'63 heater airflow problem

[Erik H.]

I'm continuing down the PV checklist, and I'm not sure what to make of the airflow from my heater box. I have strong airflow from the defroster vent when pulled on, but I don't seem to have any airflow from the Y duct or driver-side duct when the heater control is pushed to any other setting.
When in non-defrost heater mode, I'm getting a lot of blower noise in the box at full speed because it sounds like it's sealed up and the air can't get out. Seems odd to me that the defrost mode opens and closes the flap like a charm and yet I'm getting nothing in plain heater mode. Any idea what's wrong and where to start? Hope it's an easy fix, and appreciate any help!

[Timothy B.]

Re: '63 heater airflow problem

Erik,

I bet you have the first design 63 heater box, I will try to get a picture of mine later today. Check the archives for more info from years back as I seem to recall discussion.

If you push the dash cable in and pull to the detent for floor air are you saying you get no air? Mine works OK but after pulling for defrost and pushing back in to floor position some air still comes through the defrost. If you go all the way in then back out to the floor position air flow is better. PIA but you can get it to work ok...

[Wayne W.]

Re: '63 heater airflow problem

I worked on one a while back that was doing about the same. They are rather primitive. What I found was that there was a spring missing. It goes on the slider mechanism down to a clip. That spring and some adjustments made it work.

[Harry S.]

Re: '63 heater airflow problem

The first picture is a late 63 to 67 box. The second picture is one of the versions of the early 63 box. The early 63 Micky Mouse setup needs constant adjustment. Also both boxes are prone to internal flapper rust and seal failure.

The external adjusting should take care of what your looking for.

[Timothy B.]

Re: '63 heater airflow problem

Great pics, Harry.

I had to make a new spring for mine as that was long gone and it made the assembly work better. I need to check if I reinstalled the flat washer behind the slots in the control.

A true 63 nightmare and for me it was difficult to find info on the early control. Now that we have the internet it's much easier.

[Harry S.]

Re: '63 heater airflow problem

Also for 63, depending on an early box or a late box, the Y duct is different for each.

[Bill C.]

Re: '63 heater airflow problem

Erik
Sorry to hear of your problem. I went through the same problem(missing spring). However, I remembered to check my owners manuel. I says to pull the air-def control to the detent position BEFORE turning the blower on. Maybe this will help.
Regards
Bill

[Erik H.]

Re: '63 heater airflow problem

Thanks for all of the replies. I definitely have the early style unit, that looks like the photo Harry posted on the right. It's also got the notched outlet on the drivers side. When pulling out to DEF, I get a nice bit of tension and can clearly hear the mechanical activity of the door opening and then closing when I push back in. With the pull all the way in, and then pulled out to the first detent, I get zero tension and hear no mechanical activity. Ideally, I'd like to fix this in the car if possible. What I don't yet understand is how the unit works. Is there a single door inside for the DEF and heat mode, or two separate doors? What's the best way to approach it (eg remove the driver's side heater/radio panel to get access?)?

[Harry S.]

Re: '63 heater airflow problem

Hope this helps. I've also included the two Y ducts and the two snouts.

This is my early box before I restored it. There is a third flapper that closes off the heater core from these two flaps. That flap is controlled by it's own cable.

On the other cable when the flap on the right is down and the one one the left is up and the air goes to the windshield. When they are both up the air goes to the side radio vents.

[Erik H.]

Re: '63 heater airflow problem

I feel like I'm trying to solve for one of those geometric math problems in school - needless to say, I wasn't very good in math! Here's what's happening:
My heater box looks exactly like Harry's, and my slide bar/spring is in the same mounted position as his. I've copied his photo and added the words Left and Right to the flaps. My box is working like this:
Heater pull closed: Left DOWN, Right UP
Heater pull on heat: Left DOWN, Right DOWN
Heater pull on Defrost: Left UP, Right DOWN

I now understand why I have no heat blowing through the vents. What I don't understand is what's wrong with the configuration. The flaps seem to be just that - flaps without the ability to adjust them. The only two adjustments I can see is the metal arm on the side of each flap that slides against the inside of the box and the spring on the sliding arm. Any help on where to start? Driving me crazy! Thanks!!

[Harry S.]

Re: '63 heater airflow problem

Erik, I just took another early box I restored off the shelf and ran it through a cycle.

When in the defroster position the right flap does not completely shut off the air to the radio side vents, there is about 3/4 inch gap between the flap seal and the fiberglass. The left flap is open but not all the way, about 80 percent.

When in the other position (air to the radio side vents), the right flap does not completely close the opening to the defrost opening. Both left and right flap are open.

What I described could be because of age, how it worked in 1963 is just a guess. I did have to add white lithium grease to get it to operate smoothly.

[Bill C.]

Re: '63 heater airflow problem

Harry
Great photos; thanks. Are you able to identify the different applications for the two snouts you show?? Are they both 63's; early or late?
Regards
Bill

[Harry S.]

Re: '63 heater airflow problem

Harry
Great photos; thanks. Are you able to identify the different applications for the two snouts you show?? Are they both 63's; early or late?
Regards
Bill

Bill, as far as I know that part was only used in 63. I'm still trying to figure out why there is a difference. Many 63's I've seen no longer have the part installed, it's been long lost. Therefore, with few 63's available to look at comparison is difficult as most folks do not want to take the side panel off.

[Bill C.]

Re: '63 heater airflow problem

Thanks Harry. I am looking at the AIM. I dont see this part in the heater section. It only shows up in the A/C section. Did this only appear on the latter heater boxes??
Bill

[Jack H.]

Re: '63 heater airflow problem

"What I don't yet understand is how the unit works."

Shouldn't be any mystery here... There's a general schematic of the system proudly published as Fig. 2 of Section 13 in your copy of the 1963 Corvette Shop Manual.