a/c cuts off

rsbronco · Aug 2, 2005

Well here it is guys. I have a 93 and just got the whole a/c system redone. I live in AZ so its nice to have. I have had my truck for 4 years and this is the first time it has worked. Trust me any a/c out here is better than none. The problem I am having is when I accelerate the fan stops blowing out of the vents. It's kinda annoying. I just recentely realized when it cuts out, it starts blowing out of the vents for the windshield (defrost vents). I have had this happen on one of my work trucks years ago. If anyone has had this or know of this problem let me know.

Thanks

Justshootme84 · Aug 2, 2005

rsbronco, the HVAC control has a vacuum line that selects vent or defrost. Look under the hood on the passenger-side for the blower motor on the firewall. Check the vacuum lines for a leak. that should solve your problem.

Seabronc · Aug 2, 2005

That is also why there is a vacuum reservoir. Usually you will fint a T shaped check valve between the main vacuum and the reservoir with one line going into the dash area. What your symptom is telling me is that the check valve is not functioning, is not installed, or there is a leak between the reservoir and the A/C.

It looks like the attached picture. The bottom connection goes to the main vacuum, one top connection goes to the reservoir and the other goes to the A/C controls.

Good luck,

>-

rsbronco · Aug 4, 2005

Thanks guys. Ill take a look at it this weekend.

misterzero · Aug 6, 2005

Well here it is guys. I have a 93 and just got the whole a/c system redone. I live in AZ so its nice to have. I have had my truck for 4 years and this is the first time it has worked. Trust me any a/c out here is better than none. The problem I am having is when I accelerate the fan stops blowing out of the vents. It's kinda annoying. I just recentely realized when it cuts out, it starts blowing out of the vents for the windshield (defrost vents). I have had this happen on one of my work trucks years ago. If anyone has had this or know of this problem let me know. Thanks

25660[/snapback]

you have a vacuum leak in the system that operate the panel door disconnect the black vacuum line that is in the engine compartment going into the passenger compartment and applied a hannd held vacuum pump such as a mityvac and apply vacuum if it hold vacuum that part of the system is ok trhe problem maybe in the engine compartment if you have any question you can email me a [email protected] i am a senior master technician for ford many years

B-Cack · Aug 6, 2005

I have a similar problem on the same vehicle... only mine works fine when it is in normal AC. When I kick it to MAX.... it works fine at idle, but upon acceleration it cuts out and starts doing the same thing? Think this might be the same problem? From my understanding, when in the MAX mode, you are taking air from the cockpit and recycling it through the sytem, thus keeping cool air flowing over the condenser. Is there another line that could have a leak in it from the cockpit back to the AC unit? Thanks, B-Cack

B-Cack · Aug 12, 2005

Anyone have any thoughts on this?

Seabronc · Aug 16, 2005

Anyone have any thoughts on this?

25985[/snapback]

See my post at the top of the page.

>-

deputydog2003 · Aug 22, 2005

I've got a 95 Bronco Full Size and mine does the same thing... (AC cuts out and blows through the defrost vents when accelerating. Can anyone guide me thorough the various points to check in the vacuum system for leaks (pictures would be very helpful.) I've already replaced the switch and the lines that come directly out of the switch (max/norm/vent/off/heat/defrost switch) because there was a small leak in the black tube. It didn't solve my problem though.

Also, my cruise control hasn't worked in years. I understand that may work off the vacuum system too? Any chance they can be related?

Thanks.

Seabronc · Aug 22, 2005

I've got a 95 Bronco Full Size and mine does the same thing... (AC cuts out and blows through the defrost vents when accelerating. Can anyone guide me thorough the various points to check in the vacuum system for leaks (pictures would be very helpful.) I've already replaced the switch and the lines that come directly out of the switch (max/norm/vent/off/heat/defrost switch) because there was a small leak in the black tube. It didn't solve my problem though.
Also, my cruise control hasn't worked in years. I understand that may work off the vacuum system too? Any chance they can be related?

Thanks.

26324[/snapback]

The purpose of the vacuum tank is to provide vacuum to the system durring conditions that cause low vacuum like you described. The vacuumn tank has a check valve connecting it with the vacuum system and the A?C system.

Follow the vacuum lines back to the check valve, most likely the check valve is bad or vacuum reserve tank is leaking.

See attached vacuum diagram, the source is direct from the main vacuum tree on the engine.

Ford used a vacuum operated servo motor in the Speed Control system up till 94, in 95 they had a better idea and went to an electrically operated servo. Diagram also attached.

We just had a post the other day about a potential fire hazard caused by one of the switches, ( the pressure switch on the masxter cylinder). See this post http://broncozone.com/forums/index.php?showtopic=5036

Good luck,

>-

deputydog2003 · Aug 23, 2005

The purpose of the vacuum tank is to provide vacuum to the system durring conditions that cause low vacuum like you described. The vacuumn tank has a check valve connecting it with the vacuum system and the A?C system.
Follow the vacuum lines back to the check valve, most likely the check valve is bad or vacuum reserve tank is leaking.

See attached vacuum diagram, the source is direct from the main vacuum tree on the engine.

Ford used a vacuum operated servo motor in the Speed Control system up till 94, in 95 they had a better idea and went to an electrically operated servo. Diagram also attached.

We just had a post the other day about a potential fire hazard caused by one of the switches, ( the pressure switch on the masxter cylinder). See this post http://broncozone.com/forums/index.php?showtopic=5036

Good luck,

>-

26330[/snapback]

deputydog2003 · Aug 23, 2005

Thanks for replying to my post question.

Would it be possible for you to send me a picture of the actual parts in the engine compartment. I think I know what I'm looking at, but I'm not quite sure.

Also, before I take it in to be serviced, can I replace the vacuum check valve and/or the vacuum tank to see if that solves my problem? Are these parts easily replaceable be me without special equipment, or do I need special equipment, or do I need to "drain" the vacuum system to do it?

Please let me know whether you recommend that I am able to replace these parts (with good mechanical aptitude, but no prior auto maint. experience or should I only let a qualified technician do it?

Thx.

Seabronc · Aug 23, 2005

Thanks for replying to my post question.
Would it be possible for you to send me a picture of the actual parts in the engine compartment. I think I know what I'm looking at, but I'm not quite sure.

Please let me know whether you recommend that I am able to replace these parts (with good mechanical aptitude, but no prior auto maint. experience or should I only let a qualified technician do it?

Thx.

26367[/snapback]

You should be able to replace the parts. Attached is a picture of the Check valve. One has vacuum lines attached and the other piece is a check valve alone. The vacuum line comming out the bottom of the disc attaches to the main vacuum tree. One of the others connects to the reserve tank and third one should go thru the fire wall to the A/C function selector. The reserve tank on your truck should be under the hood mounted above the wheel. First check for a crack or dammage to one of the vacuum lines. If they look OK replace the check valve first, all you have to do is pull the vacuum lines off the old one and put them on the new one. If it is a vacuum leak, I would expect it to be in a line or connection rather than the tank.

Good luck,

>-

a/c cuts off

rsbronco

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Justshootme84

Rest in Peace Friend! Never forgotten..

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