Back at it . . . or almost. I toasted my spare ice-cube so I have four on their way. Additionally, I found a Klima for $40 and that has been shipped. I do intend to eventually find all of the gremlins and use the Klima the way it was intended.

I also had another dilema while testing. I had two multi meters and now I have a third. My digital ran from the vehicle battery so when I had to use one Klima socket for ground and another positive I had to switch to my little needle meter. It wasn't designed for automotive use and the voltage scale imposes real limits (10 volts, 100 volts, etc.). So today I went to Sears and purchased a relatively inexpensive digital that gives me more meter than I need. Actually, since it has the temp probe I can monitor my ACC temps from the vents once I get the ACC operational again.

While I'm waiting for delivery of my relays, I want to keep testing. An area I am uncertain of (there are still many of those) is the air gap on the compressor's clutch. First, if by jumping 5 & 7 at the Klima socket engages the compressor is it safe to assume that the air gap is approximately correct? If I do need to check it, is there a nut to remove at the front (after loosening the belt) that will provide access to the clutch components?

I'll keep you posted.

P.S. Brier, my bulldog seems to be doing better. He is snoring up a storm at my feet as I type. I think the brief ride in the MB yesterday did his spirits some good. He still prefers the '77 VW 7-passenger bus since he can stretch out and snore. Just over eight years old and with a life expectancy (according to the breed) of 8-10 he is probably doing as well as I can expect. What big babies these four-legged family members can be.

__________________
Steve
'87 300TD - 132K - Soon 4-Sale
'84 300D Turbo - 122K - Driving
'77 VW Type II - 77K - Restored
'08 250EX Ninja
English Bulldog (Brier) - My best friend. Passed away 12/02/04 while in my arms.

Steve -

Didn't you post the air gap question in a separate thread? I think I answered there. Either that or I'm hallucinating again. Wouldn't be the first time.

Anywho, long and short is no, jumping the Klima and having the compressor engage is no guarantee it'll work with a good Klima in place. Mine worked fine with an ice cube relay, but would cutout with a Klima. Check the air gap and I bet you'll find it to be 0.8-0.9mm. That's flaky territory - the compressor is capable of working OK, but there's enough clutch slip to trigger the Klima speed comparator circuit.

Setting the air gap is pretty easy. Remove the 10mm nut which retains the front plate of the compressor. You need a special puller to remove the plate. It's nothing fancy, most McParts stores will rent/lend you one - I bought mine for ~$20. Space may be tight between the clutch plate and the radiator. With the clutch plate removed, you'll find one, or two, or maybe three small washers on the compressor shaft. These are spacers. Try removing one or two of them to see which result gets you closest to 0.50mm. Don't go below 0.35mm - that's minimum spec. If you wan to be really obsessive about it, your local auto a/c place will sell a kit with a variety a spacer rings so you can set it just right.

Assuming you can get the clutch plate off the front of the compressor without pulling the radiator it's a 15 minute job.

Good luck,

- JimY

Jim,
You are probably not hallucinating . . . its just I was lost from before starting since I did not know where & how to set the air gap. That being said, thank you for the instructions because I will have NO problem following them. Though I own a number of pullers, I will check to see if they have one at the local parts shops for AC pulleys. I noticed the lack of room when I changed to the newer type vacuum pump w/o having to remove the fan & front portion of the shroud. Being the careful type and having reasonably good right/left dexterity, I should be able to accomplish it w/o damaging the radiator.

I'll keep you two posted and also be anxious to try my new temperature probe on the cold air that will be coming through the vents.

P.S. Tried my new digital multi meter on the Klima socket tonight with terminals 5 & 10. It worked like a charm giving me < 1 volt in digital. Should have updated my equipment long ago. The audible feature was a help since I didn't have to take my eyes from the probe placement as I went all over the place checking resistance (olde boys with new play toys).

My two sons (24 & 25) and their friends have really started to take an interest in my '87 300TD. They wanted to borrow it for their Friday night trip to Epping, NH drag raceway. They all drive the new vehicles yet wanted to take my diesel wagon . . .

__________________
Steve
'87 300TD - 132K - Soon 4-Sale
'84 300D Turbo - 122K - Driving
'77 VW Type II - 77K - Restored
'08 250EX Ninja
English Bulldog (Brier) - My best friend. Passed away 12/02/04 while in my arms.

I am attempting to pull the compressor clutch in order to check the air gap. How in heck do I hold it from turning so that I can loosen the 12mm nut?

__________________
Steve
'87 300TD - 132K - Soon 4-Sale
'84 300D Turbo - 122K - Driving
'77 VW Type II - 77K - Restored
'08 250EX Ninja
English Bulldog (Brier) - My best friend. Passed away 12/02/04 while in my arms.

You know, I can't remember what I did to hold the clutch plate from turning. I don't think the 12mm was all that tight when I worked on the compressor. How about a strap wrench, like for a spin-on oil filter?

BTW, here's a link to a site which explains rebuilding a nippondenso compressor. Most of it isn't relevant, but some of the photos & steps might apply to your task. http://www.pelicanparts.com/techarticles/911_Nippondenso_rebuild/911_Nippondenso_rebuild.htm

Best of luck,

- JimY

Just received my shipment of ice-cube relays and what was supposed to be a new Klima. The latter was a fuel pump relay so the Klima is now being shipped tomorrow.

So, I took the next step and wired the ice-cube the correct (thanks) way. As you guys already knew, it worked. YES!!! Cold air again!!!

Thanks for the suggestion of the strap wrench for holding the compressor clutch plate (not certain if that is the actual name). One of my boys heard me say something like, "what a dumb sh_t I am" and asked what was up. I told him what you suggested and he agreed with my self assessment. He took it one step more by reminding me that I usually do a better job thinking of things than McGuiver. Guess the frustration was taking its toll.

I am hoping that I'll have access enough to check the air gap since I am not equipped to remove the compressor.

With patience I'll be able to get the Klima back in and working as it was designed. Keep you posted.

PS Don't know if either of you happened to see my stringtrimmer line lodged in the sunroof post or not. While using the line to clean my rear drain tubes I got the line lodged tighter than tight in the rails of the sunroof. That was a couple weeks ago. I tackled removing the sunroof lining for the first time this morning and was eventually able to free the line. Now I just need to read how to adjust the micro and/or clutch stops. I tried for awhile with the white knob near the motor and that seems to be the way to do it (used a 3mm wire in the hole). Not quite correct yet but closer.

Thanks again guys. The cold air seems great.

__________________
Steve
'87 300TD - 132K - Soon 4-Sale
'84 300D Turbo - 122K - Driving
'77 VW Type II - 77K - Restored
'08 250EX Ninja
English Bulldog (Brier) - My best friend. Passed away 12/02/04 while in my arms.

After cleaning up my ice-cube relay wiring job (shortened the wires and made a decent under-hood fit) I spent time driving my '87 300TD with AC on to see what type of readings I would get at the vents. Using my digital multi meter with temp probe, I got a sustainable low temp of about 47-48 degrees at the center vents. Ambient temps during my trials ranged from just over 80 to mid 70s (most of the time). With AC on the engine temp was primarily just over 80. Idle, of course, resulted in the vent temps to climb but no more than I would expect. Though I am going to eventually complete the task of finding (expecting the compressor clutch gap) the problem, solving it and getting a Klima back in, I am thrilled with the help/results. I'll keep you posted.

__________________
Steve
'87 300TD - 132K - Soon 4-Sale
'84 300D Turbo - 122K - Driving
'77 VW Type II - 77K - Restored
'08 250EX Ninja
English Bulldog (Brier) - My best friend. Passed away 12/02/04 while in my arms.

I've got similar problems with the Klima on the SDL. I traced it down to the compressor speed sensor. The sensor should provide a reading of .3V at idle. It provides less than .2V. It should have a resistance of 550 to 650 ohms. It has 1000 ohms.

It appears that this speed sensor is on the back of the compressor on the shaft centerline.

There is some mention made of an air gap. But, I'm thinking that it's not applicable to this unit?

Can anyone, maybe Arthur, comment on how the speed sensor would be setup on this compressor and how to remove it??


Edited:

After making up the bypass ice cube relay and installing it, the problem is identical:

The compressor runs for about four minutes and shuts down. No change in symptoms.

So, the low pressure switch is ruled out, the Klima is ruled out. What else can possibly shut the compressor down and leave it shut down?

I started another thread on it. I'm at a loss.

300 SDL A/C electronic controls

Brain,

I had a similar problem. Compressor sensor resistance was not correct. Replaced the 3 wire connector on the compressor, AC works fine!

__________________
Zafar
94 E320 58000 Miles

Yes, I thought that was the case with this one, as well. But, removing the Klima from the system and running it with the ice cube relay confirmed the problem remained. So, the sensor on the compressor was doing the proper job.

If you bridge pins 5 & 7 on the Compressor Relay Socket, does the compressor continue to run?

__________________
Zafar
94 E320 58000 Miles

Yes, it did.

Looks like you have already ran the 6-7 tests for the Compressor Clutch Relay.

You may want to run the AC Control Unit Diagnostics. alldatadiy lists all the tests.

The compressor engagement on my car was intermitent. Then it would engage at startup but disengage shortly. Bridging pins 5 & 7, the compressor stayed engaged. Repalced the Compressor relay. Did not fix the problem. Took it to the MB dealer, that is another story! I have yet to find a satisfactory MB dealer. End result, I was overcharged and problem not fixed. I declined the $675 speed sensor repair. For that price, one can get a new compressor!

Ran my own checks, all 6 of them for the compressor relay. Ordered the ICe Cube Relay from ebay. Meanwhile, found power connector at compressor loose. Replaced connector, around $5. Everything working fine. Temperature at the vent 38F.

__________________
Zafar
94 E320 58000 Miles

Bridging pins 5 and 7 eliminate the Klima and the PBU from the system. So, you really don't know anything, at that point, other than the compressor clutch works properly. The problem can then be any of the signals to the Klima, the Klima itself, the PBU, or any of the signals to the PBU.

In my case, using pin #10, the ground from the PBU, the problem remained. So, this now effectively rules out the Klima and all inputs to the Klima.

A second PBU eliminated the problem, however, it's more likely that the evap temp sensor is out of limits (2.2K resistance) and causing a default in one of the PBU's. They are not exactly identical........one of them is a newer version and must have slightly different internal circuitry.

I hear you regarding the dealers. You take the vehicle there thinking that they have better knowledge and troubleshooting skills than you do. In reality, you get a parts changer with his head up his ass.