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A/C Compressor - front seal failure


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I am on my third compressor - 1970 396 Chevelle. The front seal after a few weeks fails and sprays oil out the front. Everything is new in the system, the last compressor was also brand new not rebuilt.<P>Looking for help on what may be the cause.<P>The POA valve was not new when I resotored the system as it was replaced by the previous owner - was fairly new.<P>Thks <P>Rich

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TAKE THE COMPRESSOR APART!!!!! and report back what u find. There may be rust or chips or something causing the seal to go bad. Depending on what u find may depend on what else needs to be done. IS it r12 or 134 or what???? we need more info.

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look well the belt pressure about your compressor if it's too hard, it's pull the rotor enough to leave out gaz and lubricant, that cause domage on bearing compressor and result your problems.

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Too much belt tension is unlikely to cause this type of failure because the compressor pulley rides on a double row ball bearing that is mounted on an extention on the front of the housing.the compressor shaft passes thru this extension/bearing/pulley and carries no radial load at all.Sort of like the floating axles on large truck differentials.Look for too high internal pressures caused by either a blockage of some kind or too much freon.

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Thks for all your replies,<P>Just to answer a few questions, the belt tension seems ok, the freon is R12 and the suppliers were different. The first two were rebuilds, this last one is brand new. Each time the system was filled it was filled by a reputubale A/C mechanic.<P>One other question for Carlnut50 - if a blockage, in your opinion where would it most likely be - here are some more particulars of what is new in the system,<P>NOS Evaporator, the dryer was rebuilt, the condensor was checked flushed and cleaned by a reputable service, the A/C hoses were refitted with new hoses, all o rings are new, the ambient temp switch is new, the only thing I did not change was the POA valve , which is farily new and the thermostatic expansion valve, would either of those two items cause a high pressure issue? <P>Also I had one other suggestion from someone - he advised that if the sytem was not vacumed out completely that a small amount of air if left in can mix with the R12 and create an acid that would attack the seal - does this sound possible?<P>Thks<P>Rich<p>[ 08-26-2002: Message edited by: richr ]

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disassemble the compressor and take a look. If moisture is in the system there may indications of rust. The seal failed on my compressor. The area on the shaft where the seal rides had a slight amoutn of rust altho it WAS high mileage.

Get a pressure gauge and check your own pressure. cheap ones r available.

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  • 4 weeks later...

Hi Rich,

This is not as rare a failure as some may believe.

There are three different seal designs. The first design has been unavailable for many years. It was replaced in the late 70's with a ceramic seal. This is the seal of choice (in my opinion).

The third design, is nothing more than a design cheaping exercise. They can be installed backwards - and cause a loss of refrigerant and oil.

I would recommend you find the ceramic design. Make sure it is absolutely, surgically clean when you install it.

Also, there is a special tool that is installed on the compressor shaft. It prevents the keyway from damaging the inner diameter of the seal.

Hope this helps.

If you need to find me - try bowtieollie@chevytalk.com grin.gif

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