ac quit strangely

Hi,

Long time lurker, think this is my first post.

94 Buick Roadmaster Wagon 350 ci, all power, etc.:

Yesterday, about 8 highway miles away from home, stopped at a
stop light. As the light turned green and we turned left, I
heard a noise like a little 4 cylinder engine revving up as it
left the light. Glancing as we turned, I thought it was a
strange noise for a Ford pickup to make.
Around the corner and the noise continued, now noticeably
following our own engine speed. At the same time I groaned
loudly because I smelled what I thought sure was antifreeze.
We were going to Lowes. The noise subsided slightly as we
crossed the parking lot and the smell of antifreeze also
subsided. Parked, the noise wouldn't come back but the
antifreeze smell was unmistakably present.
Nothing wet under the heater core when I looked; that was
good. Popped the hood, all was dry and there was only the
slightest odor of antifreeze by now. I keep it pretty clean;
everything looked fine under the hood. Belts OK, levels OK,
etc.. No dash warning lights. Serpentine OK, ac compressor
spinning OK. Coolant appears slightly low but haven't checked it
in quite awhile.

Loaded the wood, started out, and the previous noise AND
antifreeze smell was gone. As I recall, antifreeze smell lingers
afterwards, right?
So was the air conditioning I quickly realized! It blew only
hot air; not the faintest hint of cooling; in fact, it was hotter
than the Vented air by a few degrees. OUtside temp was about 94.
So, I would surmise that both the noise AND what I thought was
the odor of antifreeze were connected.

Anyone have a guess what happened?
Was the smell actually the ac compressor filler?
What would have made the engine-speed related sort of "tappet"
noise?
Why is the noise gone now?
An educated prognosis?

Thanks in advance for any relevant comments; can't afford to fix
it right now, so was wondering if this was a diy or go directly
to the shop, skip payday scenario.

Pop`
--
If today's the first day of
the rest of my life;
what was yesterday?

Pop wrote:
> Hi,
>
> Long time lurker, think this is my first post.
>
> 94 Buick Roadmaster Wagon 350 ci, all power, etc.:
>
> Yesterday, about 8 highway miles away from home, stopped at a
> stop light. As the light turned green and we turned left, I
> heard a noise like a little 4 cylinder engine revving up as it
> left the light. Glancing as we turned, I thought it was a
> strange noise for a Ford pickup to make.
> Around the corner and the noise continued, now noticeably
> following our own engine speed. At the same time I groaned
> loudly because I smelled what I thought sure was antifreeze.
> We were going to Lowes. The noise subsided slightly as we
> crossed the parking lot and the smell of antifreeze also
> subsided. Parked, the noise wouldn't come back but the
> antifreeze smell was unmistakably present.
> Nothing wet under the heater core when I looked; that was
> good. Popped the hood, all was dry and there was only the
> slightest odor of antifreeze by now. I keep it pretty clean;
> everything looked fine under the hood. Belts OK, levels OK,
> etc.. No dash warning lights. Serpentine OK, ac compressor
> spinning OK. Coolant appears slightly low but haven't checked it
> in quite awhile.
>
> Loaded the wood, started out, and the previous noise AND
> antifreeze smell was gone. As I recall, antifreeze smell lingers
> afterwards, right?
> So was the air conditioning I quickly realized! It blew only
> hot air; not the faintest hint of cooling; in fact, it was hotter
> than the Vented air by a few degrees. OUtside temp was about 94.
> So, I would surmise that both the noise AND what I thought was
> the odor of antifreeze were connected.
>
> Anyone have a guess what happened?
> Was the smell actually the ac compressor filler?
> What would have made the engine-speed related sort of "tappet"
> noise?
> Why is the noise gone now?
> An educated prognosis?
>
> Thanks in advance for any relevant comments; can't afford to fix
> it right now, so was wondering if this was a diy or go directly
> to the shop, skip payday scenario.
>
> Pop`
> --
I think you developed a real quick leak of all the AC coolant. What
you smelled was that and some of the oil in the system as it was
quickly dispersed to the atmosphere. The compressor tried to keep up
and the clutch cycled back and forth real quickly until the pressure
was so low the whole system shut down. Check the pressure in your AC
and I bet it will be ZERO.

"Pop" > wrote in message
news:MV8vg.9$1g.1@trndny03...
> Hi,
>
> Long time lurker, think this is my first post.
>
> 94 Buick Roadmaster Wagon 350 ci, all power, etc.:
>
> Yesterday, about 8 highway miles away from home, stopped at a stop light.
> As the light turned green and we turned left, I heard a noise like a
> little 4 cylinder engine revving up as it left the light. Glancing as we
> turned, I thought it was a strange noise for a Ford pickup to make.
> Around the corner and the noise continued, now noticeably following our
> own engine speed. At the same time I groaned loudly because I smelled
> what I thought sure was antifreeze.
> We were going to Lowes. The noise subsided slightly as we crossed the
> parking lot and the smell of antifreeze also subsided. Parked, the noise
> wouldn't come back but the antifreeze smell was unmistakably present.
> Nothing wet under the heater core when I looked; that was good. Popped
> the hood, all was dry and there was only the slightest odor of antifreeze
> by now. I keep it pretty clean; everything looked fine under the hood.
> Belts OK, levels OK, etc.. No dash warning lights. Serpentine OK, ac
> compressor spinning OK. Coolant appears slightly low but haven't checked
> it in quite awhile.
>
> Loaded the wood, started out, and the previous noise AND antifreeze
> smell was gone. As I recall, antifreeze smell lingers afterwards, right?
> So was the air conditioning I quickly realized! It blew only hot air;
> not the faintest hint of cooling; in fact, it was hotter than the Vented
> air by a few degrees. OUtside temp was about 94.
> So, I would surmise that both the noise AND what I thought was the odor
> of antifreeze were connected.
>
> Anyone have a guess what happened?
> Was the smell actually the ac compressor filler?
> What would have made the engine-speed related sort of "tappet" noise?
> Why is the noise gone now?
> An educated prognosis?
>
> Thanks in advance for any relevant comments; can't afford to fix it right
> now, so was wondering if this was a diy or go directly to the shop, skip
> payday scenario.
>
> Pop`
> --
> If today's the first day of
> the rest of my life;
> what was yesterday?
>

On the back of your A/C compressor is a pressure relief pop-off valve. It
is there to relieve the system pressure if it exceeds about 500 psi. The
noise you described is pretty much what that pop-off valve sounds like when
it releases the Freon from your system. The smell of refrigerant oil being
dispersed with the refrigerant is somewhat like the smell of antifreeze
also. There are several reasons the pressure could reach that high ,and none
of them are very good for your pocket book. The cheapest to fix would be a
radiator fan clutch failure that allowed the condenser temperature to go way
up and increase the high side pressure beyond the relief valve setting.
Another reason would be a sudden restriction in the refrigerant system such
as what happens when the desiccant bag ruptures and causes the orifice tube
or expansion valve to become completely clogged. Of course, a failed pop
off valve might release even though the pressure never got too high.
Because you say the noise was related to engine speed it is also possible
that you had a catastrophic compressor failure. The noise is gone now
probably because there is not enough Freon left in the system to let the
compressor clutch engage. Any way, from the sounds of your symptoms I would
highly recommend letting an experienced technician diagnose the problem.
Naturally, because I was not there to hear the actual noise, It could be
something else, but this is my best guess based on what you said.

--
Kevin Mouton
Automotive Technology Instructor
"If women don't find you handsome, they should at least find you handy"
Red Green

No snipping 'cause this is a good info-post. Bottom posted.

"Kevin" > wrote in message
newsCcvg.66710$9c6.31042@dukeread11...
>
> "Pop" > wrote in message
> news:MV8vg.9$1g.1@trndny03...
>> Hi,
>>
>> Long time lurker, think this is my first post.
>>
>> 94 Buick Roadmaster Wagon 350 ci, all power, etc.:
>>
>> Yesterday, about 8 highway miles away from home, stopped at a
>> stop light. As the light turned green and we turned left, I
>> heard a noise like a little 4 cylinder engine revving up as it
>> left the light. Glancing as we turned, I thought it was a
>> strange noise for a Ford pickup to make.
>> Around the corner and the noise continued, now noticeably
>> following our own engine speed. At the same time I groaned
>> loudly because I smelled what I thought sure was antifreeze.
>> We were going to Lowes. The noise subsided slightly as we
>> crossed the parking lot and the smell of antifreeze also
>> subsided. Parked, the noise wouldn't come back but the
>> antifreeze smell was unmistakably present.
>> Nothing wet under the heater core when I looked; that was
>> good. Popped the hood, all was dry and there was only the
>> slightest odor of antifreeze by now. I keep it pretty clean;
>> everything looked fine under the hood. Belts OK, levels OK,
>> etc.. No dash warning lights. Serpentine OK, ac compressor
>> spinning OK. Coolant appears slightly low but haven't checked
>> it in quite awhile.
>>
>> Loaded the wood, started out, and the previous noise AND
>> antifreeze smell was gone. As I recall, antifreeze smell
>> lingers afterwards, right?
>> So was the air conditioning I quickly realized! It blew
>> only hot air; not the faintest hint of cooling; in fact, it
>> was hotter than the Vented air by a few degrees. OUtside temp
>> was about 94.
>> So, I would surmise that both the noise AND what I thought
>> was the odor of antifreeze were connected.
>>
>> Anyone have a guess what happened?
>> Was the smell actually the ac compressor filler?
>> What would have made the engine-speed related sort of "tappet"
>> noise?
>> Why is the noise gone now?
>> An educated prognosis?
>>
>> Thanks in advance for any relevant comments; can't afford to
>> fix it right now, so was wondering if this was a diy or go
>> directly to the shop, skip payday scenario.
>>
>> Pop`
>> --
>> If today's the first day of
>> the rest of my life;
>> what was yesterday?
>>
>
> On the back of your A/C compressor is a pressure relief pop-off
> valve. It is there to relieve the system pressure if it
> exceeds about 500 psi. The noise you described is pretty much
> what that pop-off valve sounds like when it releases the Freon
> from your system. The smell of refrigerant oil being dispersed
> with the refrigerant is somewhat like the smell of antifreeze
> also. There are several reasons the pressure could reach that
> high ,and none of them are very good for your pocket book. The
> cheapest to fix would be a radiator fan clutch failure that
> allowed the condenser temperature to go way up and increase the
> high side pressure beyond the relief valve setting. Another
> reason would be a sudden restriction in the refrigerant system
> such as what happens when the desiccant bag ruptures and causes
> the orifice tube or expansion valve to become completely
> clogged. Of course, a failed pop off valve might release even
> though the pressure never got too high. Because you say the
> noise was related to engine speed it is also possible that you
> had a catastrophic compressor failure. The noise is gone now
> probably because there is not enough Freon left in the system
> to let the compressor clutch engage. Any way, from the sounds
> of your symptoms I would highly recommend letting an
> experienced technician diagnose the problem. Naturally, because
> I was not there to hear the actual noise, It could be something
> else, but this is my best guess based on what you said.
>
> --
> Kevin Mouton
> Automotive Technology Instructor
> "If women don't find you handsome, they should at least find
> you handy"
> Red Green
>

Thanks Kevin, that makes a lot of sense and sounds logical. If I
put my nose right ON the relief valve, and nearby areas,
I -think- I can still smell it.
Hey buddy, got a quarter? <g>

Pop`