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With Summer coming finally full swing, a lot of you want your A/C blowing COLD in our cars.

Well, mine hasn't worked since last fall and I set out to fix it yesterday. I tracked the leak (with a leak detector) down to the high pressure port (the one near the front with the red cap).

I went to Napa and bought a new one (THESE CANNOT BE LOOKED UP BY APPLICATION - YOU HAVE TO GET SOMEONE WHO KNOWS WHAT THESE ARE).

The Napa part number is 409521 and is listed as AC SERVICE PORT VALVE (about $4.00).

Anyways, I replaced the port, recharged the system, and it works GREAT!


Now my A/C was blowing cold, but like other cars I've owned in the past, it works better moving. I figured it's because the air is moving through the condenser better when driving.

Well, I was looking at the system working under the hood and a light bulb went off in my head that I think all you that live in hot climates will love to hear - a mod that costed me $1.29 in parts and actually worked!

An A/C system works be compressing freon to liquid where it is pumped to an expansion valve (orifice tube) and expands into a gas (where it gets very cold). Usually this happens right before or even in the evaporator core located in your passenger compartment.

What I found strange in our cars is the orifice tube is by the condenser and the small tube that runs from the front of the car to the evaporator core is always VERY COLD and sweats like crazy if your system is working good.

I got to thinking, that system is absorbing a TON of heat from under the hood here before it even GETS to our passenger compartment; WHAT A WASTE!

Here is the idea. I bought a section of 1/2" insulating tube from my local hardware store at a whopping $1.29 - looks like this:


I wrapped that cold tube up with the insulation from the orifice tube to the passenger compartment. It looks like this when finished:




Some of you are probably thinking (as I did) if this really is gonna make much of a difference. Well, here was my experience:

It was 88-90* F here yesterday and I could get the inside of the car to about 68-70* F and that was MAX A/C. After I did this simple mod, I was able to get the interior of the car down to 66-67* F and it doesn't heat up so much when sitting still like it used to.

Hey, for a buck, I suggest y'all try it and report back with your own experiences!
 

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You can also help by insulating everything else that gets cold; the accumulator and return lines to the compressor as well. The less heat you absorb in the engine bay, the more heat you can absorb from the cabin. Your condenser can only remove so much heat from compressed refrigerant.
 

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Discussion Starter #3
You can also help by insulating everything else that gets cold; the accumulator and return lines to the compressor as well. The less heat you absorb in the engine bay, the more heat you can absorb from the cabin. Your condenser can only remove so much heat from compressed refrigerant.
Well, if your system is working well, the return tube (the big one) should be warm, not cold because of the heat it absorbed from your passenger compartment (at least on a hot day it should be warm).

I don't know if I would want to insulate the hot tube...

But you may be right, Brandon. I've never tried it... :zdunno:

The kicker that gets me is why isn't that orifice tube near the evaporator like 99% of the a/c systems on the planet? I'm sure Ford had a reason - I just don't know what it is.
 

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Don't insulate the hot side. When the refrigerant is hot/compressed, the more heat you remove there, the more heat you can absorb on the cold/low side.

The amount of heat you take out of the hot side is theoretically (in a perfectly efficient system) equal to the amount of heat the low side can absorb. No system is perfect, but getting as much heat out of the hot side as possible means you can get as much heat into the cold side as possible. The more heat you put into the cold side, the more heat you have to take out of the hot side.

Since the condenser/fans can only remove so much heat from the hot side, to be able to get more heat out of the cabin section of the low side, you have to restrict the amount of heat going into the cold side outside the cabin. This includes both pre and post evaporator.

Just remember, the amount of heat you absorb on the cold side HAS to come out on the hot side. It doesn't matter whether it entered before the cabin or after the cabin.
 

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Discussion Starter #5
Don't insulate the hot side. When the refrigerant is hot/compressed, the more heat you remove there, the more heat you can absorb on the cold/low side.

The amount of heat you take out of the hot side is theoretically (in a perfectly efficient system) equal to the amount of heat the low side can absorb. No system is perfect, but getting as much heat out of the hot side as possible means you can get as much heat into the cold side as possible. The more heat you put into the cold side, the more heat you have to take out of the hot side.

Since the condenser/fans can only remove so much heat from the hot side, to be able to get more heat out of the cabin section of the low side, you have to restrict the amount of heat going into the cold side outside the cabin. This includes both pre and post evaporator.

Just remember, the amount of heat you absorb on the cold side HAS to come out on the hot side. It doesn't matter whether it entered before the cabin or after the cabin.
Which is exactly my point - why build a system that is going to absorb heat from outside the cabin? Why is the expansion occurring so far from the evaporator on the hot side of the system? Just a dumb design, imho.
 

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I've thought of that too... :zdunno:
 

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So was it the part i pointed out that was possibly bad?
 

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Discussion Starter #9
So was it the part i pointed out that was possibly bad?
I don't remember you pointing out anything! lol

But I had been checking the pressures and touched that valve right before it quit working! :eek:

So, I probably caused the problem - at least I fixed it...

Way too cluttered looking for a measly 2* and 88-90* is window down weather! :tongue:
Adding insulation to one tube is cluttering? :confused:
And I would think you from Northern Illinois would HATE 90* weather! :rofl:
Does it even get 90* there?
 

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Illinois? Nah. But here in Ohio we get to see triple digits and dew points in the 70s on occasion...
 

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Discussion Starter #13
It hit 90* here 3/4 days out of the last week, I wouldn't think of using A/C when it's that nice out. It dropped down to 52* today and I'm freezing my ass off :mad: I only use A/C in triple digits.

And yes cluttered, the stock lines alone are too cluttered! lol
Wow, you sound like a Floridian! :tongue:
 

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No such thing as Cold air .. just air with less heat in it. ;)
You mean less entropy. :)



The reason the expansion valve is not close to the evaporator is the way it's built; the airbox is so crammed in that a 'simple' heater core swap is a nightmare. :)

Imagine doing the evaporator. :facepalm:

To fix a wasted system on our cars, all the stuff you have to replace is up front and reasonably accessible.
 

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80-90 is window down weather here in CA... Beside this week its been 95-103. Yipppy cant wait until june, july and aug. Probaly going to be like last year 100-117 everyday
 

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If moving, 80-90 is window down. When stopped in traffic, when the relative humidity is in the 80's or 90's ...

I worship the ground that the inventors of Freon(tm) walk on! :diablo:


(Yah, I'm a wimp. Bite me.)
 

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Discussion Starter #17
If moving, 80-90 is window down. When stopped in traffic, when the relative humidity is in the 80's or 90's ...

I worship the ground that the inventors of Freon(tm) walk on! :diablo:


(Yah, I'm a wimp. Bite me.)
Yes, it's the humidity that sucks; I lived in Phoenix for awhile where the humidity was so low, 90s felt like 70s! My car didn't have working a/c when I was out there and I remember one particular day when it was 124*F outside and the radio kept warning people to not stay out in it more than 10-15 minutes.
 
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