so when i bought the 93 f150 each vent selector worked. defrost mix max ect.....well today i turned the ac on and it will only blow on defrost..... heat and ac still work fine so the little arm under the dash that mechanically pulls on the vacuum operated thing , well i unhooked it and manually move it and itll go from defrost and vent fine like that also on ac setting it recognizes the need to run compressor and does so . so the switch at the dash is telling the computer to actuate the ac compressor. but it wont switch vent settings. on the mix setting i can hear a clicking noise . i think its coming from the firewall area. can anyone make sense of this?
weird hvac issue
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no computer stuff on that ac system. all vacuum or cables. look near the passenger side hood hinge for a broken plastic vacuum line that comes out of a loom and goes to a valve also near that hinge. if that's not it there is a bunch of vacuum hoses on top of the intake manifold. ck those closely
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not sure if this will help chevyboy had a dodge car do that the clicking noise it was a blend door actuator .
You have a vacuum problem. First verify you have vac to the main line to the AC control head, usually a black line. Also verify no one knocked off the connector to the fresh/recirc actuator under the dash in the pass footwell (not specific to your model but a lot of Fords in general).
Any lack of vac automatically defaults to defrost air output.
Any lack of vac automatically defaults to defrost air output.
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Originally Posted By: punisher
...Any lack of vac automatically defaults to defrost air output.
That's an interesting design philosophy. Of all the heating / air conditioning settings, the defroster is most critical to safe driving. Somebody was thinking when they set that up.
...Any lack of vac automatically defaults to defrost air output.
That's an interesting design philosophy. Of all the heating / air conditioning settings, the defroster is most critical to safe driving. Somebody was thinking when they set that up.
Originally Posted By: punisher
You have a vacuum problem. First verify you have vac to the main line to the AC control head, usually a black line. Also verify no one knocked off the connector to the fresh/recirc actuator under the dash in the pass footwell (not specific to your model but a lot of Fords in general).
Any lack of vac automatically defaults to defrost air output.
X2! A vacuum leak will default to defrost so that you at least have that.
Also check the vacuum reservoir under the hood and follow the vacuum lines coming from it. It is probably a black metal can or black plastic ball.
You have a vacuum problem. First verify you have vac to the main line to the AC control head, usually a black line. Also verify no one knocked off the connector to the fresh/recirc actuator under the dash in the pass footwell (not specific to your model but a lot of Fords in general).
Any lack of vac automatically defaults to defrost air output.
X2! A vacuum leak will default to defrost so that you at least have that.
Also check the vacuum reservoir under the hood and follow the vacuum lines coming from it. It is probably a black metal can or black plastic ball.
Right - vacuum leak is #1.
I hope it is an easy one!
I hope it is an easy one!
I didnt see anything under the hood. But i really dont understand the system and how it works.
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Originally Posted By: chevyboy14
I didnt see anything under the hood. But i really dont understand the system and how it works.
First step would be to put your ear to the HVAC control when you have it in the position that isn't working properly and listen to see if you can hear a vacuum leak.
I didnt see anything under the hood. But i really dont understand the system and how it works.
First step would be to put your ear to the HVAC control when you have it in the position that isn't working properly and listen to see if you can hear a vacuum leak.
None work except defrost and i didnt hear anything
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Originally Posted By: chevyboy14
None work except defrost and i didnt hear anything
Well if none of them work except defrost, the vacuum leak is, as others have mentioned, probably under the hood. Start listening around!
None work except defrost and i didnt hear anything
Well if none of them work except defrost, the vacuum leak is, as others have mentioned, probably under the hood. Start listening around!
Originally Posted By: chevyboy14
I didnt see anything under the hood. But i really dont understand the system and how it works.
Your HVAC controls operate off of engine vacuum. A vacuum can only occur in a sealed system. If there is a leak anywhere, you won't be able to hold a vacuum to operate the HVAC controls.
Look on the left side of the engine compartment behind the battery. There is probably a black soup can thing with a couple tubes coming off of it. If that or the tubes have a leak, you won't have HVAC controls.
I didnt see anything under the hood. But i really dont understand the system and how it works.
Your HVAC controls operate off of engine vacuum. A vacuum can only occur in a sealed system. If there is a leak anywhere, you won't be able to hold a vacuum to operate the HVAC controls.
Look on the left side of the engine compartment behind the battery. There is probably a black soup can thing with a couple tubes coming off of it. If that or the tubes have a leak, you won't have HVAC controls.
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Originally Posted By: 01rangerxl
Originally Posted By: chevyboy14
I didnt see anything under the hood. But i really dont understand the system and how it works.
Your HVAC controls operate off of engine vacuum. A vacuum can only occur in a sealed system. If there is a leak anywhere, you won't be able to hold a vacuum to operate the HVAC controls.
Look on the left side of the engine compartment behind the battery. There is probably a black soup can thing with a couple tubes coming off of it. If that or the tubes have a leak, you won't have HVAC controls.
Bingo
These systems are NOT complicated. They just have a lot of vacuum lines.
Originally Posted By: chevyboy14
I didnt see anything under the hood. But i really dont understand the system and how it works.
Your HVAC controls operate off of engine vacuum. A vacuum can only occur in a sealed system. If there is a leak anywhere, you won't be able to hold a vacuum to operate the HVAC controls.
Look on the left side of the engine compartment behind the battery. There is probably a black soup can thing with a couple tubes coming off of it. If that or the tubes have a leak, you won't have HVAC controls.
Bingo
These systems are NOT complicated. They just have a lot of vacuum lines.
I FOUND THE ISSUE!!!! the line that runs from intake and then hooks to that little connector and runs to the blower motor it had a hole in it.replaced it with a rubber hose and all is working cost me 97 cents
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Great to hear bud!
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