Mercedes 300D W123 Climate Control Sensor Repair

The climate control on my 300D would blow full heat on any setting other than max cold. I had a feeling the temp sensor for climate control wasn’t providing correct temperature readings.

[@TylersNeighborhoodGarage]

Good job. It's a brave man who will confront both old european plastic and old european electronics in the same repair.

[@kuldipdhak7972]

Very good video troubleshooting thanks

[@tydale8629]

My foam tube had the original one and it completely fell apart in my hand. replaced it with a new foam tube just like yours.

[@alvaroamar]

Hi! I have the same ACC system on my 84' R107 280SL. I have AC if I have the wheel on full cold, but as I move it to 18, it goes hot. Im pretty sure that it is the sensor that either is missing, not connected or not working. Can you help me on knowing at least were the other end of the sensor cable goes connected? Is to the bosh grey box (Temperature Reguler I think that its called) or goes to the buttons on the center console? Do you have the sensor and cable partnumber also? Thanks in advance! Great video!

[@kuldipdhak7972]

U did not showed where u plug in sensor pins

[@ahmadkamali8547]

Good knowledge

[@mjmcomputers]

Thanks

[@jdere31760]

i wander if the sensor is some type of thermistor that can be checked with an ohm under different temps?

[@mjmcomputers]

Probably is but no idea what the values should be.

[@zorro26632]

Were you able to get a replacement tube? If so, where? I have the identical year and color as yours. I pulled out the glove compartment and found the exact same situation where the tube was missing. Thanks.

[@mjmcomputers]

No I haven’t. The pipe insulation is working fine for now.

[@zorro26632]

@@mjmcomputers I bridged the gap with flexible 5/8 OD PVC tubing. I will see how that works.

[@alvinkitzmann2134]

I ordered the mono valve replacement kit from Klimakit. They included a new replacement tube. Benefit is that I'm able to keep everything original if I want to go back to OEM, but for now- I no longer have to buy mono valves. Nice

[@drexelbeckman9519]

I have a 1985 300D turbo and the heater will only work if the battery is on but when I start the car the heat stops

[@mjmcomputers]

Sounds like a weak mono valve.

[@TheCamarokid1976]

My car is a 1985 300SD and my heater does not work any suggestions

[@mjmcomputers]

Just blows cold? Sounds like it could be a mono valve issue.

[@johnwedzicha]

And you could have put your boost gauge in that dead vent hole. lol

[@mjmcomputers]

Yeah, eventually I’ll get around to rebuilding the vacuum pods.

[@tokomarwina9964]

I have the same problem , but on the highway I don't get hot air, only below 35 mph. Weird.

[@mjmcomputers]

Could be a torn monovalve diaphragm or week magnetic coil. I just posted a monovalve rebuild video. It may be worth checking out.