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Expansion valve; Expansion valve
Topic Started: Jun 19 2018, 12:23 PM (207 Views)
Mrbreeze


What exactly does the expansion valve do? I tried recharging the new to me tracker and the #'s were off the charts, is this possibility a none functioning expansion valve?
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freegeo
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From the 94 fsm.

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Edited by freegeo, Jun 19 2018, 12:34 PM.
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Mrbreeze


I'am beginning to believe I may have a bad expansion valve, the low and high pressures are freaking me out, and it's not really cooling.. the high pressure line is hotter than shit, and the low pressure line is very warm...
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freegeo
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Mrbreeze
Jun 19 2018, 12:40 PM
I'am beginning to believe I may have a bad expansion valve, the low and high pressures are freaking me out, and it's not really cooling.. the high pressure line is hotter than shit, and the low pressure line is very warm...
Geogonfa helped me with my AC install. I replaced a number of things on my system, just due to them being old and the system had been open to air for a while.

If you can post some pictures of your pressures, he might be able to help you as time permits.

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geogonfa
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Was anything done to the system?
how much freon did you add, if any?
low and high side pressures?
when you shut down the system did the pressures equalize?
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Mrbreeze


Ok, as some of you know, I work graveyard, and not always able to get to things right away, so this is what I've done, I relieved the pressure in the system, thought I would just put a can of 134 in and see what happened, I didn't put the vacuum pump on to draw and hold a vacuum, just wanted to see what was going on.. the low side starts off at a nice pressure, 35psi and the high starts at 140psi.. but I can watch both sides slowly building, halfway through I turned the a/c off and the low and high side equalized around 100psi, so I continued, the pressure on the low side climbed to 60psi while the high side hit 360psi.. the pressures would continue to climb if I wanted to keep waiting, but that freaked me out enough..
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metroschultz
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Please just call me; "Schultz"

It sounds overcharged
If you have the ability, evac & fill with correct amt of Freon
if not, enlist the help of the local shop. They should be willing to evac & fill for a small fee. I charge $90, unless you need more than 2#, then it is an extra $10 per#.
Then you know the Freon level and quality is good. You can't find the issue til you know the Freon is right.
After the Freon is correct, then you can use the chart to identify any problems with the system.

you may find that this fixes your system. I have run into this many times in the shop. However, when the system is low, it probably has a leak that needs to be found, if the system was high, I usually learn that the owner filled it himself, then filled it again.

OR;

You may actually have a bad valve.
Or - a blockage elsewhere in the system.
You can find it by following the path of cooling
look for the change in temp, (warm to not warm, cool to freezing, hot to tolerable, you get the drift) that's where the blockage is.

I hope this helps,
S.
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geogonfa
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:gp
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Mrbreeze


If you read my response, I've put less than a 12o/z can of r134 back into the system, the pressures are ridiculously high, there isn't a cold section in the system, it's either warm or lava hot.. and I'am trying to figure out why.. thanks for the help though..
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blue_can
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[ *  * ]
It sounds like a possible restriction to me - if the restriction is say at the input to the compressor, the compressor will keep pumping and the pressures will keep building up on the low and high sides as the refrigerant keeps backing up. It may even be an issue with the compressor - for example if the input reed valve has snapped off and is blocking the input suction line.
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geogonfa
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Again with a few questions; :type
What year Metro are you working on?
When you turned on the a/c and the compressor was working,
did the condenser fan come on and stay on as long as the compressor was on?...
:type
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Mrbreeze


Hey geogonfa, it a new to me 95 Geo tracker, 16v 4 cyl, 5sp.. the compressor stays engaged, these things aren't set up like our Geo's.. the engine is front facing and has the fan connected to the water pump, like the old school stuff..
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metroschultz
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Please just call me; "Schultz"

Mrbreeze
Jun 21 2018, 11:05 AM
If you read my response, I've put less than a
(1) 12o/z can of r134 back into the system,
(2) the pressures are ridiculously high,
(3)there isn't a cold section in the system,
it's either warm or lava hot.. and I am trying to figure out why.. thanks for the help though..
I did
(1) how much Freon was in the system before you started? How much air? Moisture? The system only holds 17.5 ounces from vacuum. Anything more than 19 ounces is too much and will not cool but will feel warm/hot/lava through out. Lets say you only put 3/4 can in. That's 9oz. If the system was @ 10 oz it would feel ,,meh,, now add the 9 and it has too much to work at all .
(2) leads me to believe the system is overcharged
(3) another symptom of overcharging

My point is that until you absolutely know how much and what is in the system - you're shooting in the dark

I have found that my car cools best @ 15-16 ounces. 42* at the center vent in front of the garage & on the highway I turn it down. An expansion valve system will run with as little as 50% fill and still feel comfortable on the highway & ,,meh,, at lights.

S.
Edited by metroschultz, Jun 22 2018, 07:20 PM.
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Mrbreeze


Ok, thanks for the info, I'am going to see about working on it this weekend, I'll dig out the vacuum pump and do it the proper way.. thank you metroschultz..
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