vito 110 cdi vacuum hoses and cabin heating problems!!

[dazboy]

Hi all, i'm new to here and new to MB in general, have owned loads of different makes of vehicle and never had a problem solving problems or repairing compared to the Vito! I have a vito 110cdi 2.2, which i have turned into a day bus for our weekend events we carry out, i have the usually problems with vacuum hoses and heating. i have checked most of the vacuum hose points i can find and have fix/replaced them but i have found the sensor behind the air intake against the bulkhead thinks its the inlet port shutoff, i found the "Y" at the bottom with one of the branches going nowhere with nothing in it. Should it go somewhere or if there suppose to be an air filter on this branch.
Also problems with the cabin heating only blowing hot and fan speed not 100% only works when pushing the rest button. No air con or circulating fan. Have checked the fan and replaced brushes, the resistor pack has been sent away and test/checked and found to be 100% ok, Pollen filter changed and all fuses checked any ideas out there????
Cheers
Darran

 

[Danny DeVito]

i found the "Y" at the bottom with one of the branches going nowhere with nothing in it. Should it go somewhere or if there suppose to be an air filter on this branch.


Show me a picture of this

 

[Danny DeVito]

Where did you find the resistor pack exactly ? It sounds like the heater control unit is missing an input more likely not outputting any power. The fan blowing when you push rest suggests that the unit is getting power. The unit is behind the heater controls on the dash. Recently on mine i discovered that the 1st fan speed does not work. Because my air con is disconnected i can press the aircon button and the first speed fan comes on. So obviously fan speed 1 works. So this is why i suspect the speed selector dial is not passing on the power. I have not looked at it yet, perhaps we can sort it together. Also it would help me that if you remove ur unit could you take a clear picture of the back where the cables attach in the middle. My bits broke of and i want to try rebuild them.
The bit where it only blows hot.. again it is controlled from the heater unit and it outputs power to a motor under the dash which controls the heat level. The motor is to the right of the heater matrix. i think its visible when u remove the center fascia. The motor may be stuck or something. Maybe some of this info will help for now, we can start looking at wiring diagrams after you do some more visual checks.

 

[dazboy]

Cheers for the reply, the resistor pack is under the dash passenger side just to the right of the fan motor itself, has a plug on it with 4 cables on it. I removed it thinking my heating problems were down to this after checking other forums. There is a fella on e-bay that repairs them for £17. I sent it off and he tested it and found it to work fine so sent it back and refunded the money. I also replaced the brushes in the motor which wear. Doesn't make any difference where the temp dial was positioned always hot 99% of the time, on a run sometimes gives cool air for 30 mins then back to hot. I think there could be a sensor in the bumper under the number plate, bugger to get to but when i bought my Vito the bumper was cracked and the sensor is pushed up now could be a factor. I will try to get my control unit back out Tues and take a photo for you. Any idea where the air con relay pack is if you have discounted it so i can check it. Would be good to get it sort now the warmer weathers coming????
The "Y" vacuum pipe i think goes to a small filter looking at my workshop manual but it only shows drawn images rather than pics so not great at making it out, again i will strip the airduct off and get a photo of it on Tues.

 

[Danny DeVito]

is ur temp control manual dial ?

There is a temp sensor under the bumper alittle to the passenger side. Sensor on the dash too beside the buttons in the centre. looks like lines crossways.

Have you had aircon pressure tested ? If its low or high then aircon will not start . The dash light will come on but no air con operates. The hi/lo switch is on top of the drier just behind the rad. ontop of silver canister. if u unplug it the rad fan will blow.

 

[dazboy]

Hi Dan,
Soz late reply, i've just taken the bumper off as it needed fixing and spraying, found the sensor which looks ok but was not where it should be. Noticed over the weekend end that on a good running on motorway i did get cool air but when slowing / stopping temp rises so could be the sensor not getting the correct airflow due to the position. i will check the air con later and will get the dash apart again to check sensor in there which i have checked before. Also then flap for position of airflow is jamming so need dash out to replace. Will also check the actuator by the fan so see if thats ok.
I will get you a pic of the engine u needed this week.

 

[Danny DeVito]

Diagram for heater wiring, looks fairly straightforward to test