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2003 Escalade EXT AC recharge

half-breed

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Feb 14, 2002
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Chicago (Woodstock) area
I went to charge my son's 2003 EXT and the two hoses with the caps look identical (bight not be). How do I tell which one is the low pressure line that I need to add Freon to? I did a search on this forum but could not find anything.

Thanks.
 
LP port is usually nearer the firewall by the LP pressure switch.
USually on the larger OD line.

They are different I thought?
 
Take a look here...


https://www.youtube.com/watch?v=dIh4Cgql5r8


https://www.youtube.com/watch?v=0j3d8C4CpC4
 
Here is a picture of the AC lines. Which black cap is the highside, which the low side? I did not expect both of these caps on what I would think is the low side line....


20160903_175144_zpsdgeqyeyw.jpg
 
Are the caps by chance labeled?  I charged our Zuk earlier this summer the the caps were marked with "H" and an "L".
 
My GUESS is the one closet to firewall and evaporator would be low pressure.
THere are no others?

I think inside the connector joining the 2 lines is your expanion valve AKA Orifice tube where it changes from High to low pressure.

TO confirm if it runs at all, the colder one will be Low Pressure.
 
Look to see if there are any other caps on the lines going to compressor; the smaller line of the two as that would be high pressure.

Small line is high pressure
Large lines low pressure.

Put your gage hook up on the one closet to firewall and turn it on and watch pressure gage.
My simple recharge kit has a gage to tell you when full.

If it climbs above the normal range when on than you found the high pressure one.

If it stays below the normal range when on then you found the low pressure and can start adding and watch gage.

With it off they would read the same after a few seconds.
 
Does the a/c blow plenty cold at driving speed, but at idle, sitting in traffic or when you are checking the coldness of the lines with the hood up sitting in the driveway, is the a/c blowing much warmer air and it hard to feel a difference in the a/c lines?

My EXT had a well worn out engine fan clutch when I got it and the a/c performance was marginal at idle and in stop and go traffic.

I replaced the fan clutch and ever since my a/c has been frosty cold on the hottest days, even at idle and in traffic.

If the current fan clutch can easily be spun with the engine off and you DO NOT hear any fan roar at start up each morning, I would replace that fan clutch before I started messing around with the refrigerant.

Just a small amount too much refrigerant will make the a/c perform WAY worse.

Chances are, if that fan clutch has not been changed in many years, it is due anyways.

No harm done in getting that part freshened up, regardless.

When the a/c is working correctly, there will be an obvious difference in the coldness of the a/c lines.

The cold line is your low pressure side.

I stepped outside just now and took my infrared thermometer to check the line temps.

This morning, it is 75 degrees outside with high humidity.

With my truck running at idle with the hood up, the line coming out of the accumulator and going into the firewall was at 60.2 degrees and sweating.

The temp of the evaporator line at the service port closest to the accumulator was 83.7 degrees and sweating.

The service port on that same line, further toward the front of the truck, had a temp of 107.6 degrees and was dry.

Much warmer.

I then closed the hood and sat in the closed cab with the a/c set to auto and the temp set to 66 degrees.

After letting the truck run with the a/c running for 5 minutes at idle and the auto a/c fans had slowed to a low speed, the temp of the inside of the center vent was 40.3 degrees.

Perhaps that will give you a baseline.
 
The AC is weak at idle as well as driving. From under the hood I can't see any other lines with caps. I did not look from under the car. It is hard to see the compressor from under the hood.
 
I looked through the diagrams in the 2003 Service Manual in the HVAC section and the two ports you are seeing appear to be the only two service ports on the system.

Both of those ports are located on what is called the evaporator tube.

Both service ports also appear to be different sizes, so a refrigerant refill can set will most likely only fit on one of those ports.

The service port closest to the accumulator (that can-like device near the fire wall) is most likely the service port you are looking for and is most likely the port that will take the refill can line.

Inside that evaporator tube at the location between the two service ports, is a device called an "Expansion (Orifice) Tube".

This is one of the reasons you can feel a difference in temperature between those two areas of the evaporator tube.

It is not just a straight through tube connected at that joint.

This device is located inside the forward most part of the evaporator tube at the junction of the evaporator tube between the two service ports.

You should see high pressure on one side of that device and lower pressure on the other side.

Even farther down the evaporator tube, toward the truck frame and closer to the front of the truck, is the A/C refrigerant filter.

It is a device located between two sections of the evaporator tube.

Not that any of these devices might be a problem, but anytime you have a connection joint in a refrigerant line, that is a possible location of a refrigerant leak.

As you probably already know, a healthy A/C system can easily hold a good charge for the life of a vehicle.

My 1993 Ford Explorer still has it's original Freon charge from the factory, some twenty three years ago.

If your A/C system is really low on refrigerant, you have a leak somewhere that will never go away and needs to be found and fixed.

Adding an odd can of refrigerant now and again will never allow you to achieve the correct level and get the proper performance of the system.

Getting it fixed correctly will end this hassle and will protect your system from more costly repairs down the line.

But that's just how I prefer to handle these types of things.

Hope you find a solution that works for you soon.

(y)
 
Hey I was right above in my post.

One nearest firewall is your LP port.
the fitting hides the ORifice Tube.

the port closest to truck front is HP.
 
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