Many people ask what maintenance steps they should take for their classic’s factory a/c system. Our tech guys always give the same, straightforward advice: “USE your air conditioning!” Contrary to popular belief, refrigerant is not consumed by using the air conditioning. I know, you have been lied to your whole life.
A very common source of lost refrigerant or oil in a functioning, leak-free system is at the compressor shaft seal. This is typically the result of cars and trucks that aren’t driven on a daily basis and/or experience sporadic use. Shaft seal leaks have been known to develop with periods of inactivity as short as two weeks. The common result is partial refrigerant loss and/or shaft seal oil leaks.
SANDEN COMPRESSOR
It’s fairly common for someone to install a rebuilt or even new factory-style compressor, (A5, A6, R4, RV2, York, Tecumseh, etc.) only to find that the compressor shaft seal is leaking refrigerant or oil. A little-known fact about A/C compressors is that the shaft seal is kept lubricated the entire time the compressor is engaged and running. Believe it or not, this is true.
Many factory a/c systems lose their charge when the a/c system is not being used. This happens as an under-lubricated seal around the compressor’s crankshaft dries up and develops a leak that allows for refrigerant and/or oil to escape. Not so much of a problem years ago when you could bring your car to any service station and get R12 topped off for 99 cents; but those days are gone like the old Freon.
UNDERCHARGED SYSTEMS
Below are some symptoms often seen in systems that are slightly undercharged. These conditions can indicate a loss of refrigerant as a result of your car’s air conditioning sitting dormant. (Please note: this is not an exhaustive list and your classic car may exhibit some or all of the symptoms below.)
• Clutch quickly cycles on/off (Not related to Suction valve system such as General Motors POA, HGV or STV systems, Ford POA systems or Mopar EPR systems.)
• Slightly low suction & discharge (low & high) pressure.
• Cool, not cold air at the vents. (Result of cold, but not frigid evaporator temp.)
• If you are using R12 refrigerant in your ac compressor, bubbles in the sight-glass ** TIP – the sight-glass will never be clear on a 134a system.
• Oil splashing the underside of the hood after slinging from the area of the clutch. While this symptom can also indicate other problems, (contaminants in the system, bad shaft seal, high head pressures). It can be the result of oil leaking from the shaft seal as it dries up from not being used and gathering around the clutch & pulley until being used.
SANDEN TOP PORTS
Air conditioning systems that are drastically undercharged may likewise exhibit some of the symptoms below:
• Compressor clutch doesn’t engage (If system equipped with a low-pressure switch.)
• There is very low suction pressure. (System not in a vacuum.)
• Very low discharge pressure.
• Warm air at the vents.
• If you are using R12 refrigerant in your ac compressor, bubbles in the sight-glass ** TIP – the sight-glass will never be clear on a 134a system.
• Oil splashing the underside of the hood after slinging from the area of the clutch. While this symptom can also indicate other problems, (contaminants in the system, bad shaft seal, high head pressures) it can be the result of oil leaking from the shaft seal. This happens as it dries up from not being used and gathering around the clutch & pulley until being used.
For more information on the compressors and clutches check out this blog here.
Now, if your car is not used often and/or is stored for much of its life, simply start the car and run your air conditioning (with the compressor engaged) for approximately 30 seconds. Doing this every couple of weeks or so keeps the compressor shaft-seal lubricated, which can prevent most shaft seal failures. In most cases, the shaft seal will re-seal itself once you start using the air conditioning again, though your system might require “topping off” of refrigerant and/or a good wiping down of the under-hood compartment until any oil clears the pulley assembly.
To view, all Classic Auto Air Sanden compressors follow the link here.
I have a problem with a 13 year old Vintage Air system (R-134a) that will only blow 45-50 degree air. Pressures look OK and the system won’t take any more than 1/2 can of refrigerant every Spring. Would like to see trouble-shooting tips on this type problem. It just now occurred to me to check the heater valve to make sure it’s completely closed.
Thank you for this information. I took my 93 vette in to a station, and he said the compressor shaft was leaking, and I needed a new compressor. I am going to charge it, and use it to see if it seals up again.
Good article! I overhauled the A/C and let the car sit in a hot garage at 100 degree summer temp without ever driving it for a year. All my repairs were for nothing, the valves and compressor are now leaking.
I have a 1971 C20 with factory air, I just acquired it a few years ago so I am not sure of what has been serviced in the past. I don’t really use the air much being in Michigan and there are few days in which the windows won’t do.
I just changed out the water pump, thermostat, and hoses this week and today when I pulled into the garage I had something leaking, I could hear the audible drips. At first I thought that it was an improperly installed hose but on inspection it was dripping from behind the passenger side wheel well, and I trace it up to the ‘black box’ which is the AC. It is dripping heavily onto the well and it is also dripping inside onto the passenger side floor mat. It is a reddish liquid but does not smell like antifreeze. I wasn’t using the AC, but was driving it pretty hard to test the new pump. What happened? any help would be greatly appreciated.
air-condition oil is leaking underneath my Chrysler 300 c 2005/2006 hemi 5.7L and falls on the cross-bar. I cannot find where the oil is leaking.
Hello Franklin
I have a factory air division in Florida that would actually be able to help you out with that. Here at the Texas location a only handle
complete new aftermarket systems. Here is their number if you would like to give them a call 877-371-0570. Thanks again.