psiegel

Is there a relationship between no air coming out of right defrost and left foot well or is it just a coincidence and that in fact i have two separate problems?
Thank you
Peter

stevepaa

Please describe your problems.

tbennett017

Those sound like separate servos, but it could be related upstream.(CCU) There are 4 servos in the car that control the airflow... 2 on each side that control defrost/floor, and hot/cold.

mojorizing

Peter,
What happens when you press the defrost button? Max air from the windshield vents?

psiegel

When I depress the defrost button i get the same flows as when I move the upper slider all the way to the right and turn the fan on to 4, meaning it comes out great from the left windshield vent and nothing out of the right windshield vent.

The opposite happens for the foot well vent air flow, Meaning when I move the bottom slider all the way to the right and put the fan on 4, i get good flow out of the lower right vent and nothing from the lower left vent.

Does this make any sense?

Peter

mojorizing

Interesting...
When you move the upper slider to the left, do you have air flow from the right side air vent (make sure the knurled wheel beside the vent is open)?

The left and right fans have their own mixing hot/cold servo and temp sensors but they discharge into a common plenum where servo controlled dampers direct air to left/right windshield, left and right center and side vents, and also another damper to the left/right foot wells. Unless there's blockage into your right windshield and the left foot well ducting has been disconnected from the airbox...


This post has some pics>>>>
https://rennlist.com/forums/2900675-post17.html

psiegel

No air to the right windshield vent when i move the upper slider to the left and yes all the vents are open.
So it could be servos or the ducting? Can you tell me where i can access the ducting?
Thank you

DWS964

Just an additional data point - I have the same scenario present in my car - little/no left footwell and right defrost air flow. I know that there is an issue with the left side blower motor - something appears (sounds) to be interfering with it, and doesn't seem to run until the max blower position. So, I wonder what the air flow distribution/pattern is within the unit, with contributions from each fan. I did have an issue with the right side mix chamber servo that caused a temperature control problem, but has been corrected.
Obviously, I need to access the left blower and correct that issue.
Have you run a diagnostic with the Hammer or Scantool on the CCU? it will cycle through all the servos and fans, and report codes.

mojorizing

@Peter,
With the top slider to the left, are you getting air flow from the right side vent (not the right-side windshield)?

@Darrell,
If it's a temp problem then it's associated with the two servos/dampers/damper door seals, etc. but a flow problem points more to blockage at that particular damper. I'll disable one of my fans and see if it decreases flow to that side only....

mojorizing

Darrell is correct in the air flow situation...
Today I hooked up my Hammer, closed all dampers except the windshield, and ran each fan separately. What happens is the air flow appears on the opposite side of whatever fan is running - left fan running, air flow on right side windshield. Doing the same with only the footwells open, I see flow from the same side as whatever fan is running - left fan running, left footwell has flow. I think this can be explained, like Darrel mentions on the internal structure of the airbox - left fan discharges to the right, therefore right side windshield gets most of the flow. For the footwell, I'm thinking there's baffles to direct air down into that area of the airbox for the respective side.

So, Peter I think you might want to look at your lefthand blower.

mojorizing

As an interesting note I found this post>>>>
https://rennlist.com/forums/964-foru...and-drive.html

It shows linkage from the rightside footwell that drives the leftside footwell damper. If you ever find that you can't get a change of air flow from the leftside footwell, this could be your problem. The bad news is that you need to remove the gas tank and HVAC system because it's located underneath the airbox. This is not your problem, Peter, just an FYI.

DWS964

Thanks for performing the experiment and confirming my theory. This gives me confidence and incentive to fix my left blower.

psiegel

To answer your question, when the slider is all the way to the left i do get flow out of the right side and the left side vent. When the slider is mover to the right, i still get very similar if not the same flows out of the right side and left side vents.
Regarding the post about the left side fan, this is starting to make some sense. After I read this, i turned on the fan speed to 4 and felt both fans, i did get more vibration out of the right then the left fan. If the left fan is not running then the vibration from the right fan is transferring over to the left fan. Is this possible that it could do that and give me a false sense that the left fan is running but it really isn't? Is there an easy way to check to see if the fan is actually running? Okay one more question, if it isn't running is there a way to figure out if its the Fan, wiring, CCU, relays, etc.
I want to thank you so much for your help on this. You have certainly gone out of your way.
Thank you
Peter

mojorizing

Other than listening and feeling the fan housing, there's no easy way to tell if the motor and fan are running. The wire loom to each fan doesn't provide a connector to test for voltage. The power for each fan comes from the "blower final stage" which basically amplifies the control signal from the CCU.
If you can't physically tell if the fan isn't running, it might be best to get a scantool or the use of a hammer to pull the codes from the CCU and to cycle the fans (drive llinks, it's called). There was a loaner scantool floating around the forum, and there's RicardoD soon offering the hardware.


Here's an option:
Do you have a VOM that can measure 10-20amp DC? I can measure the amp draw from the battery with both fans running and if you have considerable less than this, I'd say only one fan was running. However, this isn't conclusive due to all the variables..... for example, the motor might be running but the fan is spinning free or broken,etc.