HVAC & what could be the issue

When Shane took delivery of what later became the orange Joyride GT, one of the issues it arrived with was the inability to provide heat to the cabin coupled with air out the vents only - no defrost, no air to the floor. Since the car was in AZ, this is almost never an issue and so the car was never repaired. That is until last May when a couple other issues arose - I started digging around to fix them & decided to take care of the HVAC issue. Here's what I found;

Issue #1. No directional control

Turns out that when the foam was applied to some of the doors that direct the air in the duct system was applied it was stretched - when the adhesive got hot, the foam withdrew & exposed the adhesive. This is good adhesive and it has no problem gluing the door in place! The fix for this is to VERY GENTLY free the door by VERY GENTLY pushing it away from it's seat - just enough to un-stick it and open it further using the dial Ford intended you to operate it with. Now that the door is unseated you need to make sure it wont get stuck again. Silicone grease does a great job, does not smell and wont get hot and become runny. Apply it to the sticky edge of the door and to the seat on which it rests.

Issue #2. Blend door - Stripped servo motor

My guess is that this issue was a result of the same foam "shrinkage" that caused the above door to remain stationary, the difference here is that the servo gears were damaged from repeated attempts to adjust the air temperature. In the "cold" setting the blend door is roughly horizontal with a pivot at about 85%. That's confusing, but if you watch the video you'll understand.

These little servos and gear boxes that drive the doors are probably pretty inexpensive but they are not available as components, you'll have to either order the complete duct work assembly or attempt to break the epoxy bond between the servo, gearbox and door. Both methods would require the dash to be completely removed from the car. Nasty.

After some experimentation, I discovered that if I applied some force to the 20% of the door that moved downward when the request for heat was given- the door would move and operate normally. My solution was some lead weights used to find proper CG in model aircraft and some aluminum tape from the hardware store. As you can see in the photos and video I carefully measured & cut the lead weights (they come adhesive backed) applied two rows and covered them with aluminum tape for extra security.
[video=vimeo;32026828]http://vimeo.com/32026828[/video]

The system performed flawlessly after these repairs were made :thumbsup

Here's a couple FYI's

The control system for the servo's send instructions in "units". So, under normal conditions the blend door may require 100 units to travel from completely closed to completely open. The point here is that the position of the control knob may not correspond with the position of the blend door, this scenario would likely be due to a damaged servo gear box that has "jumped a tooth" (or more).

I used a Milwaukee flexible camera to help diagnose the issues. You can find them at most home improvement stores.

The stereo console had to be removed as well as the lower part of the duct work - the piece that diverts air to the individual foot wells. I didn't take any photos of that particular piece. You may be able to get the camera in there to see whats going on from the fresh air vent located under the boot lid. It has a stainless steel screen cover secured by some phillips head screws.

Thanks for the :thumbsup!!

fjpikul said:

You remind me of a gynecologist.

Click to expand...

Uh.... That's good right?!