Mein AC ist kaput... - Page 3 - PeachParts Mercedes-Benz Forum

MercFan · #31 11-01-2009, 04:43 PM

Quote:

Originally Posted by Craig

Yup, that's a common failure. You don't need a whole valve, just the "repair kit":

Ok - I'll spring for the repair kit on this. I hope that puts us one step closer to the properly functioning ac. Thanks for your guidance Craig.

I think I'm going to re-assemble that valve anyway (for now) and then I'm going to pinch a hose and see if it makes a difference temperature-wize inside the car - think it should... I'm hoping to get at least the outside air blowing in with that hack in place.

#32 11-01-2009, 05:07 PM

Quote:

Originally Posted by MercFan

Ok - I'll spring for the repair kit on this. I hope that puts us one step closer to the properly functioning ac. Thanks for your guidance Craig.

I think I'm going to re-assemble that valve anyway (for now) and then I'm going to pinch a hose and see if it makes a difference temperature-wize inside the car - think it should... I'm hoping to get at least the outside air blowing in with that hack in place.

That should work, some people have put manual valves from the hardware store in the heater hose to stop unwanted heat. Closing off the hose should at least get you ambient air, then you can start looking at the AC system.

Don't feel bad, I just spent about $2000 fixing my AC system after the compressor blew up.

MercFan · #33 11-01-2009, 05:14 PM

I made a rookie mistake... forgot to make a note on the order of the washer, the spring and the plunger component... is there an exploded diagram that shows the sequence of these in the right order?!

THx

james

#34 11-01-2009, 05:22 PM

I don't have anything with me (I'm 1500 miles from home), and I don't remember the details. If no-one else chimes in you might want to start a thread to ask that specific question.

MercFan · #35 11-01-2009, 05:23 PM

Quote:

Originally Posted by Craig

I don't have anything with me (I'm 1500 miles from home), and I don't remember the details. If no-one else chimes in you might want to start a thread to ask that specific question.

http://mbdieseldiy.tripod.com/images/11a.jpg

charmalu · #36 11-01-2009, 11:28 PM

http://mbdieseldiy.tripod.com/monovalve.htm

charlie

MercFan · #37 11-01-2009, 11:44 PM

Today I started the engine and with the defrost button on I measured the voltage going to the terminals that plug right into the compessor in the front of the engine - the reading was 0.00V - each time I clicked a new button, I saw the voltage jump to .90-.95V and then immediately settle down to 0.00V

So what does this tell me - do I need to look at the AC relay (KLIMA), or does this just further confirm that my ACC unit needs to be replaced...?! Any guidance will be appreciated.

#38 11-02-2009, 07:18 AM

Don't know yet, it might just be the pressure switch preventing the compressor from starting due to a lack of AC charge. Have you done anything to determine if the system is charged or leaking yet?

MercFan · #39 11-02-2009, 10:08 AM

Quote:

Originally Posted by Craig

Have you done anything to determine if the system is charged or leaking yet?

Not yet... I'm going ot have friend test, flush, refill the system on Wednesday night. Will report back with the findings...

MercFan · #40 11-04-2009, 12:07 AM

How can I test the aux. water pump on the vehicle?! Do I connect the battery directly to it, or some other way?! What is this pump really for and what would be a result if it wasn't working right?!

THanks,
James

MercFan · #41 11-19-2009, 07:22 PM

Today I replaced the monovalve with a brand new one. Went for a ride - it seems there is no change in the condition. With the temp gauge set at 26C I can click any of the buttons (except off) and no matter what I do I always get heat. The fan speed low/high works fine, so I either get low heat or high heat... The heat is never-seizing. I even adjusted the wheel position mid-trip to cold still no change in heat output - dont think I'm even getting outside air - only the constant heat. So...

I was thinking that for some reason the ECC does not recognize the proper cabin temperature, perhaps? Maybe the cabin temp sensor is unplugged or broken?! If so, how/where do I check it - under glove box somewhere? Thoughts?

James

MercFan · #42 11-21-2009, 12:25 PM

Today I inspected the cabin temp sensor on top of the dash under a tiny little vent. Pulled it out gently, lifted the miniature circuit board out of there just so I could get my ohm meter on the leads at the bottom of the tiny circuit board. The resistance shown was an open circuit - does anyone know if that's right?!

Top of that tiny circuit board has what looks like a capacitor spanning the two sides of the circuit board so maybe an open circuit makes sense... Anybody?

Edit: Per Jeremy - the top component in that tiny circuit board is a 'thermistor' - which is a temp-sensitive resistor - makes perfect sense. The bad news is that open circuit means a bad component - off the find a replacement. If you have one PM me.

The foam hose in the glove compartment is torn and I need to replace it.

MercFan · #43 09-15-2010, 01:04 PM

I need to resurect my old thread here...

Since last time I have replaced the cabin temperature sensor and replaced the foam hose under the glove compartment, hoping that this will better register the actual temperature in the cabin and allow the AC control unit to function properly.

I started the car, I measure the voltage to the plug that goes to the compressor (photo1) but it registers 0.00V no matter what setting I have. In fact, it registered 0.00V and didn't even move when I unhooked the battery from the car so it looks like it sees an open circuit somewhere.

Picture 2 is a KLIMA relay sitting next to its socket base.

Where should I go from here?! I'm thinking of heading down to see my AC buddy to measure the pressure in the system next.

Any advice on how to troubleshoot the KLIMA - any specific pins that I should check for resistence - an electrical diagram would be very useful if someone had that -

Thanks,
James

Hit Man X · #44 09-15-2010, 01:17 PM

Jump the Klima and see if you have power at the plug. Mine was dead on the SD when I rebuilt the AC system last season. The relay was about $120 when I replaced it. Also you should not have power at the plug due to the pressure switch cutting the compressor out when the system is low...

1985 300SD 617 Aux Fan & A/C Thoughts + Help Needed

Post 11 will help to jump the Klima.

You could also have a dead PBU, but I did not read the rest of the thread.

MercFan · #45 09-15-2010, 03:06 PM

Quote:

Originally Posted by Hit Man X

Jump the Klima and see if you have power at the plug....

THanks HitMan -

I jumped the KLIMA wires according to the pic in the link you provided, but still no change in voltage (car running, clicking various buttons on the PBU, fan running).

Still no change in the voltage on the plug. I guess I'm going to pursue making sure we've got pressure in the system just to check that side of the system?! Unless there are other recommendations to do next.

I wish there was a way to isolate or emulate the proper PBU output to see if that part is working right....

Any advice would be useful -

Thanks,
James