AC cutting out under hard acceleration seems to be a common problem for Econolines. However mine doesn’t seem to exhibit the same problem as others have reported. Some claim that under such acceleration their AC switches from the dash vents to the defroster vents. I don’t know if for them cool air comes from the defrosters or just blowing air. Regardless, the fix is bypassing the factory vacuum canister and the associated check valve. Vacuum lines are rerouted and replacement parts are mounted under the passenger side dash.

Before I attempted the bypass “fix”, I noticed that under acceleration, my blower motor shuts off completely, no air — cold or otherwise blows. After the bypass I noticed no difference in the results.

I have installed a vacuum gauge in my van that I constantly monitor. Under normal driving my vacuum is good and my AC works great. What is the likelihood of me having a vacuum leak?

As a side note, through the years I have heard of vehicles having an AC compressor cutoff switch that is activated under hard acceleration. Does Ford do this? If so, I would expect my blower to continue to blow. What am I missing or doing wrong?

 

Ok, I was somewhat wrong. My AC does blow from my defrost vents under hard acceleration. I had my blower on low and it was harder to notice. On high, it was obvious but I am not sure if it was cold.

As I said on my previous post, I made the popular bypass fix and expected AC air to blow from my dash vents. From which set of vents does air blow on a properly working system of a 2002 E-150 and does it blow cold?

 

In fail-safe mode it defaults to defrost vents so you need to identify the problem.



I randomly picked V8-4.6L since you didn't read my signature. Anyway, you need to find out why your vacuum reservoir is not doing its job, you might have a leak on the tank itself or its vacuum connection.

 

Make sure you replace the check valve when you do the vacuum canister relocation. I did the fix 8 years ago in my 2006, but have replaced the inline check valve twice since then.