95 E300 compressor worth an upgrade? - PeachParts Mercedes-Benz Forum

carl177 · #1 05-30-2016, 12:50 PM

Greetings all,

I am in the process of buying a new compressor, drier and an expansion valve for the 95 E300; I replaced the evaporator along with the usual suspects (drier and expansion valve) about three years back because it was leaking.

I noticed that MB has discontinued to carry the compressor new or in rebuilt form, so I have gone with a brand new Denso PA15 unit (In accordance with what the EPC calls for) with the connectors for the MB and all.

While searching for pricing etc, I also noticed that the E300 in 95 came with a Denso PA15, but the E320 seems to have come standard equipped with a PA17?

I am wondering if it would be worth returning and upgrading to the PA17 of the E320. Here is south Florida there is a lot of humidity and heat of course; my worries are that the PA17 would drag the car down on power and make it un-drivable. The E320 had somewhere north of 200HP from what I remember - where as the E300 was somewhere in the 125 - 130 range more or less.

Would it be a direct fit, or would I have to replace the hoses and the compressor bracket?

As always your kind advise would be greatly appreciated.



97 SL320 · #2 05-30-2016, 03:41 PM

Pulley ratio would also come into play here.

I don't know for sure, but I'd be willing to guess the E320 spins the compressor slower than the E300 at idle engine revs and needs more displacement to compensate. The E320 would have a higher red line than the E300 so the 320 must make sure the compressor isn't over speed.

You may be able to find dimensions on the Denso site. Unless the AC is deficient in capacity at idle due to low freon flow, I'd tend to install the recommended compressor.

If your high side pressures are high and low side low at idle, a larger compressor won't help since yo are already moving as much volume at the condenser / expansion valve can handle.

If the high side is low and low side high, more compressor volume would help as long as the pressures come in line if the engine is run to say 1500 RPM.

leathermang · #3 05-30-2016, 04:07 PM

The bottle neck on any AC system is air flow across the condensor...
So if you are wanting to upgrade...
make sure the condensor is clean,
as large as possible,
and has the best fans pushing and pulling air across its fins as you can afford.

KrustyKustom · #4 05-30-2016, 04:49 PM

Not sure about your 95 E300 but I can hang meat in mine on a hot day. I live in Houston and the AC in my 21 year old car continues to impress me. Even with out really recirculation it cranks!

How much are you finding compressors cost by the way?

Sent from my SM-G920V using Tapatalk

carl177 · #5 05-30-2016, 05:41 PM

First of all thanks everyone for their much appreciated input.

Compressors are going for about $280 to to $330usd. One has to make sure that they have the MB connector pins and their speed sensors. As I mentioned before MB does not supply them any longer, and as it turns out those compressors where widely used by Toyota automobiles as well.

My car cools down to 38's at the vents when moving but as son as you start slowing down the temps easily can climb up 70's at the vent. When standing it doesn't cool at all and the fan try's to adjust by kicking up more speed into the equation.

I have driven other 95's and their air conditioners are outstanding, much like you mentioned it is in your car in Texas; I also got a new fan clutch not much long ago and and cleaned out the bottom of the condenser which can get pretty dirty, those very last two helped out.

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leathermang · #6 05-30-2016, 05:49 PM

I think that is a clear indication of a problem of wind across the condensor... the forced air from going forward makes up for your lack of fans or bent fins or dirty fins, etc.. suggest you make sure condensor is up to snuff before spending money on compressor upgrades, etc... a compressor upgrade will not do anything for a system with a bottle neck at the condensor...the chances your compressor is not putting out enough ' product' ... is really slight given what it will do when in motion...

carl177 · #7 05-30-2016, 07:31 PM

Leathermang, perhaps a mildly clogged condenser? I mentioned this to Zulficar and he wisely advised me to check and clean the fins on the condenser - I did and took off the fans, cleaned out the bottom and in between of the condenser and radiator. Every so often I maintained those as well.

When I got the car about three years ago. The evaporator was leaking, I have always been afraid that the P/O may have put some type of sealant, could that have caused something like that and not show up when looked at with the pressure gauges?

My knowledge in A/C is not ample, but I have had two A/C people plug in gauges and they say that they look fine. The pods have checked out Ok - and I still have the issue of when hot there is a temperature fluctuation of 20 degrees more or less out the vents.

I have observed that when the car is stopped for a while - the hose that comes out of the expansion valve is barely cold and or sweating. On other w124's cars I have seen that same hose is frozen.

As always your advise is much appreciated.

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Jeremy5848 · #8 05-30-2016, 07:58 PM

I just completed replacing the leaky condenser on my '95 E300D; although (I thought) I was keeping the radiator and condenser clean, I was amazed at the amount of leaves, dirt, and miscellaneous debris I got out of the fins.

Jeremy

carl177 · #9 05-30-2016, 08:55 PM

Jeremey5848,

I wonder if I am doing enough to the maintain the condenser now; I spray some gentle all purpose cleaner/degreaser called "Optimum Power Clean All Purpose Cleaner Degreaser" I can shine a light and see through the fins.

Now I am surely wondering if I am doing all that I can to maintain it.

I will give it another clean and see if there anything else in there.

Jeremy where you experiencing
Issues when coming to a stop (with a good charge of course)?

I am attaching a link here to the product that I use to clean it.

http://www.autogeek.net/optimum-power-clean-apc.html

As always thank you all for the great advise.

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leathermang · #10 05-30-2016, 09:19 PM

Ok.. Carl, Make sure the fins are straight.... a thin set of pliers or a knife blade to move them to straight.. typically about 10-20 percent are bent due to various impacts over the years... and that needs to happen on the inside also...all a pain... and hard to reach.... but worth the effort...... . ALSO... the radiator needs to be clean and straight because if not that will act like a block behind your condensor...
If you need a chemically clean cleaner... you can go to a professional AC home parts store.. they will have two types.. two strengths or types of action.... one for interior fins for window air conditioners .... and a more caustic one for the outside fins of that same window air conditioner... usually in gallon containers and you dilute and spray it... usually the bubbling type....
While a large part of your problem is probably air across the condenser ...how are your fans ? Consider a high performance fan before more money on compressor..
Now for the FUN... have you cleaned your Evaporator fins inside the car ? check my signature ... remember... those inside fins are HALF the system with regards to you getting cool air....

97 SL320 · #11 05-30-2016, 11:09 PM

Quote:

Originally Posted by carl177

My car cools down to 38's at the vents when moving but as son as you start slowing down the temps easily can climb up 70's at the vent. When standing it doesn't cool at all and the fan try's to adjust by kicking up more speed into the equation.

There are a couple of other things that will cause poor cooling.

Expansion valve not opening enough.

Variable displacement compressor stuck at minimum displacement.

My 97 C280 had a volume problem and a replacement compressor solved that. Judging pressures on a variable displacement system are not the same as a fixed system. I forget the differences but seem to recall pressures stay stable making the system look fine.

You can also lift the hood and see if the engine driven fan is pulling enough air and the electric fans should turn on when system pressures rise high enough.

carl177 · #12 05-30-2016, 11:12 PM

Thank you both for the good advise and suggestions Leathermang and 97 SL320 - I am going to give it another thorough clean, and purchase one of those fin brushes I do recall seeing some bends but to my surprise not much to be honest. As far as the fans go they are both running good and strong.

Whenever I clean the condensor along with the radiator. After I am done putting everything away and all. I turn on the car with the A/C on. When the pressure build up (not too long here in Florida with all this heat and humidity) and the fans kick in I can hear and see at the bottom of the car a whooshing of water that has been resting in the condensor and the radiator fall on to the underbelly pans.

Please bear in mind my lack of knowledge on A/C systems. But do the 95's have a variable displacement systems as a 98?

Again all of this info is great as it is helping build a much better picture.

Much thanks to you all again. One can really feel at home in this forum with these great group of folks.

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Jeremy5848 · #13 05-30-2016, 11:46 PM

Quote:

Originally Posted by carl177

Jeremey5848,

I wonder if I am doing enough to the maintain the condenser now; I spray some gentle all purpose cleaner/degreaser called "Optimum Power Clean All Purpose Cleaner Degreaser" I can shine a light and see through the fins.

Now I am surely wondering if I am doing all that I can to maintain it.

I will give it another clean and see if there anything else in there.

Jeremy where you experiencing
Issues when coming to a stop (with a good charge of course)?



(1) I did not experience any significant issues (problems with insufficient cooling or otherwise) operating the a/c with the car not moving. No question, the a/c does not operate quite as well with only the fans pulling air past the condenser and radiator; an additional challenge is the heat of the pavement in stopped city traffic.

(2) The a/c in my '95 E300D operated perfectly for four years and then failed. The problem was a leak that had opened up at the bottom right (right side of the car) of the condenser. I took a chance and installed a junkyard condenser ($40) and a new receiver-dryer (MB dealer, $140). So far (10 days) it is working.

(3) For educational purposes I installed a pair of LEDs in the console; one illuminates when the compressor engages and the other when the aux fans go on in low-speed (as commanded by the pressure switch in the refrigerant line). From this I have learned two things: (a) unless it is extremely hot, the compressor cycles on and off. There is a temperature sensor in the evaporator (in the heater case); when it gets down to about 40°F, the compressor is turned off to prevent freeze-up. This is actually in the service manuals but not obvious to the casual reader. (b) if it is sufficiently warm, the aux fans go on even when the car is moving at highway speed. I did not realize this, since the fans can't be heard over engine and road noise when the car is moving. The aux fans stay on until pressure in the refrigerant line drops below the set point. Even if you switch to "economy" mode (compressor OFF) the fans still run, as long as the ignition and the climate control system are ON.

Here is a picture of the LEDs. The green one says the compressor is ON; the yellow one says the aux fans are ON in low-speed mode.

(4) I used a pressure-washer to clean the "new" condenser when I got it home from the junkyard. Worked like a charm. Careful! The high-pressure will take off paint (and skin, if you make the mistake of wearing sandals

). It's possible to do this cleaning with the condenser (and radiator) still in the car, if you've got a right-angle nozzle (spray from the inside of the engine bay forward through the radiator, opposite of normal airflow). The plastic shroud covering the fans also blocks part of the condenser and radiator but more importantly makes it hard to clean down there. Unfortunately, the only way to do a really good job is to take it all apart.

Jeremy

leathermang · #14 05-31-2016, 03:13 AM

Quote:

Originally Posted by carl177

.... and the fans kick in I can hear and see at the bottom of the car a whooshing of water that has been resting in the condensor and the radiator fall on to the underbelly pans.....

I only have general AC knowledge and FSM's for 123 Mercedes diesels....
So I have no idea about the difference between the 95 and 98.

There is something wrong with your system if you have condensation forming on your condenser.

Condensation should be forming INSIDE your evaporator inside your car... and drop it out of a tube under your car on a regular basis... and when you stop your car it will typically unload on the ground...

but the nature of the AC system... puts hot compressed vapor into the condensor top after exiting the compressor... and between the top and bottom changes into pressurized liquid refrigerant..... still warm... which should not cause any condensation to form... only when the phase change occurs at the Txvalve going into the evaporator with the inside air going across the fins is heat taken away from the does there exist a situation where condensation should occur. Perhaps you are using the wrong nomenclature ? or observing something not associated with the condensor/fans ?

carl177 · #15 05-31-2016, 10:05 AM

Leathermang, I just wanted to clear up that I was referring to the water on the condenser - to the times that I clean and wash it through and the car is turned on for that very first time after the wash. (I Assume that the pressure switch takes about 40 seconds or so depending on heat and humidity) and fires the fans off) then is when I hear and see the water gushing down.

Thanks again for all of your advice and ideas, I will be surely looking, and checking into all of these suggestions with the case that the car is presenting.

I currently have the car at my parents house. (very hot out here lately)