Expansion Valve A/C

[shamaal]

I don't believe that expansion Valve A/C are used on Explorers, not my in my Mazda Navajo at any rate. I've added it to this forum though because of a mistake I made in another thread. Having serviced EV systems in the Navy and Air Force there are some terms and assumptions that I carried into a discussion on an the Ford orifice system that unecessarily confused a participant.
I won't describe the system principles of operation but I'd like to point out the differences
1. The orifice system uses an accumulator, the EV system uses a receiver drier. These are somewhat similar in purpose and the terms are often used interchangeably.
2. The accumulator on an orifice system is on the low pressure side. In the EV system the receiver/drier is on the high pressure side. These are NOT interchangeable. It is common practice on an EV system to pour the refrigerant into the Receiver/Drier. It is NOT recommended to pour liquid refrigerant into the accumulator.
3. The orifice system uses an ... orifice, the expansion valve system uses an .... expansion valve. Again the terms are used interchangeably - the expansion valve system contains a few more components and is more versatile.

Generally speaking cross referencing terms is no harm, we generally know what people mean. But if anyone wonders why different terms are sometimes used, hopefully this reduces the confusion.

 

[Glacier991]

I too have been guilty of tending to use expansion valve and orifice interchangeably. FORD uses the Orifice system. GM and others tend to use the expansion valve system, though not exclusively.

 

[shamaal]

Actually what inspired this particular post on expansion valves was an earlier thread in which I misidentified a component. I didn't think it through - for an expansion system I was right for an orifice system I was dead wrong. Luckily it was impossible to use my posting because the physical connectors wouldn't allow it, but still it's bad information with potentially serious consequences. An earlier post about about orifice tube location mistakenly places it between the accumulator and the condensor - correct for an expansion system but not for an orifice system. On the Mazda/Ford it's between the condensor and the evaporator.
Most people here don't care particularly about what it's called - thingie, whatcha-ma-callit, doo-haber-dingie - as long as they can find it, perhaps understand it and gain confidence they can fix it.
Poop - now I'm pontificating - not my intention.

 

[uabegr]

Get this - On my '02 Explorer XLT with rear air

an orifice tube is the metering device for the front evaporator and an expansion valve is located in the rear to serve the rear evaporator.

That one stumped me but, in my attempt to completely replace the A/C system, I found this out the hard way.

 

[shamaal]

I heard there were dual type systems on the newer vehicles, but was unsure of the details. Are the two systems completely separate? The rear has an expansion valve; is there a line with a bulb at the end going from the EV to the evaporator?

I would be curious why Ford would mix the systems. On an orifice system the accumulator is on the LP side, while on an EV system the receiver is on the HP side, why uneccessarily complicate this?

Thank you for the info, I'll file it away for future problems.

 

[Glacier991]

The orifice system has advantages and disadvantages. An expansion valve system provides more control temp wise without mixing... the orifice valve sysptem depends on mixing heat to adjust temps. In a dual zone system the idea of one of them being controllable by an expansion valve with the other blended by heat makes perfect sense to me.

All said, I think expansion valve systems are better...but they all work, so what the hell.

 

[shamaal]

I agree with your statement about expansion valve systems being better, they most certainly provide more efficient cooling. What I find puzzling, is why use two different sytems? Why not both orifice or both EV?
My experience is that the more variety you have in common parts, the more your manufacturing costs increase due to inventory, installation tooling, drawings, tech training, etc.
I'm sure they had their reasons.

 

[ma96782]

Maybe it's a FORD vs. CHEVY thing.

FORD's BETTER IDEA??

or

CHEVY's AMERICAN REVOLUTION??

OK......I'm just joking........I'm a, "What you ma call it," kind of guy.

Aloha, Mark

PS.............or, "Who's patent were gonna use and how much will it cost?"

 

[Glacier991]

Here is my guess. In a dual zone system it might be more expensive engineering wise to have the rear seat passengers blend heat for cooling adjustments than going the expansion valve route. There could also have been enginering reasons why a 2nd orifice tube might have been problematic far back in the system, I dont know.

 

[shamaal]

The other possibility is that as a supplemental unit it may be less robust. Using an expansion valve provides cooling across a broader range of conditions.

 

[Glacier991]

Good point. As usual.