Honda Car Forum

We are having AC problems with a 2000 Honda CRV.

We just did a successful vacuum and leak test,
then recharged the system with 134a.

At a constant 3000 RPMs, and with a set of AC gages attached
to the low & high ports, the AC system does this:

1. The low pressure gauge rises in pressure until the high
limit (low side) switch disengages the AC clutch. The high pressure gauge
is within limits at this time.

2. When the low pressure gage returns to safe pressure, the AC
clutch engages. This time the high side pressure gage begins to climb
until it reaches the high side limit in PSI, and the AC clutch disengages.
The high side pressure declines to a safe PSI and the AC clutch
again engages. Now go back to #1 above and start the low pressure side
rising to the upper limit. It is a continuous loop.

The above is an endless loop of reaching max low PSI, shut off, reaching
max high PSI, shut off, reaching max low PSI, shut off ...

Even at a steady 3000 RPM, the above constant cycling does not do a
satisfactory job of cooling the car.

What's the problem?

THANKS,
Gene

Why did you have to vacuum your system? Did you make sure no air got into
the system by bleeding a little refigerant gas from the servicing lines?
Did the AC have a problem before all of your work? Did you put the
absolute correct amount of R-134A and oil into the system? The answers to
these questions may help us figure out what's going on here.

THANKS !!

> Why did you have to vacuum your system?
The high pressure valve became defective and leaked out
the 134a. We replaced both valves, and the system is 100%
closed now.

>Did you make sure no air got into the system by bleeding a little
refigerant gas from the servicing lines?
Yes, cleared all lines.

> Did the AC have a problem before all of your work?
Yes, the very same problem. Pulling it down, checking for leaks, and
refilling it with two cans of 134a did not help. Still having the SAME
problems as when it was previously full of 134a. The leaking valve was
just a good time to try & fix it. (It's my kid's car.)

>Did you put the absolute correct amount of R-134A and oil into the
system?
I put in two cans, which should be more than enough. I was having the same
high pressure problem when putting in the two cans - had to do it over a
full day, so as to not exceed pressures on the low side. Not sure if I had
to do that, but it made me feel better:-)


>The answers to these questions may help us figure out what's going on
>here.
THANKS for al the kind assistance - I need it.


*******************

I'm pretty sure the problem is that the high pressure side immediatelly
rises and triggers the high pressure sensor. The question is, why
does the pressure on the high side rise, and keep going until it
trips the high pressure sensor?

Something clogged?
Bad compressor?

THANKS,
Gene

************ COPY ********

Thanks.

I agree with your best guess, that it could be some blockage on the high
side.

The car was recently purchased used by my kids, so we have no historical AC
data.

I did three similar AC compressor replacements with these same gauges in the
last month and all went 100% successfully - so I am pretty sure the gauges
are OK.

I pulled ~ 25-26 vacuum for ~ an hour with both low & high sides open.
That should have been enough to get the moisture.

Because I am doing it myself, here is the approach that I like, and will
probably
do in this case, assuming the problem persists.

1. Go to a local salvage yard & find the best AC compressor from a "wrecked"
car.
It must come from a reputable yard & have an unconditional 100% return for
90 days.
To test it, I pour in an ounce of the appropriate oil into the compressor,
turn it over by
hand to check compression a few times, then pour out the oil onto a clean
napkin.
It must have good compression & no foreign matter in the oil. Next I test
the clutch with
a 12VDC+ to the clutch pin. Finally, I spin the pulley and use a stethoscope
to listen
to the bearing free wheel. If all of the above are OK, I install said AC
compressor.
Here is my logic for the above:
a. Factory AC compressor are WAY too expensive.
b. The lower priced new compressors are made in China.
c. The rebuilt compressors are the patched trash that were returned.
d. The used ones per above are the only ones that are in good condition &
low priced. So far, I have never had a bad one. Just check them out first.


2. Buy all new O rings, seals, dryer, filter, etc. - I even replace the
low/high port valves.

3. Remove the old compressor, etc. & flush the system

4. Install the used compressor with oil, etc. , do a complete vacuum & leak
test - then
fill with 134a.

The TOTAL out-of-pocket cost runs from $100 to $250, depending on the car.

In that it is so inexpensive to just do it right, this is probably what is
best for this Honda.
It's really not worth the time and effort to trace down a potential clogged
point in the system
for $200 or so.

However, I really would like to know what the problem is with this Honda,
I'm just currious:-)

THANKS,
Gene







"Comboverfish" <comboverfish@yahoo.com> wrote in message
news:1186061575.678354.226280@r34g2000hsd.googlegr oups.com...
> On Aug 1, 11:29 pm, "Gene" <ge...@wildblue.net> wrote:
>> "Comboverfish" <comboverf...@yahoo.com> wrote in message
>>
>> news:1185995371.924968.290650@x35g2000prf.googlegr oups.com...
>>
>>
>>
>> > On Jul 31, 2:13 pm, "Gene" <ge...@wildblue.net> wrote:
>> >> We are having AC problems with a 2000 Honda CRV.
>>
>> >> We just did a successful vacuum and leak test,
>> >> then recharged the system with 134a.
>>
>> >> At a constant 3000 RPMs, and with a set of AC gages attached
>> >> to the low & high ports, the AC system does this:
>>
>> >> 1. The low pressure gauge rises in pressure until the high
>> >> limit (low side) switch disengages the AC clutch. The high pressure
>> >> gauge
>> >> is within limits at this time.
>>
>> >> 2. When the low pressure gage returns to safe pressure, the AC
>> >> clutch engages. This time the high side pressure gage begins to climb
>> >> until it reaches the high side limit in PSI, and the AC clutch
>> >> disengages.
>> >> The high side pressure declines to a safe PSI and the AC clutch
>> >> again engages. Now go back to #1 above and start the low pressure side
>> >> rising to the upper limit. It is a continuous loop.
>>
>> >> The above is an endless loop of reaching max low PSI, shut off,
>> >> reaching
>> >> max high PSI, shut off, reaching max low PSI, shut off ...
>>
>> >> Even at a steady 3000 RPM, the above constant cycling does not do a
>> >> satisfactory job of cooling the car.
>>
>> >> What's the problem?
>>
>> >> THANKS,
>> >> Gene
>>
>> > Please give the following in actual numbers:
>>
>> > 1) your interpretation of low side unsafe pressure
>>
>> I think it shut off at ~ 110PSI or a little less
>>
>>
>>
>> > 2) high side cut-off limit
>>
>> It was near 400PSI when it shuts off
>>
>>
>>
>> > 3) high side safe turn-on point
>>
>> Can't remember,but it was > 150PSI
>>
>> > Also, what exactly is a "high limit (low side)" switch?
>>
>> When the low side gets near the 110PSI area, it shuts off.
>>
>>
>>
>> > I'm thinking you don't know how this system operates. I'll be glad to
>> > help if you fill in the above data.
>>
>> LOL - I definitelly do not understand this one.
>> I would expect it to run at ~ 30-50 PSI on the low side and
>> about 150 to 200 PSI on the high side, but not sure ?
>>
>> Thanks,
>> Gene
>
> I said that not to be rude, but because you suspected high low side
> pressures as a cause for the system to shut down. This system (from
> the factory, atleast) has only one pressure switch that can control
> the compressor's engagement. It is a dual pressure type switch
> located on the high pressure line (the smaller diameter line) near the
> front of the vehicle, located in or near the receiver drier but I
> don't remember for sure. This switch will shut down the compressor at
> about 450 psi and also if the pressure drops below about 30 psi.
> There will be a "hysteresis range" of pressure around those points
> with this type of switch; this will cause it to stay off for a while
> after it passes back into the acceptable range of operation. Perhaps
> this hysteretic action is what you were describing.
>
> The bad news is that your symptoms do not lead to one conclusion. It
> doesn't sound like the dual pressure switch is causing the cutoff
> every time, and the gauges' behaviors don't lead me to a solid
> conclusion. I think I would have to see it for myself, or assume
> there is a moving piece of blockage in the high side, either in the
> condenser or the drier. Perhaps you have too much oil in the system
> too.
>
> If both gauges went high at the same time, climbing gradually, I would
> say it is probably overcharged. How much R134a by weight did you
> install? Did you reference the refrigerant charge sticker underhood?
> To what indicated vacuum and for how long did you evacuate?
>
> If the high side all-of-a-sudden pegged hard and the low side rose
> quickly afterwards I would suspect high side blockage. Condensers are
> the most common area for this manner of restriction.
>
> Another though is an inaccurate gauge set or the valves were open or
> leaking internally (along with an A/C problem).
>
> Toyota MDT in MO
>
"Gene" <genes@wildblue.net> wrote in message
news:TOLri.48$ug2.326837@news.sisna.com...
> We are having AC problems with a 2000 Honda CRV.
>
> We just did a successful vacuum and leak test, then recharged the system
> with 134a.
>
> At a constant 3000 RPMs, and with a set of AC gages attached
> to the low & high ports, the AC system does this:
>
> 1. The low pressure gauge rises in pressure until the high
> limit (low side) switch disengages the AC clutch. The high pressure gauge
> is within limits at this time.
>
> 2. When the low pressure gage returns to safe pressure, the AC
> clutch engages. This time the high side pressure gage begins to climb
> until it reaches the high side limit in PSI, and the AC clutch disengages.
> The high side pressure declines to a safe PSI and the AC clutch
> again engages. Now go back to #1 above and start the low pressure side
> rising to the upper limit. It is a continuous loop.
>
> The above is an endless loop of reaching max low PSI, shut off, reaching
> max high PSI, shut off, reaching max low PSI, shut off ...
>
> Even at a steady 3000 RPM, the above constant cycling does not do a
> satisfactory job of cooling the car.
>
> What's the problem?
>
> THANKS,
> Gene
>
>
>
>
>
>
>
>