Help! my AC is acting up

Paula Ds SC

Registered User
:confused: I have a 1990 sc that had a great ac until July, was told by a mechanic that the seals in the compressor have broken off and have clogged the system and the only way to fix it is replace the whole thing.Can anyone help? Please help i live in SC and it gets really hot here.
 
Can you turn the center of the compressor by hand or by the small bolt in the center? If not, then the mechanic is telling you the truth. The compressor has siezed up and the inner seals have broken off. This is what they refer to as black death failure and to fix (and it stay fixed), you have to replace just about everything under the hood. They call it fire-wall forward.
In my experience, you can probably reuse the high pressure/manifold/suction line assembly if you flush it. But the compressor, condenser*, liquid line, and accumulator will need to be replaced.

* - This part could possibly be reused, but its not advisable. The only way to know about the condenser is to completely dissassemble the compressor and account for all 10 of the teflon piston seals to ensure that they didn't get pushed into it. It they did, then the condenser will be partially blocked and you'll have poor cooling. Due to the way its designed, it can't be reliably flushed, so they will just replace it. :cool:
 
:confused: Thanks for that info,but to honest with you and to feel really really Dumb i couldn't find the stupid thing.There is a lot of extras on SCs and i stood there calling out what i could see. The air is cold, its just not cold enough to keep you comfortable in the heat of the day.Night is fine cooler days like today when its only in the mid 80s its fine too.Guess i will be buying a new system but she is worth it. Thanks
 
The fact that it cools is good news. It means that the compressor is probably OK, but maybe low on refrigerant. Low on refrigerant means that there is a leak somewhere in the system (usually at one of the line couplings where an Oring is). A shop can simply top it off and leave the leak unfixed, but that eventually will make the compressor croak. A shop can find the leak with a sniffer device. When they fix it, they should do 2 things while they're at it.. replace all the Orings, add back more oil. I'd advise you not to run the A/C until another shop takes a look at it.

When refrigerant escapes, it takes lubricant (oil) with it. If enough of it gets out, the compressor will run dry and that will eventually kill it.

The compressor is driven by the large main belt and is at the top left when you're facing the engine from the front. It is silver in color and has a black pulley about 6-8" in diameter.
 
:confused: The machanic told me that the system tested full in refrigerant. He is a good mechanic and i have used him before on the Thunderbird and on the taurus but, do you think i should have it checked out by another mechanic? Thanks
 
Its unusual for a compressor to fail and the system to be full of refrigerant... in fact, I've never heard of it happening.. 95% of what I've heard about (I'm not a mechanic, just learned a whole lot from other sources on the subject and from experience with the SC) A/C compressors failing is due to leaks or improper repair. I've just never heard of one wearing itself down.

If indeed the system is full, and only problem is a weak compressor, then thats what I would have replaced.. You shouldn't need a new condenser or high pressure line, or liquid line although a new accumulator would be a good idea along with new O rings. I'd be curious about the static and running pressures. My fully charged r134a pressure is around 75psi and running pressures are around 290/28 on a 91 degree day.

As for what happens to a compressor, there are 5 double ended pistons, arranged in a circle, which slide back and forth through 5 double ended cylinders. There are teflon rings/bands which seal the pistons to the cylinders much like a engine piston. When one of those bands wears out or breaks, then the compressor weakens; it stilll has 9 working cylinders. The pieces of the band can go a couple of places, but most of the time, they end up jammed in the end of the cylinder that they belong to. It that happens, then that debris is contained in the compressor and the condenser is spared. However, if left untended, the cylinder will start to rub metal-to-metal and grind aluminum bits mixed with a bit or residual hot oil out and coat stuff and clog the Orifice tube.

This is why, for most Ford cars and some GMs, shops replace most of the A/C under the hood. Its quicker to fix and for them, there is less risk that something else which was weakened or broken will break later and the customer comes back mad. The only way to really know is to dissassemble the compressor and account for the pieces.. I don't know any shop anywhere which is willing to do that as time is money.

So, what I would do if I were you is: 1. Don't run the A/C 2. Have a 2nd test done and readings given to you 3. If they say that the compressor is weak, have the compressor, liquid line, and accumulator (aka drier) replaced; have the remaining lines and condenser flushed and reused. They will tell you that "you should replace the condenser", but with an unsiezed weak compressor, a flush should work just fine.

Good luck with this. :)
 
Oh, BTW, the condenser is the radiator looking thing mounted in front of the radiator. The accumulator is the black or silver canister thing on the passengerside just in front of the firewall. The liquid line is the lowest line from the 2 lines on teh condenser, and it runs into a fitting on the firewall (Thats a thing called the evaporator).

Here's a related thread with picutres of these parts. :)
 
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