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A/C relief valve blowing open


Dan D
220, 221... whatever it takes
410/2000


Galant VR-4 org Post #: 1243610 posted 08/03/18 07:00 PM     Remind Me!  Send Private Message   Edit Post      
Twice. R134a conversion. Been good for ~ 7 years. Turned in on to find it discharged. Dye all over the relief valve on the compressor.

New relief valve. New dryer. Evacuated and charged. High side never really went over 300 psi during charging but about half way through can #3 and before it was dipping below 68F at the vents (90+ in the garage), the new relief valve opened.

The pressures on the gauges looked ok. Nothing really weird going on that I could see. I thought he relief popped over 400psi. High side lines certainly didn't hit that. Internal compressor problem? Can it do that? High internal pressure that doesn't show up on the gauge?



#410/2k

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turbofonz
Member +
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369/2000
490/2000


Galant VR-4 org Post #: 1243611 posted 08/03/18 07:34 PM     Remind Me!  Send Private Message   Edit Post      
Also looking for insight on this. Did you get new valves, or used? If new, where?



Ryan W.
91 TSi AWD - 9 sec stock bottom end and corn fed
91 Galant VR-4 - Summit White - 153/2000
91 Galant VR-4 - Summit White - 490/2000
91 Galant VR-4 - Nile Black - 369/2000
92 Galant VR-4 - Summit White - 255/1000 - [email protected] - sold

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Dan D
220, 221... whatever it takes
410/2000


Galant VR-4 org Post #: 1243620 posted 08/04/18 08:50 AM     Remind Me!  Send Private Message   Edit Post      
New valve. Available from autozone. Comes with thread adapter that fit.
Santech Part: MT1611

https://www.autozone.com/air-tools-and-accessories/air-compressor-repair-parts/santech-high-pressure-relief-valve/965994_0_0?&searchText=MT1611



#410/2k

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toybreaker Galant VR4.org Moderator
it's peace of mind at 100 mph plus
1990/2000


Galant VR-4 org Post #: 1243621 posted 08/04/18 10:58 AM     Remind Me!  Send Private Message   Edit Post      
Dan,

How long did you leave it evacuated?

Did you add oil to the system?
If so, what type did you add?

What does the compressor sound like when it's running?



the bitterness of low quality remains long after the temporary joy of a low price has faded

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Dan D
220, 221... whatever it takes
410/2000


Galant VR-4 org Post #: 1243630 posted 08/04/18 04:22 PM     Remind Me!  Send Private Message   Edit Post      
30 minutes at 29". I actually vac'd it and then had to leave it alone for a week. When I put the gauges back on it was still at 29". I turned the vacuum on for good measure while the car warmed up for 10-15 minutes before charging.

I did not add more oil. Being that the drier is only listed at 5ml, I decided to leave it alone until I had confirmed the compressor was still working and then planned to come back and inject the oil toward the end of charging. Maybe that was a fatal mistake? I wouldn't guess 6% of the system's oil missing would cause a failure that fast.

FWIW, I use ester oil. When I converted it to R134a, I had everything apart, flushed everything, drained and refilled the new compressor, and replaced the expansion valve, drier, orings.



#410/2k

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IncorpoRatedX
I'm an idiot...
501/2000


Galant VR-4 org Post #: 1243643 posted 08/05/18 09:28 AM     Remind Me!  Send Private Message   Edit Post      
Quoting Dan D:

Twice. R134a conversion. Been good for ~ 7 years. Turned in on to find it discharged. Dye all over the relief valve on the compressor.

New relief valve. New dryer. Evacuated and charged. High side never really went over 300 psi during charging but about half way through can #3 and before it was dipping below 68F at the vents (90+ in the garage), the new relief valve opened.

The pressures on the gauges looked ok. Nothing really weird going on that I could see. I thought he relief popped over 400psi. High side lines certainly didn't hit that. Internal compressor problem? Can it do that? High internal pressure that doesn't show up on the gauge?




Also looking for insight on this, having a very similar situation and replaced valve and dryer as well.



-Joshua Adventure Driven Design
1991 Galant VR-4
1999 Montero "Goldi-Locker"

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FlyingEagle Galant VR4.org Moderator
Eager Beaver


Galant VR-4 org Post #: 1243644 posted 08/05/18 09:30 AM     Remind Me!  Send Private Message   Edit Post      
You AC system should operate somewhere in the range of Low Side 25-45 PSI, and High Side 125-175+ PSI. When operating outside of that range, your system is not working properly, whether you don't have any air coming across the condenser (IE fan/s not working, plugged condenser fins and or radiator fin restrictions), a plugged TXV/pressure differential valve (the part that creates the high and low side pressure difference through restriction) or some other anomaly. When charging AC systems I have never seen the pressure gauge go any higher than roughly 100 PSI, whether charging the high side, both or low side (the preferred method unless specified), but this is with a proper machine. You have to be able to see the pressures low and high side when operating to know how the system is working.

Normally I would say to never operate a vacuum on the AC compressor while the engine is running, even if the clutch is not engaged and therefore the system is in theory not being acted upon in an unnatural state, so there is that. Could it have caused an issue, don't know.
If you have a pressure relief valve that is working as designed, you have a major high side pressure issue - no fan and high ambient temps will cause the high side of the system to soar faster than you can point a stick at the engine and make a wavy action. Try blocking the condenser with a cardboard sheet and use the gauges sometime to confirm this, it will shock you how high the pressure goes and how fast.

I am leaning towards your high side issue being a possible air flow issue - what is your fan setup? Radiator core and condenser core in tip top shape too?
If not an air flow issue, then you have a blockage or compressor problem.
Also, you might need to know how much oil is in the system, as the blowoff valve will release a decent amount of oil from the compressor housing.

Jon's questions still stand obviously, as they are good indica.tors



C53A 1 of the ~1500


Edited by FlyingEagle (08/05/18 09:34 AM)

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Dan D
220, 221... whatever it takes
410/2000


Galant VR-4 org Post #: 1243649 posted 08/06/18 11:15 AM     Remind Me!  Send Private Message   Edit Post      
The chart I have for R134A says high side of 275-300 at 95F ambient which it was in the garage that day but I remember being closer to 240-250 when I charged it last time (~2.5 times ambient temp).

It wanted to go above 300 until the condenser fan would kick into high gear at 300psi like it was supposed to and then it would come back below 300psi right away. That was at 1800prm. Radiator and condenser are in good shape. All replacement parts without a lot of miles.

I wasn't paying really close attention during the first two canisters but thinking back, it might have already been 250+ before 1.5 cans were in. If it shot that high, that fast then a blockage maybe? I guess it's time to pull it all apart and see.



#410/2k

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FlyingEagle Galant VR4.org Moderator
Eager Beaver


Galant VR-4 org Post #: 1243671 posted 08/08/18 02:49 PM     Remind Me!  Send Private Message   Edit Post      
What is the Capacity of R12/R134A the system calls for, TOTAL ?

What is contained within a can of your topup R134A/substitute?

IF you overfill the system without knowing ... it can have strange effects, none of which I have experienced first hand but have suspected on at
least one car, that we sent to a Freon recycler/flusher before we even touched the car. You know the kind of car that comes in and the cust
states they topped it up? Then the questions begin and you want to know more before you contaminate your machine and every other fill up for
other customers who would get their R134a fill following repair from your now mixed tank.

Here is a link to the AC performance test procedure - this is the factory manual 89-93 Galant IIRC:

Chapter 55

http://www.lilevo.com/mirage/89-93%20Mitsubishi%20Galant%20Eagle%20GTX%20BE%20Service%20Manual%20.PDF/89-93BE.PDF

Oddly enough they used a can refill procedure but some of the aftermarket cans, are a pierce pin style can after attaching, and remove the whole kit once you reach a max cold recorded temps at the specific dash vent during the fill but it can be very easy to overfill I think. Very unspecific, when machines can do the fill to well within the tolerance of what the fill intended was, as set to on the machine.

They mentioned to check the sight glass during the fill - this can indicate the presence of air bubbles, which can be an indicator of low charge, but by the same token can be 100% misleading depending on the temperature at which the view is made!!! I just did some reading and unless I am holy wrong, at certain low and high ambient temps you can get some separation inside a completely filled (READ proper charge level) system, so those bubbles would only go away inside of a set ambient temp range. For those reading this, be aware of this condition.

I would like to know if your AC fan starts the moment you engage your AC system ? I am trying to find the description and operation for the GVR4 AC system, as my Colt was similar but was not wired the same way, nor operates exactly the same way under all circumstances even though it has a resistor setup in use. Essentially my AC fan comes on immediately, when the AC is selected and clutch engages, and under higher pressure in the system - reaches a switch point - at which the fan gets moved to a non resistor setting and is allowed full battery voltage. I am unsure of how much a pressure change is read between the chart for R12 system charge and what occurs with R134a or substitute in the system, so that is in regards to what you should see at your high and low side connection points for gauges/fill/removal. Also, you have to be sure of how much system oil is in play both when you the system was operating properly (for the last few years) and now that you have had a blow off condition at the compressor - this is where most of the oil sits, but not all. You have definitely lost a portion of your system oil.

It also seems that for a fill of R134a, you may have to fill to a percentage of the complete system refrigerant capacity due to the pressures that R134a works at, or so this particular site is commenting on:

https://www.aa1car.com/library/retrofit.htm

I would honestly like to know what people are filling their converted system to, and at what pressures they operate. The gas is supposed to operate in certain pressure ranges, otherwise the change of state is insufficient (just like a non-working metering valve or blocked/partly blocked orifice tube).

I relayed system pressures from OEM R134a equipped vehicles, so I 100% want to be correct on the pressures you SHOULD be seeing with your converted setup.


Edited by FlyingEagle (08/08/18 03:29 PM)

Posts: 1582 | From: THE Ottawa | Member Since: 03/05/05 | IP: (68.171.77.46) | Report this post to a Moderator

FlyingEagle Galant VR4.org Moderator
Eager Beaver


Galant VR-4 org Post #: 1243672 posted 08/08/18 03:17 PM     Remind Me!  Send Private Message   Edit Post      
If the manual I stated is correct, your system pressures regulate items like this:

Compressor switch off because pressure is = or < 30 PSI system pressure - low charge
Compressor switch off because pressure is = or > 384 PSI system pressure - fan not working on one or more modes (low or high), blockage, kinked line, etc

Your discharge port on the compressor will likely be set higher than this, but if it is spring operated ... things can weaken, not assuming there are not any other system issues causing abnormally high pressures.

Pressure switch installed above the high pressure pipe is for control of the radiator fan and condenser fan and regulates them in LO and HI modes.
It will have no continuity below 213 PSI.
Continuity exist from 256 PSI and up.

There is a refrigerant temperature sensor mounted on the compressor, this is thermal switch of some sort that is likely a clutch cutout device as well - basically a break in the line to the clutch above a certain temperature.

Compressor clutch cut out exists also, when the AC temp switch on the coolant thermostat housing reaches 239 degrees Celcius, or you rev beyond a certain preset RPM in the ECU prom code setup - somewhere north of 5000 RPM to save the compressor internals.



C53A 1 of the ~1500

Posts: 1582 | From: THE Ottawa | Member Since: 03/05/05 | IP: (68.171.77.46) | Report this post to a Moderator

FlyingEagle Galant VR4.org Moderator
Eager Beaver


Galant VR-4 org Post #: 1243675 posted 08/08/18 03:27 PM     Remind Me!  Send Private Message   Edit Post   
Here are some system test procedures as copied from the manual Chapter 55

DUAL PRESSURE SWITCH
The dual-pressure switch is a combination of the low-pressure
switch (for checking the quantity of refrigerant) and the
high-pressure switch (for prevention of overheating); it is
installed in the receiver, and, when the pressure becomes
approximately 210 kPa (30 psi) or lower, the compressor stops,
thus preventing the compressor from being damaged by heat.
When the pressure reaches 2,700 kPa (384 psi) or higher, the
compressor stops, thus preventing overheating. There is
generally no necessity for inspection; if, however, an unusual
condition, such as non-operation of the compressor is encountered,
check by following the procedures below.
(1) Turn back the adaptor valve handle all the way and install it
to the high pressure side service valve.
(2) With the gauge manifold low pressure service valve closed,
connect the gauge manifold low pressure side charging
hose to the adaptor valve.
(3) Tighten the adaptor valve handle and open the service
valve.
(4) If there is continuity between the dual pressure switch
terminals when the high pressure side pressure is at level
of dual pressure switch ON condition shown to the left, the
switch is functioning normally. If not, replace the switch.
PRESSURE SWITCH
The pressure switch (installed above the high-pressure pipe)
is for control of the condenser and the radiator fan; it
regulates the fan in two steps (LO and HI).
If there is a problem such as non-operation of the condenser
fan, check by following the procedures described below.
(1) Install the gauge manifold, and then switch the air conditioning
to the operation mode.
(2) Check for continuity of the pressure switch.


TEST PROCEDURES
SYSTEM TEST
(1) Turn back the adaptor valve handle all the way and install
each adaptor valve to the high and low pressure service
valves.
(2) With the gauge manifold high and low pressure valves
closed, connect the gauge manifold to the high and low
pressure adaptor valves.
(3) Tighten the adaptor valve handle to open the service valves
for checking the pressure.
(4) If a pressure of 294 to 392 kPa (43 to 59 psi) is indicated on
the suction gauge side and a pressure of approx. 1,961 kPa
(284 psi) is indicated on the discharge gauge side, it is
suspected that air is present in the air conditioning system.
Discharge the system, evacuate and recharge with specified
amount of refrigerant.
(5) During operation of the air conditioning cold air may stop
flowing after the elapse of time and this state is maintained
before cold air flows out again. If cold air stops flowing out
with negative pressure indicated on the suction gauge side
and a pressure of 588 to 980 kPa (85 to 142 psi) indicated
on the discharge gauge side, it is suspected that water is
present in the air conditioning system.
Discharge the system. Replace receiver drier. Evacuate and
check for leaks, and recharge with specified amount of
refrigerant.


COMPRESSOR
(I) Turn back the adaptor valve handle all the way and install
each adaptor valve to the high and low pressure service
valves.
(2) With the gauge manifold high and low pressure valves
closed, connect the gauge manifold to the high and low
pressure adaptor valves.
(3) Tighten the adaptor valve handle to open the service valves
for checking the pressure.
(4) If a pressure of approx. 490 kPa (71 psi) is indicated on the
suction gauge side and a pressure of approx. 883 kPa (128
psi) is indicated on the discharge gauge side, the compressor
has abnormal compression. Replace the compressor.


SIGHT GLASS REFRIGERANT LEVEL TEST
The sight glass is a refrigerant level indicator. To check the
refrigerant level, clean the sight glass and start the vehicle
engine. Push the air conditioning button to operate the
compressor, place the blower switch to high and move the
temperature control lever to extreme left. After operating for a
few minutes in this manner, check the sight glass.
(1) If the sight glass is clear, the magnetic clutch is engaged,
the compressor discharge line is warm and the compressor
inlet line is cool; the system has a full charge.
(2) If the sight glass is clear, the magnetic clutch is engaged
and there is no significant temperature difference between
compressor inlet and discharge lines; the system
has lost some refrigerant.
(3) If the sight glass is clear and the magnetic clutch is
disengaged; the clutch is faulty or, the system is out of
refrigerant. Perform low pressure switch test to determine
condition. Check low pressure switch, and clutch coil for
electrical continuity.
(4) If the sight glass shows foam or bubbles, the system
could be low on charge. Occasional foam or bubbles are
normal when the ambient temperature is above 43C
(110F) or below 21C (70F).
Adjust the engine speed to 1,500 rpm. Block the air-flow
thru the condenser to increase the compressor discharge
pressure to 1,422 to 1,520 kPa (206 to 220 psi). If sight
glass still shows bubbles or foam, system charge level is
low.
The refrigerant system will not be low on charge unless
there is a leak. Find and repair the leak. If the leak can be
repaired without discharging the system an oil level check
is not necessary. Use the procedure for correcting low
refrigerant level found in the Refrigerant System Service
Procedure Section.



C53A 1 of the ~1500


Edited by FlyingEagle (08/08/18 03:31 PM)

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