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waywardson1963
Novice
Aug 12, 2010, 1:39 PM
Post #1 of 17
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hello,I've got a 94 towncar and the air works fine when Idle or not going uphill or passing other vehicles etc... but when and if I pass a car or go uphill it starts blowing warm air ! any and all suggestions would be appreciated ,God bless...
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Hammer Time
Ultimate Carjunky
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Aug 12, 2010, 1:44 PM
Post #2 of 17
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There are a couple things that could be going on here......
First, it has a wide open throttle cutout relay. If the TPS is reading wring, the PCM will sense wide open when it isn't and shut off the relay. It also has a high engine temp shut down and if it's getting marginally hot, the PCM may be shutting it down.
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waywardson1963
Novice
Aug 16, 2010, 12:38 AM
Post #3 of 17
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TPS,PCM? could there be a possibility of low freon? ty
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Tom Greenleaf
Ultimate Carjunky
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Aug 16, 2010, 12:48 AM
Post #4 of 17
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Re: 94 Town Car A/C
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Wicked common with these is low tech. Check clutch gap. More that .020 is too much. They quit pulling in at about .030+.
Take a shim out but don't allow rubbing. Heat = lack of magnatism so stupid clutch can't pull in. Keep the 8mm wrench in my pocket these are so common. 5 Minute repair,
T
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Tom Greenleaf
Ultimate Carjunky
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Aug 16, 2010, 5:46 AM
Post #6 of 17
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Re: 94 Town Car A/C
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It's Sooooo common as said I carry the wrench. Profile doesn't fit exactly 'cept magenetic pull force is heat dependant and it's still not a perfect match for the issue,
T
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Hammer Time
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Aug 16, 2010, 5:56 AM
Post #7 of 17
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Re: 94 Town Car A/C
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I've usually found a weak clutch to act just the opposite from this. The higher RPM raises the voltage and triggers it to engage and they fall out at idle.
Make it's not just the air flow that's changing to defrost that your seeing. That would be a simple vacuum leak.
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Tom Greenleaf
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Aug 16, 2010, 8:44 AM
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Re: 94 Town Car A/C
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This is too commom! Weak clutch coil would show out of range 3.5 to 4.5 ohms and never found one yet.
Tom
(This post was edited by Tom Greenleaf on Aug 16, 2010, 8:46 AM)
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waywardson1963
Novice
Aug 19, 2010, 10:55 AM
Post #9 of 17
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Re: 94 Town Car A/C
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Tom,originally I said in a strain it started blowing hot air but instead hardly any air comes out hot or cold. would it be the same diagnosis still? tyvm
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Tom Greenleaf
Ultimate Carjunky
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Aug 19, 2010, 11:30 AM
Post #10 of 17
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Re: 94 Town Car A/C
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?? Are you saying air flow isn't coming out the desired vents like panel, defrost, on your feet or not blowing at all?
T
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waywardson1963
Novice
Aug 20, 2010, 8:25 AM
Post #11 of 17
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Re: 94 Town Car A/C
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ok,while idle or not in a strain such as passing or going up hill it will blow good cold air but if passing or going up hill the airflow out of the vents just about completely shuts down in other words then no air hot or cold! but after you level out it starts blowing cold air again ty for all your help
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Tom Greenleaf
Ultimate Carjunky
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Aug 20, 2010, 8:54 AM
Post #12 of 17
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Re: 94 Town Car A/C
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?? OK: This changes the approach. What I'm understanding is that the blower quits under load! That's a first for me and I can't think of a device to shut down the blower motor with load. HT already mentioned some vehicles will shut down compressor under heavy loads but I don't think most of these had that feature.
Load is about always measured by intake manifold vacuum. Higher Hgs mean less load. At WOT (wide open throttle) a guage would read zero or close.
Unless someone mis wired a cut out for loads I can't think of a common denominator. A TPS (throttle position sensor) is part of guessing at the load and what to adjust.
I think right now I'd hook up a test light to the blower itself to inside where you can see it and see if it loses power during this situation. Blower also needs ground which may be load sensitive with just the extra torque on engine a ground wire/strap for blower may lose connection as the engine does move some with load. Actually I think that's more likely with this.
You could add a known ground to known body ground directly to the ground for the motor as a test.
As said - this is a first. Guess is loss of ground but can't understand why that's so predictable. You would think that would be intermittent.
Look for ground straps they put everywhere. Engine to body, body to frame/chassis which are usually just braided bare straps but they are there for a reason.
This changes the whole direction of figuring this out to me as said.
A/C relay for this should be well marked underhood. They are only about $bucks even at a Ford dealer! I'd just toss it for new to rule that out and if no change you have a spare that will fit other items in that same relay/fuse center,
T
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Hammer Time
Ultimate Carjunky
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Aug 20, 2010, 9:58 AM
Post #13 of 17
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Re: 94 Town Car A/C
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OK, things are becoming clearer now. I don't believe your A/C is shutting off. The blower is simply switching to defrost.
The mode selection is done through a series of air doors that are operated by vacuum. When there is either a partial or total loss of vacuum, the system will default to either defrost or on some vehicles, heat. Acceleration can also have an effect on the doors for the same reason.
Look under the hood for a small black plastic hose coming through the firewall. Follow it to the vacuum source looking for any breaks, cracks or leaks. Also follow any other lines that branch off because they may go to a vacuum reservoir (storage tank) and a leak there will cause the same problem. Using a vacuum gauge to determine if you have full vacuum at any given point is the best way to find it. You can cut into the line anywhere and splice it back together with a piece of vacuum hose. Find the broken line, you found your problem.
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waywardson1963
Novice
Aug 20, 2010, 7:41 PM
Post #14 of 17
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Re: 94 Town Car A/C
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you are right ,I just checked it and the air is switching to defrost! If I can't find the leak is there a manuel way I can open the door and keep it open? ty so very much for your help because I'm on alot of meds that I dont need to be in the extreme heat with adn financially I dont have the resourse to fix the car so again thanks much.
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Hammer Time
Ultimate Carjunky
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Aug 20, 2010, 7:44 PM
Post #15 of 17
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Re: 94 Town Car A/C
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It would be easier to find the leak and repair it.
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Sidom
Veteran
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Aug 20, 2010, 8:30 PM
Post #16 of 17
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Re: 94 Town Car A/C
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One suggestion I'll add is about the vacuum storage reservoir... Some cars have them and pretty much all Fords do but make sure you car does have one. It should look like a black plastic ball with 2 vacuum lines... If for some reason there isn't one....get one and it should help your problem....
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waywardson1963
Novice
Aug 21, 2010, 10:08 AM
Post #17 of 17
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Re: 94 Town Car A/C
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thx hammer!
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