*Explitive Deleted* CLIMATE CONTROL!!!!!! - PeachParts Mercedes-Benz Forum

FlossHogg · #1 03-16-2009, 06:53 PM

Okay so i have been through the diy threads.

I replaced my CCU because it had burned out. Then I replaced the blower motor on the ac. And finally I replaced the auxiliary water pump for the heater so the ccu wont burn out again. THE POS AC STILL DOES NOT WORK! I am out of ideas and dont know what to do now. Please help. Thanks.

No air hot or cold is coming from the vents.

leathermang · #2 03-16-2009, 07:57 PM

I gave up on the idea of fixing my 81 wagon AC when I found the FSM diagnostic section JUST FOR THE vertical wheel dash module was something like 80 pages....
Anyone that does not have the ' manual' type one ( like my 1980 240d ) MB AC feels your pain...
It really sounds like a power to the blower problem first.. with or without heat or air it seems it should still blow some air... (?).

FlossHogg · #3 03-16-2009, 08:13 PM

could be the blower motor regulator. would that part keep the fan from spinning altogether? can it be repaired or do i have to drop another $80 on this system and pray that fixes it?

i did get a really good deal on the blower motor and aux water pump $160 for both brand new.

WhoWhat · #4 03-16-2009, 08:16 PM

Quote:

Originally Posted by leathermang

I gave up on the idea of fixing my 81 wagon AC when I found the FSM diagnostic section JUST FOR THE vertical wheel dash module was something like 80 pages....
Anyone that does not have the ' manual' type one ( like my 1980 240d ) MB AC feels your pain...
It really sounds like a power to the blower problem first.. with or without heat or air it seems it should still blow some air... (?).

Agreed. I wrestled with my climate control for months. It sounds like the logical thing would be to test getting power to/from the blower first. If you get nothing, the relay could be bad.

Did you remember to connect 12v directly to the blower motor, just to make sure it spins freely? Even new stuff can be defective (ask me how I know). Also, check that the aux pump works too, with direct power.

FlossHogg · #5 03-16-2009, 08:52 PM

i tested both to make sure they were working before going into the SD. one of the parts that came out of the car worked as well and i decided to put the new ones in since i had already bought them anyway.

i will hit it again tomorrow when i get some daylight.

any suggestions on things to hook the tester up to would be greatly appreciated.

Ian White · #6 03-16-2009, 08:57 PM

Quote:

Originally Posted by FlossHogg

i tested both to make sure they were working before going into the SD. one of the parts that came out of the car worked as well and i decided to put the new ones in since i had already bought them anyway.

i will hit it again tomorrow when i get some daylight.

any suggestions on things to hook the tester up to would be greatly appreciated.

I had the same problem. The vac doors for heater would move but the fan would not come on. I did not want to replace the CCU so I wired up a switch and relay with a rheostat to control fan speed. I used 10 G wire and a 35 AMP switch + Rheostat. Has been working fine for thousands of miles. I have the switch and stat inside the ashtray. All the other buttons on the dash work fine. I can still get hot/cold air and in all the postitions.

Hope you solve your problem and don't have to do this

kerry · #7 03-16-2009, 09:35 PM

Does the later climate control system have a central vacuum control switch like the early servo models? If so it could be malfunctioning. On the early models if that switch is not getting vacuum or not working, nothing functions.

Oracle12345 · #8 03-16-2009, 10:31 PM

im guessing you are working on the 85 300SD.

replacing the blowermotor and auxillary water pump and CCU wont solve your problem. looks you need to test the AC system then buy what you need instead of throwing money at a problem when you dont know exactly whats causing the problem.

you have looked on the w126 service disc and ran through the test program?

FlossHogg · #9 03-17-2009, 08:52 AM

Quote:

Originally Posted by Ian White

I had the same problem. The vac doors for heater would move but the fan would not come on. I did not want to replace the CCU so I wired up a switch and relay with a rheostat to control fan speed. I used 10 G wire and a 35 AMP switch + Rheostat. Has been working fine for thousands of miles. I have the switch and stat inside the ashtray. All the other buttons on the dash work fine. I can still get hot/cold air and in all the postitions.

Hope you solve your problem and don't have to do this

I hear the vent doors opening so I am pretty sure the vac system is fine. the vac system for everything else (door locks, trunk lock, cruise, etc) is in working order. I think may be some kind of electrical gremlin.

Replacing that aux water pump was a real pain but i know it needed to be done. Since that pump burned out the ccu, what else could it have burned out?

FlossHogg · #10 03-17-2009, 11:46 AM

ok I am getting a maximum of 0.4 volts to the plug that goes to the blower motor and then nothing to the blower motor itself when this is plugged in. the vacuum door opens. i hear the ccu getting power. is the blower motor regulator the culprit? if so where exactly is it located?

Oracle12345 · #11 03-17-2009, 12:15 PM

The blower motor regulator rarely goes.

The ccu unit you got is it a new one or one of ebay? was it a known working one?

FlossHogg · #12 03-17-2009, 12:21 PM

both. the blower motor will not spin at all. it is brand new.
the aux water pump is brand new.
the ccu is working order from ebay. i tested it. its fine.

i installed all of them yesterday hoping to solve the problem but alas here i am. oh and the fuses are good.

only 0.4v is making it to the blower connector and then nothing gets to the actual blower motor.

Oracle12345 · #13 03-17-2009, 12:25 PM

have you run the manual and optical function test on the w126 service disc?

I would check the preresititance group in the engine compartment next. If its all new and non defective then I would suspect wiring, preresistance group.