Thermostatic Air Control Diaphragm, defective?

[visionguru]

With the air cleaner cover off, the air temperature should be considered cold (70F outside, and the car is cool). Is the hot air door supposed to be open?

This seems to be CLOSED. When I pinch the vacuum hose connects to the diaphragm, the pin seems to move a little bit, but not enough to get the door open.

Is this thing defective? What are the procedures to determine?

As far as I can understand, when cold, this door should be open to let the hot air in. Is that correct?

Thanks for any hints.

[A20A1]

Something isn't holding vacuum or you have low vacuum to begin with.

Check the "AIR BLEEDS VALVES" as well as the check valve under the air filter box.

[lostforawhile]

ok my camera isn't working yet because of my computer crash,but i'll try to explain. there is a vaccume line that comes off of the metal tubing on the engine,this is your vaccume source it goes to a check valve and the the air door,there is also a bleed valve that is installed inside of the air filter area,this is the funny looking little metal flat thing with a teed off vaccume line that connects to the same line as the air door motor(the little vaccume thing) what this does is when the air reaches a certain temp it opens and bleeds off vaccume to the air door motor causing it to close and shut off the hot air coming in. it's possible that this is bad and causing air to bleed all the time, the way to check it is to apply a vaccume source to the vaccume inlet line with the hose to the bleed valve blocked off. if the door rises with that blocked off it's the culprit,now don't bypass this or you'll get hot air rising into the air cleaner all the time. this is your thermostat for the system in other words. if you pull off the air cleaner and disconnect the bottom hot air hose,you should be able put your finger up there and push the air door open. if it doesn't move time for wd40. if it moves and you suspect it's the air door motor, you need to apply a vaccume source to it's fitting and see if the door rises, 99 percent of the time it's this or a cracked hose. every air door motor i've found so far has been bad. to remove it just twist to unlock it and carefully slip the pin out of the little hook on the air dor. installation is the reverse. no tools needed.

[visionguru]

lostforawhile, A20A1, thanks for the information. Now I understand this a lot better.

I plan to use a vacuum pump to pin point the problem.

Thanks! You guys are super.

[visionguru]

I run a test using a vacuum pump. The Air Control diaphragm does not see to hold vacuum as it's supposed to. It did move a little bit, but once it moves, the vacuum dropped to 0. Anyway to repair this thing? Or do I have to buy a new one (which is very hard to find)?

By the way, the vacuum hose connects to this thing is very hard to remove, any good tips on how to remove vacuum lines if I need to remove more for diagnosis in the future?

[Cant Stop]

vacuum hose you should buy some to replace any rotted or stiff hoses you may have.