AC stopped blowing - PeachParts Mercedes-Benz Forum

#1 08-23-2002, 12:03 AM

My '92 300e air conditioner stopped blowing. But came back on for awhile then stopped again. Now will not blow at all? Is it the blower or the control panel? How do I diagnose this?
Thanks in advance.
Hank

Piotr · #2 08-23-2002, 12:16 AM

sounds like a low refrigerant-check if you need to recharge the system

#3 08-23-2002, 03:02 AM

this happened to me and turned out to be a loose wire close to my oil guage behind the dash. I diagnosed by pounding around diff parts of the dash. Whe I hit the bottom of the dash under the steering wheel, the a/c came back on!

#4 08-23-2002, 06:32 AM

It could also be a slipping belt. If the a/c clutch is engaging and the fan is still off, there is probably an electrical connection problem in the fan motor circuit, or the motor is worn out.

I know this doesn't narrow it down much, but maybe it will be helpful.

Have a great day,

jeffsr · #5 08-23-2002, 06:33 AM

Number of things to check. First, the fuse, located outside the fuse box forward of the firewall bulkhead, near the edge of the fender (on the driver's side) in a little black plastic holder with a wire exiting from each end. Pop this open and check the fuse. Use a test light to see if you have 12 volts on either side of the fuse. If that's OK, call back here and we can dig a little more. It sounds more like brushes than anything else. What's the mileage??

joe p · #6 08-23-2002, 08:00 AM

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Check the flat fuse in the little black box in front of the main fuse box under the hood first, check for cracked fuse and for power.

Then check for voltage and ground to the blower motor itself. Odds are youve got a bad motor.

Joe

#7 08-23-2002, 10:14 AM

I checked the fuse and voltage, both checked to be ok. However the a/c did work this morning. But then stopped again. Does the auto climate control have anything to do with this?

joe p · #8 08-23-2002, 10:37 AM

odds are, no, when its down make sure the flat fuse has power, I've run into ign switchs doing this.

Joe

#9 08-23-2002, 01:00 PM

Is there a blower regulator motor I can check?

joe p · #10 08-23-2002, 03:33 PM

the blower regulator on the 124 is wrapped around the bottem of the blower moter, under the cowl......

Joe

#11 08-23-2002, 03:44 PM

Give it a good Fonz like I did. You never know..

saumil · #12 08-24-2002, 09:18 PM

Hi,

Check the voltages on all the pins of the 3 pin connector under the hood (it is on the driver side, near the fuse box). The female plug easily comes off. One of the pins should have the battery voltage, another pin comes directly from the climate controller. This voltage varies and is the control voltage that goes to the blower regulator. I will have to double check my CD, but the voltage varies between some 2V to 6V or something. If I remmber correctly, the third pin is the ground pin. If you want details of the which pin is which, email me and I will look it up.

O.K., now here is what to do. Put the climate control settings so that the blower motor runs say on the fast speed (dont put it on auto). When your blower motor is working, note down the voltages on the two pins that are not ground. Do the same when the blower stops. If you see that the battery voltage has dropped, the problem is your ignition switch, replace it. If you see the control voltage drop, then the problem is in the climate control unit, before replacing it, open it and check if it is not just a cracked solder anywhere. If both the voltages are the same when it is working and not working, then the problem is with the blower regulator or the blower. For this, you will have to access the blower and the regulator. Once you have access, get the blower motor out and test it with a battery charger, let it run for an hour or so, if it runs fine, it is not the blower. Replace the blower regulator, very expensive part.

Good luck,

Saumil

#13 08-25-2002, 08:40 PM

I had it fixed over the weekend. The total cost was $20.00. They put a shiny chrome thing across two connectors which was located next to the fender in front of the fuse box.