I have a few problems with the climate control on my 85300TD. I hope with a few sugestions I can repair them myself. The first problems is the air compressor. Is it easy for a total idiot to replace, and if so what exactly will I need? I keep reading about "If you're going to do it the right way..." you need to replace the receiver-dryer. Is that true? and where is it located on a 1985 300 TD Turbo. My goal is to replace the compressor myself and have someone else convert the system over. I took my car down to a recomened shop and they told me that it would cost $1200 to fix my a/c. That price alone sent me looking elsewhere.

The other problem is the blower motor. It cuts out all the time. Can you really replace the brushes on them or is it worth buying a whole new motor.

Any sugestions will help, because it's hot in the Mid-West. Thanks.

It is a diyer type of job to replace the a/c compressor. I would take it and have the refrigerant removed at an a/c shop (unless you have the equipment). Get a compressor, dryer and oil. After changing out these items take it back to the shop and have them vacuum/charge it. Don't forget to add oil to the compressor prior to the installation. You will need to get underneath the car to change the compressor.
The blower problem may or may not be in the blower. It could very well be in the pushbuttom circuit board. Worst case you will need to replace it. I would suggest trying to get a troubleshooting manual.

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Jim

When the blower has "cut out" (supposed to be working but isn't), try to give the blower housing a good rap (of course have the car stopped). If it cuts in a bit, odds are it's brushes and/or eccentrically worn bushings.

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

The blower motor does cut out quite often. I have the the under dash removed so I can tap it to get it going. You say the brushes can be replaced. If so where can get my hands on some.

Steve, I believe the brushes are NOT available as an MB part. I'd remove the blower assy., check if the bushings are "egg- shaped", if not; sand the commutator, pull the brushes and head off for an electric motor shop in St. Louis with them for a "closest match" and carve to fit. Some one may have a source and will chime in. How's the corn doing around Scott this year...high as an elephant's eye?

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

This seems to be a very HOT topic this time of year. I read a few threads and they say that the conversion of R-12 to the R-134a is a bad idea. I took my car down to a shop and they told me my clutch on the compressor wasn't engaging. I decided to replace it myself (after seeing the estimate). The problem is I'm not quite sure how to do it properly, but I want to take care of it pretty soon. I plan on taking the car down to have the system evacuated, then brought back to my garage for the compressor replacement. Then after many hours of cursing myself I plan on taking it back down to have it converted. My questions are: Do I need to add the compressor oil when I install the new one or do they do that when I bring the car back to convert it? Do I need replace any o-ring or fittings while I'm down there? etc....

I appreciate any help anyone can give me.

Yes the corn is growing like crazy around here.

I realize I may be comparing apples to oranges, but I went thru a frustrating experience with a Honda Accord(R-12) about 4 yrs. ago.

Local shop told me everything needed to be replaced - $1500-$2000.

You mention the clutch doesn't engage. In my case, the system was dry due to a faulty low pressure switch. $45 for a new switch, $20 for a 609 cert. and 2 cans of juice and I was back on the road. 4 yrs. later, it blows 36F out the center vents on an upper 80's - low 90's day.

Do a little digging/studying before you unload your wallet.

My 2 cents.

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Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

You will have to put the oil in prior to bolting the compressor on. Get the a/c shop you are dealing with to guide you on putting oil in it. When I replaced the comp. on my 300D I had the guy I purchased the compressor from put the oil in it when I picked it up.

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Jim

Mike,

You say that you had a faulty low pressure switch. How did you determine that it was faulty. Can I take a multimeter and determine if they are bad? When I took my car down to get checked out they had said that the system had 80psi, is that low or close to normal? Any sugestions would help before I go out and spend my life savings. Thanks.

Steve - The clutch would not engage. I either had a faulty clutch, was out of refrigerant, or had a faulty low pressure switch.

A pro at http://www.aircondition.com helped me out. He told me that Accords were notorious for faulty low pressure switches. In my case the R-12 leaked out where the switch fastens to the receiver-dryer, so I had a bad switch and no juice.

The tech had me pull the switch connection, then jumper it with a wire turned in a u-shape. The A/C switch on the dash had to first be activated. The clutch engaged. You do not want to engage for long if you're dry. This does narrow down the problem. Once engaged, I saw no gurgitation in the sight glass, especially upon activation of the clutch. I was sure the juice was gone as was the switch.

I haven't dealt with this on a Benz yet, but I suspect the process is similar

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Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

Steve - forgot to reply to all of your msg......sorry.

Is the 80psi reading on the low pressure side? If so, I'd say you may be low on juice, but then again, it could be other things. Did they read the high side too? In my opinion, a manifold gauge reading is useless unless both the low & high side are read. There are all sorts of variations of low-low, low-high, high-high, high-low, etc, and any one can indicate one of a multitude of problems.

If they only read the low side, make 'um read both the low & high together and remember, ambient(outdoor) temp. afffect gauge readings.

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Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

I spent the better part of a day replacing the compressor and the rec. dryer. I had a mechanic convert the system over to the R-134a. It worked great! I never had the R-12 in this car, so I can't compare the two. The next morning I got in and turned on the air, and there was none. I took it back down to have it tested for leaks. It was leaking right at the mainfold. The compressor I bought had the wrong instrutions it it. It didn't show how to install the o-rings for a stepped port compressor. I called the guy I bought it from for some guidance. He told me to use the yellow along withh the green o-rings. What he failed to tell me was what to do with the short sleeve that came in the retrofit kit. Has anyone done this before? If so can you tell me how you used this kit, since there are no instuctions. Any help would be greatly appreciated. Thanks.

Assuming this is an R4 compressor, does it have regular o-rings or the later sandwich type seals. I ran into this problem on my daughters car. basically the bolt would cross thread at an angle. I am talking about the bolt that is between the two hoses at the compressor.

I got a tap, carefully tapped the hole and held the line in place while I started the bolt correctly. I took the bracket loose that holds one of the lines in place on the back of the compressor above the manifold. This let me get the manifold in place and tight. Then I put the line bracket in place AFTER the manifold was tight. That was a few months ago and everything is still tight.

Good luck,

It is a R-4 compressor. The old compressor had regular o-rings. The new one has the sandwich seals. The hose manifold has the stepped ports. The discharge side had a pilot tube coming out of it whils the suction side is flat. The instrutions fail to talk about this configuration. I installed it according to the guy who sold it to me, and it leaked out in a day. We did a leak test and it is leaking from that seal ( the discharge side). Is is true that you have to use the short sleeve ( that comes along with the R-4 compressor) in conjuction whih the green seal? That's how it's desribed in the shop formum's online catalog.

I finnaly found what was wrong with the compressor. It had a hairline fracture on the suction side. I took it back and got a new one. The new compressor fit perfectly and has no leaks. The a/c works great.