A/C Problem

[FINCH239]

I really don't know a thing about Air Conditioning in my car. When I turn on the A/C it only blows air through the Defrost Vent and the Floor, but doesnt blow air through the front vents. If anyone knows how to fix this problem or has a hint to what i can do to fix this, it'll be much appreciated. It's just starting to get hot and humid here in florida and i need the A/C. Thanks!

[way2old]

Somewhere in the system you have a vacuum leak. You need to trace it line by line until you find it. Start at the vacuum cannister and work toward the controls.

[FINCH239]

where is the vacuum canister located?

[way2old]

Year please.

[FINCH239]

its a 2003

[way2old]

The reservoir is the square black plastic box on the drivers side inner fender. It has a small relay box attached to it. Follow hoses to engine and the other one goes to the controls inside the car. Takes a while to trace them all through.
Here is a diagram.

]

[sleepy hollow]

I have the same problem on my 2003 Grand Marquis.

I am getting vaccuum at the black input to the control module. The defrost and floor vacuum motors work fine. When I move one of the vacuum lines from a working vacuum motor to the dash vent motor, I get air from the dash vents when in defroster/floor mode. That means to me that the dash vent motor is fine. So, that is how I am operating now. It works just fine, but the fan has to be controlled manually, of course.

My guess at this point is that it is somewhere in the control module. The self test shows no codes. So, perhaps the electronics are fine.

If so, then the problem might be the vacuum acutator for the blue line. I dissasembled the control box, and removed the vacuum acuator assembly, but decided not to do anything further as I ran out of time and needed to get the car in service for the week. I put it all back together and installed as indicated above. Can this component be replaced or repaired? How can I tell if a single actuator is on the fritz?

Or, is there some other possible cause?

Thanks.

[HEMIDAZE]

My 98 had the same problem when in warranty. The dealer found a vacuum hose burned through because it ran too close to the manifold. They never showed me where.

[sleepy hollow]

Thanks for your response. Since I am getting vacuum at the control module, I don't think there is any problem with the vacuum source in the engine compartment.

I wish it were that simple. As far as I can tell there are no issues with the vacuum hoses or connections. So, that tends to lead me to the control module. That will hurt if I have to buy a whole new module. I'll live with a manual approach to cooling until I figure out a cheap way to fix this. Not a big deal really.

[Doccpops]

I have a 2003 and just started having the same probelm, It will randomly change from floor to defrost to vent and then finally settle in to vent if i have it set to automatic. I was about to take it to a dealership until I read this forum. I think I will try to find the leak myself!

BTW, How hard is it to change the plugs on the 2003 4.6? I had change my plugs, but when I got my merc back, it ran no better, and there were no finger prints on the coil overs, like they had never been touched. The dust was not disturbed at all. I want to check and change the plugs if needed and take my old plugs (if they wern't changed) back to ford and let them know how I feel about the whole thing!

Greg

[edmaude]

Guys

Sorry to post on an old topic, but my 2006 just started to operate on only defrost/floor. last week it did this once, but when I turned car back on it worked fine a few times on all settings and now nothing but defrost/floor. Since it is winter and I use those 2 settings most it is not the end of the world.

This is the 2nd EATC problem and I am pissed since the car is not that old. When under warranty the speed controler was replaced due to it not turning off and only blasting at full force.

Tried to find the vac canister today as per the diagrams and was unable to locate. Any insight would be a big help before I spend more money.

[sleepy hollow]

In case edmaude has not fixed his problem or if anyone else is interested in this topic, here is another thread that may be of interest, including how I fanally fixed the same problem on my 2003 GM.

http://www.automotiveforums.com/vbul....php?p=5950515

[pcmos]

Please post all the details regarding your Grand Marquis (year, model trim, climate control system). I solved a very similar problem on my 2003 LS Ultimate with the digital automatic climate control. The flow of air is controlled by a vacuum actuated door buried in the dash. There are two different climate control systems on the marquis. One system uses a digital control head, the other is a more traditional system with manual dial controls.

Both systems use vacuum controlled actuator doors for air flow. The digital system works by incorporating small electronic solenoid valves to change the vacuum distribution based on your command inputs. The digital system obviously needs to convert your digital inputs to mechanical vacuum actuation. Ford designers accomplish that task with the vacuum solenoids inside the digital control unit itself. (In contrast, my Buick LeSabre uses electric motors to control the airflow door, so they don't have any vacuum actuation.) When you remove the digital control unit from the dash there is a large vacuum manifold port on the back with something like 6 different line connectors grouped together. You can go to harbor freight tools and purchase a hand vacuum pump for next to nothing.

I basically diagnosed the system by connecting the hand pump to the various ports on the connector and actuating the blend and vent doors manually. Obviously when you perform that test you will want to keep the climate control electrical connectors hooked up as usual, with the unit sitting outside the dash. The only thing you should have unplugged is the vacuum port. I'll have to dig through my shop manual to find the vacuum diagram again. Essentially you can use the hand pump to verify that the door isn't stuck or faulty. You should be able to change the airflow with the hand pump alone. You just pull the hand pump trigger a few times and the airflow will switch from defrost/floor to center just like it is supposed to do.

If you can make the actuator function with a vacuum hand pump and you also feel vacuum at the connector with the engine running, then chances are you need a new control unit.

I took it a step further by actually diagnosing the digital control unit at the component level, which is obviously not any sort of recommended service procedure. The problem turned out to be the tiny o-ring seals inside the vacuum control solenoids. I was able to rebuild my digital climate unit by repairing the vacuum solenoids with new HNBR o-rings. It's now been working fine for more than a year. Your best bet is to get a replacement digital control unit on ebay or from a junk yard. Unless you normally feel comfortable doing some pretty serious DIY repairs I wouldn't recommend that you try and mess with the guts of the digital climate module.

Diagnostic procedures for the manual control system would be very similar but I'm going to go out on a limb and guess you have digital climate control.

[sleepy hollow]

If you need a new EATC module, I highly recommend these guys www.autoecu.com.

They rebuilt my unit and offer a lifetime warranty for $180, which includes return shipping.

This is a better solution than a used module since the problem appears to be chronic with this module. If you buy one from a junkyard, you may have the problem again if/when that unit fails. Besides, prices for used units were not much less than 180, and sometimes more.

Just my 2 cents.

[kimokeo]

edmaude

Did you get your ac fixed? MY 2005 started shifting from vents to defrost when I accelerate and is to the point now where it almost stays defrost. On my model the black box is not on the drivers fenderwell. Anyone have any ideas?
Thanks
Kimo