Hi all! I'm running a 94 f350 7.3idi turbo 4x4 with an e4od. For those that don't know, I recently experienced hard shifting and clutching issues due to a bad PSOM and neutral safety switch. In the process I also replaced the VSS and did a rear diff service.

What I'm experiencing now is when the ac is off the truck runs and shifts beautifully, the best it ever has. As soon as the ac is on its shifting harder from 1st to 2nd and has noticeable hesitation. 2nd to 3rd showing hesitation also and all around it feels sluggish and inconsistent in power and shifting.

Has anyone experienced this or have any knowledge of what may be causing these issues?

 

I hope this helps...a quick look at the electrical diagram in my Haynes manual shows that regardless of year, the ECM or PCM receives a signal from the A/C system. Pin 10 on all F-series, and pin 10 and 43 on others. So maybe your control module isn't receiving the signal showing your a/c is on?

 

...or your compressor is about to seize and is putting a great amount of drag on your engine?

 

Thanks for the reply, I'll have to look into that when I have some time. It's quite frustrating. Does this mean there's possibly a short in wiring, a bad sensor or would it be the PCM/ECM?

 

If it were the compressor seizing wouldn't it be putting the same amount of drag wether its on or off? Or does something engage once turned on that would cause it? Also if that were the case wouldn't it have a hard time engaging and disengaging?

 

The compressor would only cause drag when the compressor clutch is engaged when you turn on the A/C. From what I've read, the IDI diesels don't have any electronic controls to speed up the engine when the A/C in turned on, they are strictly mechanical.

 

Did you ever resolve your problem? If so, what was the cause?

I have this issue as well, and turn off my overdrive until I'm cruising over 55mph. I'm also running 35" mud tires, which I'm sure makes the issue worse.