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  #1  
Old 02-09-2006, 04:39 PM
1989 560SEL, 1998 CL600
 
Join Date: Jan 2006
Location: Bay Area CA
Posts: 47
Replace Expansion Valve 'on principal'

1989 560SEL, 143000 miles

I need to replace the high-pressure hose of my A/C system (it has some cuts). The car has been without refrigerant for over a year now. I did not own the car when it lost the refrigerant. While I'm under the dash should a go ahead and replace the expansion valve anyway? I know that the valve is cheap but it looks like I'll have to buy some crowfoot wrenches for the task.

I'm undecided which way to go. Can anybody give me a convincing reason one way or the other?
~Dave

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  #2  
Old 02-09-2006, 05:34 PM
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Join Date: Jun 2004
Location: Baxter, TN
Posts: 88
expansion valve

I will vote for replacing the valve while you're already working on the system for a couple reasons. You don't know the history of the A/C unit, it may have an expansion problem that is unknow at this time and the big reason is it is easier now than it will be later after you gas the unit back up and perhaps find it isn't working correctly.
Good Luck
Al
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  #3  
Old 02-09-2006, 06:13 PM
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Join Date: Oct 2004
Location: Baton Rouge La
Posts: 2,630
I would do it and here's why..... it's cheap...and your refrigerant is already gone...so it's not like you have to evacuate the system..

by the way..it's likely the o-rings on the expansion valve will go before the valve itself.. unless someone tried to put sealer in the system...

my .02.

experience--- i almost didn't buy my CE because of an ac problem. it was the o-rings on the valve... but by the time you replace the o-rings..you are doing the valve anyway.

good luck... what's the valve -- 35 dollars?
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  #4  
Old 02-09-2006, 07:14 PM
Moneypit SEL's Avatar
Now what?
 
Join Date: Jun 2005
Location: SE PA
Posts: 525
Quote:
Originally Posted by al parker
I will vote for replacing the valve while you're already working on the system for a couple reasons. You don't know the history of the A/C unit, it may have an expansion problem that is unknow at this time and the big reason is it is easier now than it will be later after you gas the unit back up and perhaps find it isn't working correctly.
Good Luck
Al
You could make the same argument about any component in the HVAC. You don't know in advance whether anything else works or not, so why not change everything?

Personally, I'd not throw parts at it until I knew said parts were necessary.
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1989 300 SEL that mostly works, but needs TLC
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  #5  
Old 02-09-2006, 07:50 PM
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Join Date: May 2004
Posts: 108
The A/C expansion valve is very reliable in that car. I would not change it unless there is a known problem with it. What you do want to change is the reviever dryer. This componet is the part that keeps ice from plugging up the expansion valve. And after 1 year of exposure to the atmosphere through the cuts in the hose, it has lost its ability to absorb moisture & dirt from the system. One other componet that tends to wear out in that car would be the A/C suction line. I would grab part of the rubber hose near an end and try to rotate the hose. If you can rotate the rubber hose in comparison to the metel hose it is connected to it is wearing out and now is the time to replace. Best of luck. John
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  #6  
Old 02-09-2006, 08:30 PM
1989 560SEL, 1998 CL600
 
Join Date: Jan 2006
Location: Bay Area CA
Posts: 47
I've got a new receiver/dryer that I will install on the day I take the car to get refilled. Which hose is the suction hose? From compressor to condensor? All of my other hoses are in good shape. The high pressure hose got nicked when the left front fender got crushed in an accident. The event the led to the previous owner selling the car to a body shop and then to me.

The real challenge is going to be removing/installing the high pressure hose through the firewall. I'm hoping it is not as bad as it looks. I'm worried I'll have to remove the brake booster.

I'm still undecided about the expansion valve. Everyone's gone over the same arguments that I've debated. All valid points. Thanks.
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  #7  
Old 02-09-2006, 08:57 PM
LarryBible
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If it ain't broke, don't fix it. Unless you have confirmed that it is leaking at the bulb on the end of the valve which where they leak if they spring a leak, I would not touch it. You probably stand a bigger chance of introducing a leak by messing with the connections.

I would not replace it unless you have confirmed that there is a leak.

Good luck,
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  #8  
Old 02-09-2006, 08:59 PM
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Join Date: Jan 2006
Location: 90210
Posts: 25
Big hose =low pressure small hose = High pressure ,I would splice the hose in question as they make kits for that and then vac it down add some oil and charge it up then check for leaks. Then if you want to get pretty about it you can always go back and replace the hose .
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  #9  
Old 02-09-2006, 10:38 PM
1989 560SEL, 1998 CL600
 
Join Date: Jan 2006
Location: Bay Area CA
Posts: 47
The A/C shop I intend to use would not consider splicing the high pressure hose. Maybe someone else would do it but I trust this guy's judgement. I've already purchased a OEM fit replacement. I have no problem crawling under the dash to replace the hose. Just wondering how many curse words to save up for the job ()

I've decided to leave the expansion valve alone. I agree with Larry's comment. I stand just as much chance of messing up something else in the process. Since I have no prior knowledge about the condition of the system why pick that one compenent to replace? I'll replace the known defective high pressure hose, take it to the shop and see how it pans out.

Thanks everyone for your advice.
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  #10  
Old 02-10-2006, 10:02 AM
LarryBible
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I don't know what you mean when you say "splice" the hose. These hoses, or any a/c hoses from any car can be redone with new rubber hose at a hose or auto a/c shop and they will be as good as or better than new. It saves a BUNCH of money compared to buying entire replacement hose assemblies.

Good luck,
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  #11  
Old 02-14-2006, 11:59 PM
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Join Date: Jul 2003
Location: BC, Canada
Posts: 101
Expansion Valve replacement

If the car has been without refrigerant for a year wouldn't there be some risk of corrosion and therefore potentially some harm to the expansion valve and other components?

I'm interested in this because I have to replace the condenser and I was taking a similar approach- replace the condenser, receiver/dryer, expansion valve, O-rings and Schrader valve seals, and then recharge with R-12. It appeared practical to replace all the small cost items that can end up creating further costs if not dealt with in one job (excepting the evaporator which, of course, is another job in itself).

Thanks for your comments!
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  #12  
Old 02-15-2006, 10:18 AM
LarryBible
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A system can be "empty" for quite some time without having corrosion problems. Just because it is empty, does not mean that it is OPEN. Typically a system that is considered empty is more correctly LOW on refrigerant. As long as there is even one pound of pressure in the system, then it is not getting any atmospheric air inside, thus it is not being contaminated.

Now a system that is OPEN is another matter. In the case of a system that has had a line disconnected or some such for a period of time, it probably should be flushed component by component, r/d replaced and then proper evacuation before charging.

Hope this helps,
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  #13  
Old 02-17-2006, 08:58 AM
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Join Date: Feb 2006
Posts: 12
I would replace the hose, valve, dryer and convert it R134a freon. That will save you some headacks later on.
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  #14  
Old 02-17-2006, 10:13 AM
LarryBible
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I don't necessarily disagree with BenzDoc about changing the parts although I'm not one to change good parts. I do, however, strongly disagree when it comes to converting to 134.

R12 prices are coming down rapidly while 134 prices are increasing at about the same rate. It may very well be that R12 prices fall below 134 prices this year due to rapidly declining R12 demand.

It will cost you more to do a proper 134 conversion than the difference in the two refrigerants and your system will lose about 15% of its cooling capacity. Additionally it is proven that statistically, systems converted to 134 experience failure within two years.

Good luck,
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  #15  
Old 02-17-2006, 02:51 PM
1989 560SEL, 1998 CL600
 
Join Date: Jan 2006
Location: Bay Area CA
Posts: 47
I've been told that to do a proper conversion to R134a requires a switch of the condenser. The R134a condenser has twice as many loops as a R12 condenser.

I got a very reasonable quote to refill my system with R12 ($270). And I live in California!

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