Max A/C shuts off
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Tuned
Joined: Mar 2004
Posts: 400
Likes: 2
From: South Texas
Max A/C shuts off
My 93 bronco blows cool air when it is on norm a/c. When I switch to max, I don't notice an increase in airflow and once the vehicle starts moving, it will quit blowing all together. After it shuts down it will suddenly start blowing again and continue this as long as it is on max. Normal ac runs fine. Any ideas?
Elder User
Joined: Mar 2003
Posts: 788
Likes: 1
From: Hendersonville, TN
I'd be interested to know this myself, as my 94 F150 just started doing the same thing. Idling, it blows Ok, but going down the road MAX shuts off airflow. I've noticed that when I back off the throttle and coast it will come back. I'm thinking vacuum leak, or bad vacuum resevoir, but I haven't had time to check it out.
Tuned
Joined: Feb 2003
Posts: 495
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From: Cincinnati, Ohio
Are you sure your evaporator isn't icing up? It may seem that it isn't blowing but the problem could be that the airflow is blocked by the iced up evaporator. By backing off the throttle the compressor slows down enough to allow the evaporator ice to melt some and the cycle to start over. In Normal mode air is drawn from outside which is warmer as opposed to Max which is recycling the inside air making it colder each time it cycles through the evaporator. You might try and check the evaporator lines as soon as this happens to see if they aren't frosted indicating the icing problem. Probably a low freon charge problem but to be sure should put a set of manifold gauges on it and check both high and low pressures against the service manual specs for the vehicle.
John
John
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Tuned
Joined: Mar 2004
Posts: 400
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From: South Texas
This dosen't explain why I don't feel the extra airflow when max ac is turned on initially but it could be, I will look into that possibility.Thanks for the advice.
Last edited by dino360; Aug 31, 2004 at 03:02 PM.
New User
Joined: Apr 2004
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Max AC shuts off
I had the exact same thing except my ac would redirect to defrosters. I found a broked white vacuum line close to the firewall in front of the passenge seat. (engine compartment) I just patched it with a 1" piece of clear tubing and it has worked perfect ever since.
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Tuned
Joined: Mar 2004
Posts: 400
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From: South Texas
I checked it out and it turned out to be exactly what BG03 said and in the exact spot. I found pinholes in the brittle vac hose and wrapped it in black tape. It seems to be working fine for now. Thanks guys.
