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  #46 (permalink)  
Old 06-26-2020, 08:37 PM
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Latech that is where I fail, I would have to take it in, no scanner for me. I did check the leads coming to high pressure switch everything is reading correct, but I have no way to check the sensor its self.

The weird part is the sensor kicks out at 428 psi (supposed to), well this problem would shut down when I was a little over charged and had other condenser, it would hit high psi of about 300 max, system would shut down.

Now with correct charge and new condenser it hits 225 and still shuts down. Low pressure has always been 25 to 40 range.

Still puzzled not saying your wrong just no rhyme or reason with this problem, it is defiantly something turning it off and no idea why my car temps are so high

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  #47 (permalink)  
Old 06-27-2020, 07:10 AM
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Sounds like the pressure switch is failing.
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  #48 (permalink)  
Old 06-27-2020, 08:52 AM
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Jump B+ to it and watch your gauges. Be ready to pull the plug if the high side goes up. See how it does.
This bypasses the rest of the system, so you can at least see how your new posts work.
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  #49 (permalink)  
Old 06-27-2020, 09:24 AM
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Best not ot "Jump" anything without knowing the cicruit operation.

The pressure sensor is hooked solely to the PCM and does not use 12 volts. Hooking 12 volts to it would likely fry it.
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Old 06-27-2020, 12:27 PM
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Life certainly was less confusing before microprocessors ,pressure switches that were on/ off & onboard computers.
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  #51 (permalink)  
Old 06-30-2020, 03:16 PM
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As for the compressor clutch cycling, I ran across this...in a General Motors "ECM tips"....

"Engine coolant temperature sensor (ECT) and,ECM air conditioner compressor control. If the coolant temperature rises to a predetermined level, the ECM will disengage the compressor clutch.Jun 18, 2019"

As for your readings, (I think you might have a few switched) in my 50 years of pretty much all phases of HVAC systems, I've never seen such weird symptoms. Are you saying that you have NO piping that is cold?.. Did you say you can't reach/touch/see the TXV on both entering and leaving side? .. the leaving side should be COOOLD.. by anybody's measure..

Here is what you should be feeling on the lines (with your hands, not the laser gun)..
Compressor discharge toward condenser ...HOT AS HELL
from condenser to receiver.... DAMN HOT, but not as hot as hell...
Receiver and line leaving the receiver and entering TXV.. Same as condenser to receiver..
LEaving TXV... DANG COLD
leaving evaporator - suction line... Still pretty dang cold, but not as cold as leaving TXV..

Nearly sounds as if you are not getting a pressure drop through the TXV if I'm reading your temps correctly...

The fact that you have about 180 psi difference in pressures SHOULD produce COLD parts of the sytem, but then your supply air temp is crazy (too high)...

Do you have damper doors/operators confirmed that the ECM or some other thing hasn't failed, causing the damper operator to bypass the evaporator and throw the air through the heater?...

You don't have a dirty condenser, and you don''t have a dirty evaporator... there is ONE thing that is SCREWED on your system.. we just gotta figure out which part... but right now, I'm at a loss too... keep us posted..
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Old 07-03-2020, 06:18 PM
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Ok so here's a little update, after reading 49 coupes latest post, I got a chance to run the car again, to double check my notes and check points.

I want to say it is very hot here right now 90's (if this is making a difference?) anyways I started the car and run system, what has changed ???? but temp wise the system is working correct much like the other sky I got my notes from, in fact txv was sweating and cold and the system was blowing 55 deg out the vents.

BUT it is still shutting down and takes 10 minutes until it will cycle again, the parent problem, I think I have figured it out, temp sensor in dash.
This is based on the time it takes to start cycling again, a few days ago when running the system to gather facts, I timed it and it took 20 minutes, this was on a cool day 78 deg or so. Now when I ran it yesterday and it would shut down it would cycle again in about 10 minutes, temp outside 90 degs or so.

I am thinking the warmer temps are warming this sensor up faster or resting it quicker do to higher air temp. Sensor is on order will let you know once I figure out to get to it.

Have any of you ever pulled the dash on a Saturn sky?? that's going to be the hard part

I think over all this system had 2 problems, but I only noticed one because the second one was masked by the parent problem system shutting down.

Problem 1) the dash sensor, 2) A condenser externally plugged solid (hidden because of cycle problem.

I have attached to 2 pdfs one of yesterdays temp finding and one of where the dash sensor is.

I also want to say it looks like Buzz LOL had it in his post#11 and 49 coupe back in post#23.

Thanks guys, I will let you know how things go once i find out how to change sensor.
Attached Files
File Type: pdf AC.pdf (224.2 KB, 4 views)
File Type: pdf sky dash.pdf (951.5 KB, 3 views)
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  #53 (permalink)  
Old 07-03-2020, 07:46 PM
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This ,like I said, is where a GOOD scanner comes in to play and shines.

Checking BCM data would reveal the temp sensor was an issue.

The HVAC control module monitors the temperature of the air passing through the evaporator by the A/C evaporator air temperature sensor. This sensor is located on the evaporator core. The temperature is used to cycle the A/C compressor ON and OFF to prevent the evaporator core from freezing. A thermistor inside the sensor varies its resistance to monitor the evaporator air temperature. The HVAC control module monitors the voltage drop across the thermistor when supplied with a 5 volt reference signal.The evaporator temperature sensor will not allow an A/C request to the body control module (BCM) at temperatures less than 0C (32F).

The sensor value is easily available to read on a scan tool.Scan live data BCM.

I am glad you are finally getting it Ironed out.
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Old 07-03-2020, 09:46 PM
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Yeah my stubbornness and not trusting dealerships, sometimes gets in the way, its not the mechanics at dealers its the service write up people and management pushing sales/commissions.

Last time I took car in for a random miss fire, (it was moving around), never really did find problem, anyways, took it in and told the write up tech the problem and how and when it happens etc, what along with somethings I had already changed, like plugs and plug wires etc.

I get a call from dealer and list of bad parts, some of what I already installed new, the biggest kicker is they said the turbo itself was bad. I go to pick up car and pay them their 100 dollar inspection fee, but I get to talk with the tech. I tell/ask him about the turbo and looks at me dumb founded, he say the turbo is fine and has no idea why service girl listed that as bad or a problem. Tech said he could see misfire and feel it on road test, but had no idea what was causing it.

Dealer was willing to chase problem for 100 an hour, hell I took it to another shop to find problem they could not find it either and they cost me 700.
Once I got my new house and garage, I pulled injectors last item to be tested and checked, everything tested good, reinstalled injectors no more miss fire. I really don't know what miss fire problem was but it is gone.

Anyways a little off track, but that's why I don't like or go to dealers. Where I used to live, I had a great A/C shop I would do business with and would have drove the car to him in a heart beat, but he retired and closed up shop.
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  #55 (permalink)  
Old 07-04-2020, 03:37 AM
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Quote:
Originally Posted by 95 Truck View Post
I also want to say it looks like Buzz LOL had it in his post#11
Thanks for the credit... I was feeling bad for you purging the system, replacing parts, recharging it again over and over... glad you're getting it narrowed down... now I just have to figure out why my home A/C quit today, July 4th, with temps in the 90's around here... and nights mostly only getting down in 70's... Weird thing is when the central air was first installed about 30 years ago it also quit on the 4th of July !!! ... But that 4th of July was 105 degrees! Didn't bother me much though since I spent the day out on the boat and in the water on Lake Erie. Turns out back then the furnace / A/C installers had left several tiny leaks in tubing solder joints and the charging ports were also leaking so soldered them over solid as well... and this is the first problem since then... hope it's only a fuse or something else cheap and simple... I'll check on it later when it gets daylight... Well, I did check to make sure the outdoor condenser hadn't been stolen, never know these days...
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Old 07-04-2020, 05:46 AM
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Buzz take a good look at the capacitor and the contacts, it is very common for the capacitor to give up. When it goes bad you will here a humming outside at the unit, like it wants to start, Also the contacts that capacitor supplies can burn out, might need to drop power and remove these to get a good look at them.


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  #57 (permalink)  
Old 07-04-2020, 06:12 AM
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Thanks for the tips... after 30 years, could be about anything... maybe an exploded capacitor... those are easy to spot... LOL!

Thought my refrigerator from the 1970's went out the other day... turned out the Green Machine energy saver box it was plugged into had failed... I saw a test that claimed they worked, so I had bought one long ago, but tests lately have shown similar products actually increase energy usage... that old test may have been a marketing fake one... Once I plugged it in direct, I noticed the refrigerator and freezer are staying much colder now... my ice cream had been staying almost runny lately... and was concerned my meats weren't frozen solid enough...
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  #58 (permalink)  
Old 07-04-2020, 11:22 AM
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Quote:
Originally Posted by 95 Truck View Post
Yeah my stubbornness and not trusting dealerships, sometimes gets in the way, its not the mechanics at dealers its the service write up people and management pushing sales/commissions.
Believe me, I completely understand. I avoid Stealerships at all costs.
I never liked working for them. I always liked Independent shops the best.

The stealerships dont care. They use the service department to help keep the doors open for the pretty boys to sell cars.

Kind of an imbalance of reward. They do the easy stuff , and we do the tough stuff. They make the money, we make the "wage" cough cough .
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Old 07-04-2020, 11:23 AM
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Quote:
Originally Posted by LATECH View Post
Believe me, I completely understand. I avoid Stealerships at all costs.
I never liked working for them. I always liked Independent shops the best.

The stealerships dont care. They use the service department to help keep the doors open for the pretty boys to sell cars.

Kind of an imbalance of reward. They do the easy stuff , and we do the tough stuff. They make the money, we make the "wage" cough cough .
And Kudos for BUZZLOL for the accurate mention of the temp sensor in the evap. Good lookin out.
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