A/C issue

[RF Overlord]

I will check for vacuum leaks.... or does Napa not sell the correct O-rings?

Dom the correct size is -007.

If you had no vacuum at all, it would never work on the vents, it would be stuck on defrost all the time. It sounds like you have an issue with the vacuum reservoir, which is there specifically for this issue. It's the square black box on top of the driver's fender liner. There should be a vacuum hose running from there to behind the driver's cam cover, where you should find a tee and a white check valve. One side of the check valve goes to the vacuum supply from the manifold, the other side goes to one leg of the tee. The other two legs of the tee go to the reservoir and to the EATC.

[burt ragio]

Often thought what purpose the black box had located on the drivers side inner fender. Great explanation.

[O's Fan Rich]

I put in Napa rings and nothing really changed.

Upon starting the car, air came out the vents, but it was warm and I could not adjust where the air flow was coming from.

I decided to drive the car.... like I do and things went back to the way they started.

Cold air out the vents until half throttle or greater, then air goes out the defrost and will not come out the vents until I turn everything off and on again.

I will check for vacuum leaks.... or does Napa not sell the correct O-rings?

Thanks so far guys.

That's how mine acted until it finally went full defrost ( must be the failsafe mode). The EATC ring replacement was the cure.

[Motorhead350]

I had o rings go out before and the issue was not quite the same.

I will check out the lines by the box in the firewall. I already replaced it before but a bad or pinched line sounds like the issue.

Thanks everyone.

[vegasmarauder]

Make sure the vacuum check valve (on the firewall connection) is still a check vavle. Air should only go towards the engine, not back in the car when you blow through it. Had one go out on a Lincoln and it would do the switch to defrost/floor when slowly adding more throttle while climbing a hill. Close the throttle and 10 seconds later the vacuum built up enough to work correctly. Thats the purpose of the check valce and vacuum supply tank to even out the vacuum in low vacuum engine situations. Been that way on Fords since the early 50's vacuum wipers.

[Motorhead350]

Where is this check valve?

I thought I found the leak, but I was wrong.

[RF Overlord]

Right where I said it is.

Behind the driver's cam cover.

[Motorhead350]

I have getting ZERO vacuum to the EATC, so the O-rings are out of the picture.

I checked that vacuum line by the drivers head and it had zero air flow.

Does anyone have a chart for this setup?

It's a leak, but I need to find out were to look and trace it back.

Thank you all. You have been great.

[fastblackmerc]

It's a simple schematic.

Engine vacuum to check valve to vacuum reservoir tank to EATC connector (black hose).

You need to trace the hoses.

[Motorhead350]

Thanks Jim.

I'll be busy with this tomorrow.

[Fastbob]

http://www.justanswer.com/mercury/56...low-vents.html

Try this for a diagram of the vacuum system on these cars.

[Motorhead350]

Thanks man!

About to throw in the towel.