F.Y.I. A/C inop

[Curless]

Thought I should put this out there. Had the typical defrost only situation so I went after the control head, replaced all of the o-rings and....nothing, same result....should have checked the vac to the control head, there was none. The vac line had melted at the vac manifold under hood on the EGR tube. Could be in a better place to get to, holy crap is that a PITA!!!! Anyways, keep it simple and don't assume you have a bad control head!

[RF Overlord]

Thanks, Curless.

Most automotive HVAC systems are designed to default to the defrost position upon loss of vacuum. If your system works on vent but switches to defrost as you accelerate, like going up a hill, it's probably the o-ring issue. If, however, you're stuck on defrost only, then you most likely have a complete loss of vacuum.

[Kickingwing519]

I'm having the same issue, only cuts out going up hills or rapid aceliration, where is the o ring located, is that a dealer part, or would a local parts store have it. thank you in advance for your help

[Curless]

I'm having the same issue, only cuts out going up hills or rapid aceliration, where is the o ring located, is that a dealer part, or would a local parts store have it. thank you in advance for your help

Follow the instructions here:http://www.mercurymarauder.net/forums/showthread.php?t=36922

[RF Overlord]

...or here (http://www.mercurymarauder.net/forums/showthread.php?t=80673) with pix.

[Granddaddy Marq]

Are you close to Huntsville Al. If so I might be able to fix it for you.

[IwantmyMMnow!]

Are you close to Huntsville Al. If so I might be able to fix it for you.

He lives in Erin, TN...don't know how close that is to you...

[O3 pharoh]

so I went through the ringer with mine now. I had floor defrost with heat only, replaced the head unit with one case rebuilt and after a lot of work realized it was the blend door. after that repair I regained my temperature control. but i am still fighting the air blowing through defrost and floor. where is this vacuum line located so that I can check mine? thanks. any other thoughts or ideas, it would be hugely appreciated thanks again. need AC through vents in these 105 degree temps.

[Curless]

so I went through the ringer with mine now. I had floor defrost with heat only, replaced the head unit with one case rebuilt and after a lot of work realized it was the blend door. after that repair I regained my temperature control. but i am still fighting the air blowing through defrost and floor. where is this vacuum line located so that I can check mine? thanks. any other thoughts or ideas, it would be hugely appreciated thanks again. need AC through vents in these 105 degree temps.

Vac line that feeds the a/c is on the passenger side behind the throttle cables along the firewall. It runs over to the driver's side in the engine compartment and then thru the firewall. Inside the car it then runs back over to the passenger side right behind the control head and up into the vac harness on the passenger side. You can check to see if you have vac at the control head by pulling it vac lines off of the back of it. The black one is the feed or vac source. On the passenger side foot area right at the bottom of the dash you'll see the same vac lines as on the back of the control head. There is a connector there as well.

[Curless]

I just did all of this Saturday on my car, if you need to call me go right ahead. 616-988-1315 ask for Chris.

[O3 pharoh]

ok, sounds good. I have feed from the black line, not sure how strong it should be!? but there. checked connection on passengers side before posting up here and is good. only thing I wondered about was where the red and white hoses, I think, plug in there was air leaking somewhere in that area. but i can't get my fat hand far enough to feel where it is coming from.

[O3 pharoh]

Would the compressor have anything to do with how the air blows through the vents? Been wondering if it has been going out for a while now. And I have been wondering if it has been locking up lately. Thanks in advance

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[Curless]

The compressor has no affect on the vent operation.

[fastblackmerc]

The compressor has no affect on the vent operation.

Correct. Compressor only affects the cold air.

Could have an issue with the o-rings / EATC, vacuum line(s) or vacuum motor.

[Zim Hosein]

Correct. Compressor only affects the cold air.

Could have an issue with the o-rings / EATC, vacuum line(s) or vacuum motor.

Out of curiosity fastblackmerc, where is the vacuum motor located? :confused::o

[fastblackmerc]

Out of curiosity fastblackmerc, where is the vacuum motor located? :confused::o

All the vacuum motors are under the dash. There are more than one.

[Zim Hosein]

All the vacuum motors are under the dash. There are more than one.

Thanks fastblackmerc, much appreciated! :beer:

[O3 pharoh]

Vacuum motors? Great. Probably what is just out of reach. How can I check those for function? I have suction from black hose in back of eatc unit. Any write ups on that procedure if I need to replace? The o rings are good, eatc redone by case and double checked here, blend door replaced. So I guess those vacuum motors are up next! Those are the two silver cylinders behind eatc correct? Thanks.

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[fastblackmerc]

Vacuum motors? Great. Probably what is just out of reach. How can I check those for function? I have suction from black hose in back of eatc unit. Any write ups on that procedure if I need to replace? The o rings are good, eatc redone by case and double checked here, blend door replaced. So I guess those vacuum motors are up next! Those are the two silver cylinders behind eatc correct? Thanks.

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I believe that black line is the supply to the EATC.

The individual solenoids when activated by the EATC there is a supply of vacuum to the individual motors opening and closing their respective doors.

[O3 pharoh]

How can I test them or replace them? There happen to be any write ups on this? Thanks.

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[Mad1]

I'm closer to Erin, Tenn. (I'm in Nashville), and have all the parts to rehab an EATC.

I fixed mine a while ago.

email sent with contact info.

Mad1
Jeremy