95 E300 compressor worth an upgrade? - Page 3 - PeachParts Mercedes-Benz Forum

carl177 · #1 06-01-2016, 09:22 PM

Quote:

Originally Posted by Zulfiqar

Also make sure your heater valve is not malfunctioning - if it lets hot coolant into the core, your A/C would be warm performance.

Zulfi - I thought about this a while back and about two years ago I took the valve down clean it and changed out the seals (because they were a bit flat) The thing is that on the other side of the spectrum when driving I get 38 degrees out the vents (I assume that it is because the compressor its pumping more) At the time I went ahead and did it anyways just to make sure that it was all working correctly.

When driving the A/C cools well, and As soon as I come to a stop almost immediately the temperature starts rising (I see it on a vent gauge that I carry around) and double check it with an infrared thermometer.

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leathermang · #2 06-01-2016, 09:34 PM

Quote:

Originally Posted by carl177

.... (I assume that it is because the compressor its pumping more) ....

But that is ignoring two potentially important facts....
One is that you have changed the variable which is the bottleneck of all AC systems... air across the condensor....by removing the Forced Air of the car moving forward.....
That the cooling load on the car is more when driving fast.... leaks and wind hot air across the glass.....
Your gauges check... if you do it correctly should tell a lot about the situation....

Zulfiqar · #3 06-02-2016, 12:03 PM

Quote:

Originally Posted by carl177

Zulfi - I thought about this a while back and about two years ago I took the valve down clean it and changed out the seals (because they were a bit flat) The thing is that on the other side of the spectrum when driving I get 38 degrees out the vents (I assume that it is because the compressor its pumping more) At the time I went ahead and did it anyways just to make sure that it was all working correctly.

When driving the A/C cools well, and As soon as I come to a stop almost immediately the temperature starts rising (I see it on a vent gauge that I carry around) and double check it with an infrared thermometer.

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Now this data is pretty important, its showing either low quantity of refrigerant or a malfunctioning expansion valve.

There was one car I was trying to rectify - it was a nissan and had this same behaviour, after dealing with almost all dead ends I looked at the fans - they were spinning at slow speed (correctly for low load) but I could actually stop them with my hands (weak motors)

replaced the set with a replacement one and all was well again

carl177 · #4 05-31-2016, 08:24 PM

97 SL320 - thank you for the information on the compressor I can understand now a bit better when you mentioned that your 97 C280 had a volume problem with the old compressor.

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carl177 · #5 05-31-2016, 08:30 PM

Jeremey5848, that is a pretty clever thing that you did there with the lights. For some reason I always figured that once you get the car going the auxiliary electric fans would just shot off because of the ram air effect and not just keep on going at those speeds. (One surely learns something everyday)

Again I want to take the opportunity to thank you all for the information, ideas and advice.
There is a great wealth of knowledge and that along with good folks that are willing to share it is simply priceless.

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carl177 · #6 05-31-2016, 08:37 PM

In the next couple of days I am going to put the car in the shop for a little body work courtesy of the P/O that has been bothering me for a while. This will unfortunately leave me with limited access to the car.

But I will try to get a hold of a set of gauges, and get pressure readings to post those here along with the ambient temperatures to hear what your thoughts are.

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leathermang · #7 05-31-2016, 10:09 PM

For a good test you need a really good squirrel cage blower right at the grill....on high...
Windows open, blower on low, thermometer in center vent, high idle....

Zulfiqar · #8 06-01-2016, 12:03 PM

I was wondering, is the climate control unit seeing correct cabin temperature? - might try cleaning the sensor with a duster can.

leathermang · #9 06-01-2016, 12:17 PM

Quote:

Originally Posted by Zulfiqar

I was wondering, is the climate control unit seeing correct cabin temperature? - might try cleaning the sensor with a duster can.

WARNING.... those ' dust cans' typically from an electronics store...which I made the mistake of assuming was packaged air....( just needed inside photo slide dust removal ) ....
MAY be a refrigerant and FREEZE what you shoot it at... mine also had a faulty trigger...and one should wear gloves when trying one of these cans... mine sprayed this cold stuff on my finger....

Zulfiqar · #10 06-03-2016, 11:50 AM

Quote:

Originally Posted by leathermang

WARNING.... those ' dust cans' typically from an electronics store...which I made the mistake of assuming was packaged air....( just needed inside photo slide dust removal ) ....
MAY be a refrigerant and FREEZE what you shoot it at... mine also had a faulty trigger...and one should wear gloves when trying one of these cans... mine sprayed this cold stuff on my finger....

no sir - they are not air, its a refrigerant in there and its very important to never shake the can and never use it tilted or sideways and never in long bursts. It can cause you harm.

carl177 · #11 06-01-2016, 09:13 PM

Quote:

Originally Posted by Zulfiqar

I was wondering, is the climate control unit seeing correct cabin temperature? - might try cleaning the sensor with a duster can.

Zulfi - about a year ago I did the paper test in the top grill to make sure that it was working properly and it held up the little square, around the same time I also brought down the airbag and cleaned out the sensor to make sure that it was sending the right information back to the unit.

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carl177 · #12 06-02-2016, 08:56 AM

Very very True Leathermang; I am working on setting sometime and to get some gauge readings posted.

More or less what are the correct readings? In other words where should one be as far as reading go - I have looked the at a few A/C threads but I am not sure if those would apply to all cars.

As always thank you for the kind advise.

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leathermang · #13 06-03-2016, 11:08 AM

Yes, has a ' set ability ' and is then only variable according to the rpm it is being rotated at.
Since your indicators involve a change in the forced air through the condensor... AND this is something the AC MB manual stresses in an AC test .. ( the lack of proper test air was why the MB AC manual warned , then finally eliminated, the inline sight glass for checking the refrigerant ) it was possible to have air bubbles showing even with a full charge... but not sufficient air from a fan for proper testing...
Pictures of a roll up centrifugal fan positioned right at the grill at a MB dealership indicate how important this item is...
So I hesitate to name numbers...but there are lots in the AC threads ... you do not want too low or too high and the main thing is to have a ' spread' because that is what your whole system works on....

carl177 · #14 06-28-2016, 08:27 PM

Ok friends, I got a neighbor that has a general mechanic shop to put up the gauges for the car about a month back or so.

He told that the low pressure was too high, 80 to be exact.

After reading about pressures on the forum. I went ahead and replaced the compressor, expansion valve and of course the dryer. refilled at 2.2 as the green label on the car states. (The machine that they use does the whole process vacuum and charge with the car off in one shot)

I took it to Mercedes Benz and they replaced what was mentioned above on my request. Today after the work was done. We put the gauges again and we get 45PSI on the low and about 280PSI on the high. While standing rose to 350PSI quite quickly when revving the car to about 1800 to 2300 RPM's, the low pressure went down to 35PSI, both electric fans were on (It was 84 degrees outside about 70% humidity and out the vents the lower we got was 58 degrees)

I am under the impression that the high pressure seems a tad too high perhaps, not sure if under that scenario (outside temperature, humidity, car under the sun)

Looking for advise at his point from our fellow members.

As always thanks in advance.

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carl177 · #15 06-30-2016, 04:11 PM

Would it be correct to say that the two electric fans in front of the condenser come on at one speed - and only go to the second speed it the engine temperature goes over the 100 degree mark, or should they kick over to the second speed anytime before that?

Currently they both turn on and are very hard to stop by hand (thinking that they still seem strong)

As always your input is greatly appreciated.