sounds like this is a big project that I should buy all new parts to start with and maybe tackle when I have more time. Dont Have much ac knowledge and appreciate the help.
It sounds like a big project but its nothing that can't be easily done on a weekend. The only thing that might take time is pulling the compressor to change the oil and maybe having the shaft seal replaced at a shop. The evaporator and condenser can be flushed in place. You need access to compressed air for flushing, though. The POA is a tossup. They don't fail very often so yours might be ok. You can send it out to be tested and calibrated for about $20. Good Luck.
I Own and operate a HVAC biz in North Florida. Although automotive A/C and residential units are very different they all work on the same basic principal. When I revived my system in the 68 Riv I knew the compressor shaft seal was leaking due to the oil stains all over the underside of the hood and R fender. I replaced the compressor but kept the clutch, Bering and coil Assembly's to save a Little cash and I already owned the tools to remove and install them. You need to presser test the system with nitrogen not compressed air. pump it up to 100 PSIG let it sit over night. if it holds you have a sealed system. then evacuate to -29.9Hg to remove all air and moisture. I let mine sit over night just to be sure it held vacuum then recharge by weight the rated charge of the system. It really blows cold and has all summer. If you don't have the proper tools and equipment, do what you can at home then take it to a good A/C shop for the rest. Do you have a source for the R-12? your local shop may charge you through the nose for that. I have a bud in Refrigeration that has a full 30 Lb jug of it. I traded for 4 lbs of it.
I have been performing A/C repairs and retrofits to 134A for years. Replace the drier/dessicant (sp?) and the valve cores. This will keep the system reliable. Then pressure test the system with shop air, vacuum does not test sufficiently. If it holds, then vacuum the system for at least 20 minutes in low humidity or 40 minutes in higher humidity. Put about 3oz of R12 oil in the system and charge the recommended amount. This should give you years of enjoyment.
I'm watching this discussion intently as I have a Complete A/C system on my car that's not functioning, but appears to still be sealed up. Based on the experience of those in the group, what are the major areas or components in the system that are likely to fail? Conversely, which are most likely not to need any attention or replacement?
I just got the car last Sunday and haven't had a chance to check yet. It appears all components are in place, and all lines still hooked up, though for some reason the compressor was pulled off it's brackets and set aside laying against the inner fender.
I have not looked but just curious but where can I get a drier and valves and r12 oil at? How do you put air in system? Do they make a fitting I can buy?
You can get all the mechanical stuff you need through most any parts store. The shrader valves (cores)are the same as in your valve stems. You need a charging manifold to connect to the system. should be able to get one from a pawn shop for 25.00 or less. The Refergerant oil is a different story. POE oil for 134A is available anywhere. The oil for R12 can only be purchased through a HVAC supply house as it is only really used anymore for Refergeration compressors. lately I have not seen it sold in smaller than a gallon size. You only need about 8oz.
Briz, If he uses 134a, shouldn't he use esther oil because of it's compatibility with the residual R12 mineral based oil that may be left in the system? Ken
Gary, If you do decide to convert to 134a, George N's Buick Performance website shows hoe to set up your AC system to 134. Ken
Geroge Nedehovich (I hope that is spilled correctly). He has the Buick Performance Club website, which is packed full of good resto and repair info. George is the man! Ken
Just took it for granted that he would read the directions on the retro kit and use the flush and change the orifice if applicable.
If the AC systems on these cars were much newer, I would agree with just changing the dryer and a few seals then recharging. However, the systems mentioned in this discussion are near 40 years old and there's no telling how long they have been out of service or why. I've repaired/rebuilt/converted very likely 40+ GM POA systems from the 60s and early 70s in the past few years (I do it as a secondary job) and can say from experience that those systems often have issues with internal corrosion after being "empty" for an unknown length of time. The same leak that let the refrigerant out will usually draw moist air in. Moisture causes corrosion to the raw aluminum internal surfaces of the parts. I've opened up some long dead systems and they are clean as a whistle. New seals, a receiver/dryer, a good evacuation and refrigerant charge...It's good to go. I've also opened many "totally intact" systems in which corrosion of the internal parts required replacement of nearly every piece of aluminum due to corrosion. I'll say there is a 50/50 chance of a system being "ok" internally , but the actual odds aren't that good. There's no way to look at the outside of an old AC system and gauge the internal condition. A 2-3 hour disassembly, inspection, cleaning and reassembly session can save a ton of disappointment and lead to an AC system that is reliable for many years.
I have converted many r12 systems including my72 to 134A it Blows super cold , You have to use Pag oil when coverting as said earlier dont use ESTER , and flush your system with a good A/C Flush , To get any Crap out of it . except the compressor , It can be drained and systemoil can be put right in the compressor , Just remember to turn compressor about 20 times after you Charge the system to get the oil moved around, also see georges site here is the link http://buickperformance.com/ac.htm
I'd like to add a +1 to what GSX1 said about the system oil. PAG-100 seems to lube better than Polyol Ester. The recommendation for Ester oil in conversions was made early on during the industry wide switch to R134a. There were many "problems" that appeared on paper back in the day, but many of them proved to be a non-issue in actual practice. Oil and hose composition are 2 of the big ones. If the system is thoroughly flushed and the dryer replaced during a conversion, any small amount of residual R12 leaching out of the hoses won't be an issue. Ester is still recommended for conversions today mainly to help standardize things for repair shops: -R12=Mineral oil -OEM R134a= PAG -R12 to R134a conversion=Polyol Ester. Because people don't always follow recommended procedures, those recommendations don't really mean much these days. It was a good idea, but... As long as the system is clearly labeled as containing PAG there should be no confusion if the car finds it's way into a shop at some time down the road. Barrier hose is required for all new systems. In older, converted systems, it was feared that R134a would leach out through the old style hoses due to the molecules being smaller. (ambient leakage) Non barrier hose DOES have some ambient leakage, but the amount is actually about the same with R12 or R134a. Barrier hose should be used when replacing hoses because it retains the refrigerant better. I often equate it to modern oil vs the oil that was available when these cars were built. The old oil did the job well, but newer oils do it better (ZDDP issues aside). You wouldn't use an SD rated oil today just because it was recommended back in 1971.
