I need help. My a/c stops blowing from the vents when I accelerate. It continues to blow through defrost vents and from rear of center console. If I let off the pedal...it starts blowing again from dash. Any Clues? Please e-mail me at firemedic00@***.net if you have a fix....

Thanks!!!!

 

I have the EXACT same problem on my 4.6L V8 99 F-150 XLT. Anyone know what the problem is? I'm thinking it's something with a vacuum hose, but I could be wrong... Email me with answers please, it's HOT!!!! Gibb3r@msn.com

 

If your air is going to the defrost, you are losing vaccuum to your controls. Defrost is the default outlet when there is no vaccuum.

My problem is: After a few hours driving with AC, NO air comes out. The blower is still blowing, what air that is coming out of the vents is still cold, but it's just not coming out!! just like it's plugged up somewhere. Is there a cabin air filter that could be freezing up or something?? After 20-30 minutes after I shut truck off, it blows fine again

 

firemedic and gibb3r:

Your question was address about a week ago in a thread that will be obvious if you just scroll down the page. Exact same issue.

CharlieHo:

When the airflow does diminish, does it feel clammy or moist as it goes away? If so, your evaporator is icing. To double check, drive it until the A/C quits cooling, then park it. Observe how much, if any, liquid drains out the condensate drain tube. If there is a significant amount,ie, a large puddle, that indicates that the chunk of ice is melting. Evaporator freezeup is often due to improper charge level in the system.

Any cabin air filter, if present, would affect any airflow position that draws in outside air only. The MAX A/C does not flow air through any filter. This is a good bit of information to help locate the reason for your airflow restriction.

Steve

 

ProjectSHO thanks for the reply. I lose air even in max a/c position so I guess it's not a filter issue. I usually don't notice it's no longer blowing a lot of air until I start getting hot. I hold my hand in front of the vent and what air is coming out is cold, just not very much. It has only quit blowing on me three times, all 100 mile trips, and I notice it roughly 75-80 miles along...

I will vac the system and recharge and see if that helps. Again, thanks for thje reply.

CC

 

I am having the same problem!! Did you find out how to fix this? I would appreciate the help

Thanks~
gone_racin@hotmail.com

 

Same exact problem with my 98 150. Checked my vacuum hoses and all appers OK, don't know what else to do. Could it be electrical related?

 

In case you can't figure out how to scroll down a month ago...

https://www.f150online.com/forums/sh...d.php?t=206938

Need help holding that spoon????

Steve

 

Hey SHO, how tough is it to be perfect?

 

This is the fix for when thA/C blows through defrost the whole time, but my problem is different..

HELP!!!!!!! pLease.....

When driving my 94 F150, my A/C stops blowing when near or above 2k rpm. I checked all the vaccum in the engine bay and all the vaccum lines under the dash. All are connected and working fine.

Today a new problem came about. While driving at or above 2k rpm, the a/c stops blowing (never turns off) and the engine starts "coughing" but never shuts off either. If I turn the air off right away the engine levels out and the "coughing" stops.

(If I take my foot off the gas pedal, the A/C starts blowing again.)

When i bought the truck I was told the compressor had a SMALL leak, so i filled it with freon and checked for leaks with a leak detector but was unable to find any leak. Here I am a week after putting in freon and the A/C is still cold (not as cold as a week ago so I do believe there is a small leak).

My questions are:

Can low freon levels cause the air to stop blowing at 2k rpm and above?
Can low freon levels make the car "cough"?

also, i mean air stops coming out of the vents but you can hear the blower and AC still going...

Also checked the flapper that redirects air from the vents to the dash defrost and the flapper works fine. You hear the air keeps blowing into the dash somewhere but never comes out of any vent or defrost

 

No and unlikely.

You still have a problem with marginal vacuum supply, probably due to a leak that you haven't found yet or perhaps a check valve that is not working properly.

When the throttle plate is opened, manifold vacuum drops. When you release the throttle, the vacuum rises again.

The misfire is probably due to the secondary ignition system. When the misfire occurs, your vacuum drops or varies.

Steve

 

so finding and fixing the vacuum leak will cure the misfire as well?

 

Only if the misfire is due to a vacuum leak. Typically, misfires are due to plug or wire issues.

Steve

 

what would explain the misfire only when the A/C is on?

 

Check the little plastic "manifold" located between the battery and the firewall. My '97 Expy was showing the same symptoms (loss of A/C when under accel). I actually heard the leak before I found it. One of the legs of the manifold had broken. The plastic had become brittle.

Good luck!