A/c. Checking efficiency.

'94 E34 525i SE.
Does anyone know the specific checking procedure for this model.
I understand the procedure involves checking the inlet air temperature,
against the ambient air temperature, but I have no idea what the
differential temperature should be. The a/c is working, but I feel it could,
or should, be cooler.
Bentley's is no help as it only deals with the mechanics of the a/c system.
Maybe I'm expecting too much, so I'd like to check it myself before spending
any money on having it checked by an a/c specialist.
Anyone?
TIA.
Mike.

On 7/3/2006 10:49 AM, Mike G went clickity-clack on the keyboard and
produced this interesting bit of text:
> '94 E34 525i SE.
> Does anyone know the specific checking procedure for this model.
> I understand the procedure involves checking the inlet air temperature,
> against the ambient air temperature, but I have no idea what the
> differential temperature should be. The a/c is working, but I feel it
> could, or should, be cooler.
> Bentley's is no help as it only deals with the mechanics of the a/c system.
> Maybe I'm expecting too much, so I'd like to check it myself before
> spending any money on having it checked by an a/c specialist.

I don't know any mechanic that checks the AC capability by doing
anything other than sticking a thermometer into a vent and turning the
AC and fan on full. Mine gets pretty darn cold, about 36 degrees F.
There's no real magic to it. FWIW, I have a '94 E34 (530i). Yours
should be pretty much the same. If it's not blowing cold, then it may
be that you need the system recharged. If it's the first time it's been
recharged, then you don't need to worry about leaks, but if it has to be
recharged soon after, then you should get it checked out.

The top of the receiver/dryer unit has a little window on it. While the
AC is running, you should see bubbles in the window. If you don't, then
it's probably low on refrigerant and you'll have to take it in. I don't
think R134a is available in stores like Freon was.

--
Baseball is ninety percent mental and the other half is physical. - Yogi
Berra

Please check your procedure. Bubbles in the refrigerant means you're
possibly low. Allow the system to run for at least 10 minutes and check the
sight glass. If you see bubbles, add refrigerant until the bubbles just
disappear. A sight glass that looks empty most likely is full of
refrigerant. Otherwise the low pressure cutoff would have stopped the
compressor from self-destructing. If you don't hear the compressor cycling,
then most likely you're low of refrigerant.

"Voinin" > wrote in message
...
> On 7/3/2006 10:49 AM, Mike G went clickity-clack on the keyboard and
> produced this interesting bit of text:
> > '94 E34 525i SE.
> > Does anyone know the specific checking procedure for this model.
> > I understand the procedure involves checking the inlet air temperature,
> > against the ambient air temperature, but I have no idea what the
> > differential temperature should be. The a/c is working, but I feel it
> > could, or should, be cooler.
> > Bentley's is no help as it only deals with the mechanics of the a/c
system.
> > Maybe I'm expecting too much, so I'd like to check it myself before
> > spending any money on having it checked by an a/c specialist.
>
> I don't know any mechanic that checks the AC capability by doing
> anything other than sticking a thermometer into a vent and turning the
> AC and fan on full. Mine gets pretty darn cold, about 36 degrees F.
> There's no real magic to it. FWIW, I have a '94 E34 (530i). Yours
> should be pretty much the same. If it's not blowing cold, then it may
> be that you need the system recharged. If it's the first time it's been
> recharged, then you don't need to worry about leaks, but if it has to be
> recharged soon after, then you should get it checked out.
>
> The top of the receiver/dryer unit has a little window on it. While the
> AC is running, you should see bubbles in the window. If you don't, then
> it's probably low on refrigerant and you'll have to take it in. I don't
> think R134a is available in stores like Freon was.
>
> --
> Baseball is ninety percent mental and the other half is physical. - Yogi
> Berra

On 7/3/2006 12:49 PM, John went clickity-clack on the keyboard and
produced this interesting bit of text:
> Please check your procedure. Bubbles in the refrigerant means you're
> possibly low. Allow the system to run for at least 10 minutes and check the
> sight glass. If you see bubbles, add refrigerant until the bubbles just
> disappear. A sight glass that looks empty most likely is full of
> refrigerant. Otherwise the low pressure cutoff would have stopped the
> compressor from self-destructing. If you don't hear the compressor cycling,
> then most likely you're low of refrigerant.

Thank you for the correction. It's been a while since I messed with AC
myself, so I got it backwards.

--
A bather whose clothing was strewed
By breezes that left her quite nude,
Saw a man come along
And, unless I'm quite wrong,
You expected this line to be lewd.

"John" > wrote in message
.. .
> Please check your procedure. Bubbles in the refrigerant means you're
> possibly low. Allow the system to run for at least 10 minutes and check
> the
> sight glass. If you see bubbles, add refrigerant until the bubbles just
> disappear. A sight glass that looks empty most likely is full of
> refrigerant. Otherwise the low pressure cutoff would have stopped the
> compressor from self-destructing. If you don't hear the compressor
> cycling,
> then most likely you're low of refrigerant.

As I said in my post. The a/c seems to be working properly.
But, as far as I can see, and Bentleys would appear to confirm it, the a/c
system in my car doesn't have a sightglass.
My Celica has one, so I know what to look for.

I know a thermometer in the outlet will show it's blowing cool air. I'm just
wondering if it's as cool as it should be. My feeling is that it should be
cooler.
To be comfortable on a hot day, around 30C it has to be running at max.
OTOH, admitted the a/c in my Celica is an R12 system which in general are
more efficient, max on a hot day would give me goosebumps.
Mike.

In article >,
Mike G > wrote:
> To be comfortable on a hot day, around 30C it has to be running at max.

My E34 was the same. No climate control on that - just off/on AC. My old
Rover with a Delco AC system is much more powerful - but you notice the
power it takes from the engine more.

--
*The sooner you fall behind, the more time you'll have to catch up *

Dave Plowman London SW
To e-mail, change noise into sound.

I have noticed that my E30 (a few years older than your car)
converted to R134a runs about 25 degrees differential. When I press
the switch to recirculate, the differential increases to almost 40
degrees. I am in Florida and this time of year it's nice to look down
and see the thermometer that's hanging in the vent read around 45
when it's damn near 90 outside. BTW - All readings are in fahrenheit
for those that are wondering

On Mon, 3 Jul 2006 21:56:51 +0100, "Mike G" >
wrote:

>
>"John" > wrote in message
. ..
>> Please check your procedure. Bubbles in the refrigerant means you're
>> possibly low. Allow the system to run for at least 10 minutes and check
>> the
>> sight glass. If you see bubbles, add refrigerant until the bubbles just
>> disappear. A sight glass that looks empty most likely is full of
>> refrigerant. Otherwise the low pressure cutoff would have stopped the
>> compressor from self-destructing. If you don't hear the compressor
>> cycling,
>> then most likely you're low of refrigerant.
>
>As I said in my post. The a/c seems to be working properly.
>But, as far as I can see, and Bentleys would appear to confirm it, the a/c
>system in my car doesn't have a sightglass.
>My Celica has one, so I know what to look for.
>
>I know a thermometer in the outlet will show it's blowing cool air. I'm just
>wondering if it's as cool as it should be. My feeling is that it should be
>cooler.
>To be comfortable on a hot day, around 30C it has to be running at max.
>OTOH, admitted the a/c in my Celica is an R12 system which in general are
>more efficient, max on a hot day would give me goosebumps.
>Mike.

"Psycho" > wrote in message
...
> I have noticed that my E30 (a few years older than your car)
> converted to R134a runs about 25 degrees differential. When I press
> the switch to recirculate, the differential increases to almost 40
> degrees. I am in Florida and this time of year it's nice to look down
> and see the thermometer that's hanging in the vent read around 45
> when it's damn near 90 outside. BTW - All readings are in fahrenheit
> for those that are wondering

Thanks. That's the sort of info I'm after.
90 F is about the temperature we have in the south of england at the mo.
Mine is a R134a system, but I very much doubt that I'm getting those sort of
differentials.
It gives me a guide of what might be possible if it's as efficient as it
should be.
Mike.

"Dave Plowman (News)" > wrote in message
...
> In article >,
> Mike G > wrote:
>> To be comfortable on a hot day, around 30C it has to be running at max.
>
> My E34 was the same. No climate control on that - just off/on AC. My old
> Rover with a Delco AC system is much more powerful - but you notice the
> power it takes from the engine more.

What gas did your E34 use?
AIUI, the changeover to R134a was around the early 90's.
Is the Rover running on R12, or one of the so-called compatible
refridgerants, or has it been converted to run on R134a?.
R12 is a more efficient gas than R134a, so that could explain the
difference.
What's the latest on your top-up kit BTW?
Might be something I'll consider using, if my system does prove to be down
on performance.
Mike.

In article >,
says...
> I know a thermometer in the outlet will show it's blowing cool air. I'm just
> wondering if it's as cool as it should be. My feeling is that it should be
> cooler.
>
>

That's why you need to measure with a thermometer to see if it is as
cool as it should be.

--
Peter Aitken