Climate Control Problems on 2000 C230 K - PeachParts Mercedes-Benz Forum

N41EF · #1 10-21-2007, 01:07 PM

I have two problems with the climate control on my 2000 C230 Kompressor. It has the manual climate control that was used on the 99 and 2000, and seems to cool well, however it has a couple of bugs.

The first is that when you press the button for the EC which is economy mode switch, nothing happens. I can't hear any flaps moving, don't hear the a/c compressor cut off. The light in the switch doesn't light up, and I've tried it with the fan on, off, engine running, and off. Any ideas?

The second issue is that when I turn the air distribution control switch, nothing happens. I get cold, warm, or hot air out of the center vents, some air flow out of the defroster vents, and a trickle out the side outlets. I verified engine vaccum is on the inlet to what appears to be a control valve, and verified when I apply a vaccum to the valve and operate the function switch, nothing happens. The control valve I believe locks the vaccum in the resevoir and seems to function correctly. When you turn the temp controls to max they click and the blower kicks up. The blower speed seems to operate as it is suppossed to. It's as if the knob isn't connected to anything, or a fuse somewehere isn't supplying power to a change over valve or something. Where is the valve that changes over the modes and such? Is theis related to me not having an economy mode above?

Thanks, Chuck

300B · #2 10-22-2007, 08:57 AM

Possibly.

Have checked to make sure your evaporator temperature is working correcting via the N22 diagnostic mode?

N41EF · #3 10-22-2007, 07:24 PM

I havent run any checks. does the manual climate control have a diagnostic mode? what doe the N22 refer to? Thanks, Chuck

300B · #4 10-22-2007, 08:50 PM

It's the code for the climate contro; unit.

You press and hold the the REST button for close to ten seconds and a diagnostic can be performed.

Here's what the codes represent:
01 = In-car temp sensor
02 = outside temp sensor
03 = left heat exchanger (heater core) temp sensor
04 = right heat exchanger sensor
05 = evaporator sensor
06 = coolant temp
07 = refrig. pressure in bar
08 = refrig temp sensor (23*9 = 23.9deg C)
09 = nothing
10 = Blower control voltage (great for evaluating blower controller problems)
11 = emissions sensor (B31) e.g. 3.1 = 31.v
12 = sun sensor 4.2 = 4.2v
20 = aux fan control 6.1 = 6.1ma (max 10ma)
21 = engine speed
22 = vehicle speed
23 = Circuit 58d e.g. 99 = 99% of battery voltage
24 = BATTERY VOLTAGE e.g. 12.5 = 12.5v
30 = left rear air conditioning heat exchanger temp sensor (not all vehicles; obviously)
31 = right side
32 = rear evap temp sensor
33 = blower control voltage rear 0.8(MIN) - 6.0(MAX)
34 = left rear temp selector
35 = right side
38 = software status e.g. 37 rear air conditioning
40 = control module version software status (?)
41 = control module version menu hardware status
42 = control module variant code 1st number
43 = variant code second number.

N41EF · #5 10-23-2007, 07:17 PM

Okay, I had the ignition on, car off, and pressed the rest button, and other than the red light going on, or pressing it, and the red light going off, Nothing happened. I can hear a vaccum flap moving when I turn off the blower with the car running. Also tried the hold the rest button with the car running, no change. The car is the manual climate control, doesn't have the digital display. I have read many threads about the evap temp sensor, is it something I can check with a meter? I'm guessing it's a temp/resistor, anyone know what it should read (besides open or shorted). Thanks again, Chuck

TimFreeh · #6 10-24-2007, 10:03 AM

Quote:

Originally Posted by N41EF

The car is the manual climate control, doesn't have the digital display. I have read many threads about the evap temp sensor, is it something I can check with a meter? I'm guessing it's a temp/resistor, anyone know what it should read (besides open or shorted). Thanks again, Chuck

The manual version of the W202 climate control system does not have the LCD panel and you can't read the actual values via the panel. The system does have diagnostic codes that can be retrieved via an MB scan tool.

I don't think the manual system uses vacuum pods to direct the airflow - I'm pretty sure it uses some sort of cam mechanism to directly move control flaps based on the position of the rotary selector switch on the front panel. When the panel is removed you have to line up a male/female nylon rod that transmits the movement of the control knob into the innards of the HVAC box - if the HVAC control head was removed at some point in the past its certainly possible the control rod was not properly reconnected. You should be able to feel some resistance as you move the air control rod through a 360 degree range. If you don't feel differing levels of resistance (and hear things moving around inside the dash) you need to remove the control panel and check the nylon rod to see if its correctly installed.

Test values for the evap temp sensor are

temp 10C -> 5.2-5.8k Ohm, 20C -> 3.2-3.6k ohm, 30C -> 2.0-2.3k ohm, 40C -> 1.1-1.25k ohm

cudaspaz · #7 10-24-2007, 10:10 AM

Most likely needs a new push button control unit.

Pretty common issues.

N41EF · #8 11-04-2007, 07:55 PM

Just a post for closure. The manual climate control does in fact use two nylon shafts and sockets to actuate the lower and upper flappers. I removed the glove box and radio and could feel that they were disconnected. By removing the lower two screws I was able to swing the bottom of the panel out enough to allow the rods and sockets to be connected. I did some sole searching to figure out how to line them up. Wound up feeling the output shafts while I turned the distribution knob, and figured out if the sockets should be clockwise or counter-clockwise. Seems to work great now. The only vaccum item is the recerc flapper which seems to operate correctly. Only thing not uo to speed is I still have no EC light, and it doesn't seem like the a/c compressor drops out. As I type this with scratched up hands, I'm still glad I bought a car with manual, since I now can skip reading all of the posts that discuss vaccum pods and climate control. Thanks folks! Chuck