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Re: How to diagnose a bad expansion valve?

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  #1  
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Chris Mauritz
 
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Default Re: How to diagnose a bad expansion valve? - 06-30-2003 , 06:34 PM






"The Bathtub Admiral" <admiral (AT) escape (DOT) ca> wrote

Quote:
"Daniel J. Stern" <dastern (AT) engin (DOT) umich> wrote in message
news:Pine.SOL.4.44.0306301258290.18508-100000 (AT) alumni (DOT) engin.umich.edu...
On Mon, 30 Jun 2003, The Bathtub Admiral wrote:

Retrofit included new filter drier, 8oz ester 100, vacuumed system
down
to
29 inches for 30 min.

H'm. What'd you do about the oil in the compressor? Did you flush the
system?

No, the system was low on charge, barely recoverable, no flush was
performed. How critical is it to remove the old mineral oil?
It's not critical to remove all the mineral oil if you add more oil that is
compatible with it, 134a, and your system. In a perfect world you would use
compressed air or some other method to blow as much old oil out of the
system as you could, followed by solvent, followed by evacuation. After
evac, you can then add the refrigerant oil. I normally add mine with one of
those little piston tools through the low side shrader valve so I don't have
to break the system open.

Quote:
134a, but it reported air in the system, whatever that means,

Noncondensibles (air, water and other contaminants) in the system
severely
reduce its efficiency. Air in the system means it was not sufficiently
or
properly evacuated, or that air was let back in due to improper charging
procedure after a proper evacuation.

can't be more specific. Also in the retrofit, one can of seal
conditioner

Usually not a good idea.

Im toying with the idea that there is some sort of oobstruction in the
expansion valve, the type of seal condition wasn't the cliplight expoy
shit,
but im still worried that the sealant might be causing some sort of
problem.
One more thing...when i recieved the reciever drier from the jobber, the
seals on it were open, meanign that it was exposed to ambient air, i
contacted everco and they said not to worry as the drier had a rediculous
amount of capacity, like the ability to absorb a pint of water.
Your jobber either lied to you or just doesn't know what he or she is doing.
The receiver/drier should be sealed from ambient air. I'd make them take it
back and put another one on the car. You can use that opportunity to change
the expansion valve at the same time.

Cheers,

C






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  #2  
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Chip Stein
 
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Default Re: How to diagnose a bad expansion valve? - 06-30-2003 , 11:47 PM






"The Bathtub Admiral" <admiral (AT) escape (DOT) ca> wrote

Quote:
Have a 90 Chrysler G body, need to know how to diagnose a bad expansion
valve, low side pressure was 35 and high was 250, but outlet temp with
blower on high was only 15 degrees Fahrenheit off of ambient. I suspect a
bad expansion valve, but do not know how to properly diagnose a bad
expansion valve. Was retrofitted to 134a last summer.
do the fans work???? if so you may have a stopped up reciever due
to the sealer. most often when the h-block goes on a chrysler the low
side goes into retard.
replace the reciever and re-charge.
Chip


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  #3  
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Daniel J. Stern
 
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Default Re: How to diagnose a bad expansion valve? - 07-01-2003 , 10:14 AM



On Mon, 30 Jun 2003, The Bathtub Admiral wrote:

Quote:
H'm. What'd you do about the oil in the compressor? Did you flush the
system?

No, the system was low on charge, barely recoverable, no flush was
performed. How critical is it to remove the old mineral oil?
Critical. It's extra work to remove the compressor, turn it upside down
and manually spin it until you've got all the oil out of it, and it's
certainly extra work to flush the system, but it pays large dividends both
in the short term (system performance -- the mineral oil, not being
miscible in R134a, just sits there and interferes with heat transfer) and
in the long term (compressor longevity).

Quote:
One more thing...when i recieved the reciever drier from the jobber, the
seals on it were open, meanign that it was exposed to ambient air

[TILT]
This is completely unacceptable and is a very likely cause of your
system's low performance.

Quote:
contacted everco and they said not to worry as the drier had a rediculous
amount of capacity, like the ability to absorb a pint of water.
Horseshit. It does not. And even if it did, it was saturated before you
even put it in the system.

DS



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  #4  
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bobby
 
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Default Re: How to diagnose a bad expansion valve? - 07-01-2003 , 01:11 PM





The Bathtub Admiral wrote:
Quote:
Have a 90 Chrysler G body, need to know how to diagnose a bad expansion
valve, low side pressure was 35 and high was 250, but outlet temp with
blower on high was only 15 degrees Fahrenheit off of ambient. I suspect a
bad expansion valve, but do not know how to properly diagnose a bad
expansion valve. Was retrofitted to 134a last summer.
Please post your solution once you get there as I have been watching this
thread and fighting a similar problem in an 89 Ford van with dual that had been
converted to 134a prior to my purhcase. My plans were to replace the
reciever/dryer and front orfice tube and evacuate, but left the receiver/dryer
in place after fighting trying to get hands and tools into the tiny spaces Ford
gives you on the E150 vans. Connected vacuum pump with engine idled (idea
being get everything hot under the hood and maybe drive off a little more
moisture) for 1 hour and gauges read 30 in vac. Recharged to 35 psi low side,
235 psi high side at about 2000 rpm (took 48oz). Also added seal conditioner.
Monitored as adding and also only getting 15 - 20 degrees cooler than ambient.

thanks
bb


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  #5  
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Daniel J Stern
 
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Default Re: How to diagnose a bad expansion valve? - 07-10-2003 , 05:28 PM



On Thu, 10 Jul 2003, Oppie wrote:

Quote:
Brought it to a friend's shop to recharge. I was going to switch to HC134A
but was recommended to use "FR-12". Supposedly, this is a new mixture that
is more compatible with systems that were designed for R12.
Not really. It's R134a with a slug of something else to try to move oil
back to the compressor.

Quote:
The FR-12 is
compatible with new OR old oils
Not very *well* compatible with either.

Quote:
and has nearly the same pressures and
boiling points as R12.
Nope, not even close. Nearly identical to R134a.

Quote:
The down side is that while FR-12 costs about the same as HC134A, it is not
available to unlicenced techs. Works good though even with the tired old
compressor. (couldn't afford to replace it then)
FR-12 is legal, but I hope your tech properly and legally retrofitted the
system, complete with FR12 service ports and FR12 labelling. The problem
with ALL refrigerants other than R12 and R134a, regardless of their
performance or compatibility, is that none of them is nearly as widely
handled and serviced as 12 and 134a. If you have a problem in the future,
many shops will charge a very hefty fee or simply refuse to work on your
system because it contains a nonstandard refrigerant.

DS



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  #6  
Old   
Oppie
 
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Default Re: How to diagnose a bad expansion valve? - 07-10-2003 , 05:33 PM



I replaced the hoses on my '89 V'ger since they were all leaking oil through
the rubber. There was no gas pressure left in the system and barely any oil
left in the compressor. While I had everything apart, I also replaced the
expansion valve and receiver/dryer.

Brought it to a friend's shop to recharge. I was going to switch to HC134A
but was recommended to use "FR-12". Supposedly, this is a new mixture that
is more compatible with systems that were designed for R12. The FR-12 is
compatible with new OR old oils and has nearly the same pressures and
boiling points as R12.

The down side is that while FR-12 costs about the same as HC134A, it is not
available to unlicenced techs. Works good though even with the tired old
compressor. (couldn't afford to replace it then)


For the OP, if the blower dicsharge was only 15 deg below ambient, was the
compressor running full time or cycling? also what was the suction line
temperature coming out of the expansion valve and at compressor? If the
suction temperature is too low, there may be a blockage of airflow through
the evaporator. Also look at the sight glass on the top of the
receiver/dryer. should be mostly clear liquid flowing and a few bubbles.
More bubbles expected at higher ambient temperatures.
Oppie
--
For correct response address, remove one after boppie
=========
"The Bathtub Admiral" <admiral (AT) escape (DOT) ca> wrote

Quote:
Have a 90 Chrysler G body, need to know how to diagnose a bad expansion
valve, low side pressure was 35 and high was 250, but outlet temp with
blower on high was only 15 degrees Fahrenheit off of ambient. I suspect
a
bad expansion valve, but do not know how to properly diagnose a bad
expansion valve. Was retrofitted to 134a last summer.





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  #7  
Old   
Oppie
 
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Default Re: How to diagnose a bad expansion valve? - 07-11-2003 , 08:22 AM



Live and learn :-)
Thanks for the input.

--
---
"Daniel J Stern" <dastern (AT) engin (DOT) umich> wrote

Quote:
On Thu, 10 Jul 2003, Oppie wrote:

Brought it to a friend's shop to recharge. I was going to switch to
HC134A
but was recommended to use "FR-12". Supposedly, this is a new mixture
that
is more compatible with systems that were designed for R12.

Not really. It's R134a with a slug of something else to try to move oil
back to the compressor.

The FR-12 is
compatible with new OR old oils

Not very *well* compatible with either.

and has nearly the same pressures and
boiling points as R12.

Nope, not even close. Nearly identical to R134a.

The down side is that while FR-12 costs about the same as HC134A, it is
not
available to unlicenced techs. Works good though even with the tired old
compressor. (couldn't afford to replace it then)

FR-12 is legal, but I hope your tech properly and legally retrofitted the
system, complete with FR12 service ports and FR12 labelling. The problem
with ALL refrigerants other than R12 and R134a, regardless of their
performance or compatibility, is that none of them is nearly as widely
handled and serviced as 12 and 134a. If you have a problem in the future,
many shops will charge a very hefty fee or simply refuse to work on your
system because it contains a nonstandard refrigerant.

DS





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